# White Mountains Insurance Group Ltd: Form 10-K for the period ended Dec 31, 2025

- Company: [White Mountains Insurance Group Ltd](/companies/wtm.md) (CIK 776867)
- Form: 10-K
- Filed: 2026-02-27
- Accepted by EDGAR: Feb 27, 2026, 09:21 ET
- Period: 2025-12-31
- Accession: 0001628280-26-012603
- Inline XBRL: yes
- Main document: https://www.sec.gov/Archives/edgar/data/776867/000162828026012603/wtm-20251231.htm
- All documents and exhibits: https://www.sec.gov/Archives/edgar/data/776867/000162828026012603/

## Figures reported in this filing

Standardized XBRL line items for the period ended 2025-12-31.

| Line item | Period | Value | XBRL concept |
| --- | --- | ---: | --- |
| Revenue | 12 months, 2025-01-01 to 2025-12-31 | $3.73bn | us-gaap:Revenues |
| Cost of revenue | 12 months, 2025-01-01 to 2025-12-31 | $151.8m | us-gaap:CostOfGoodsAndServicesSold |
| Interest expense | 12 months, 2025-01-01 to 2025-12-31 | $78.4m | us-gaap:InterestExpense |
| Income tax | 12 months, 2025-01-01 to 2025-12-31 | $126.9m | us-gaap:IncomeTaxExpenseBenefit |
| Net income | 12 months, 2025-01-01 to 2025-12-31 | $1.11bn | us-gaap:NetIncomeLoss |
| Diluted EPS | 12 months, 2025-01-01 to 2025-12-31 | $430.14 | us-gaap:EarningsPerShareDiluted |
| Basic EPS | 12 months, 2025-01-01 to 2025-12-31 | $430.14 | us-gaap:EarningsPerShareBasic |
| Diluted shares (weighted) | 12 months, 2025-01-01 to 2025-12-31 | 2,534,300 shares | us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding |
| Operating cash flow | 12 months, 2025-01-01 to 2025-12-31 | $550.5m | us-gaap:NetCashProvidedByUsedInOperatingActivities |
| Dividends paid | 12 months, 2025-01-01 to 2025-12-31 | $2.6m | us-gaap:PaymentsOfDividendsCommonStock |
| Share repurchases | 12 months, 2025-01-01 to 2025-12-31 | $202.6m | us-gaap:PaymentsForRepurchaseOfCommonStock |
| Total assets | at 2025-12-31 | $12.31bn | us-gaap:Assets |
| Total liabilities | at 2025-12-31 | $6.05bn | us-gaap:Liabilities |
| Long-term debt | at 2025-12-31 | $837.0m | us-gaap:LongTermDebt |
| Shareholders' equity | at 2025-12-31 | $5.43bn | us-gaap:StockholdersEquity |

## Business

As filed, 118,781 characters.

### GENERAL

White Mountains Insurance Group, Ltd. (the “Company” or the “Registrant”) is an exempted Bermuda limited liability company whose principal businesses are conducted through its subsidiaries and affiliates. Within this report, the term “White Mountains” is used to refer to one or more entities within the consolidated organization, as the context requires. The Company’s headquarters is located at 26 Reid Street, Hamilton, Bermuda HM 11, its principal executive office is located at 23 South Main Street, Suite 3B, Hanover, New Hampshire 03755-2053 and its registered office is located at Clarendon House, 2 Church Street, Hamilton, Bermuda HM 11. The Company’s website is located at *www.whitemountains.com*. The information contained on White Mountains’s website is not incorporated by reference into, and is not a part of, this report.

White Mountains is engaged in the business of making opportunistic and value-oriented acquisitions of businesses and assets in the insurance, financial services and related sectors, operating these businesses and assets through its subsidiaries and, if and when attractive exit valuations become available, disposing of these businesses and assets.

As of December 31, 2025, White Mountains conducted its business primarily in five areas: property and casualty insurance and reinsurance, municipal bond guarantee reinsurance, capital solutions for asset and wealth management firms, specialty insurance distribution and other operations. White Mountains’s property and casualty insurance and reinsurance business is conducted through its subsidiary Ark Insurance Holdings Limited and its subsidiaries (collectively, “Ark”) and Outrigger Re Ltd. Segregated Account 2023-1 (“WM Outrigger Re”) (collectively with Ark, “Ark/WM Outrigger”). White Mountains’s municipal bond guarantee reinsurance business is conducted through its subsidiary HG Global Ltd. and its reinsurance subsidiary HG Re Ltd. (“HG Re”) (collectively with HG Re, “HG Global”). White Mountains provides capital solutions for asset and wealth management firms through its subsidiary Kudu Investment Management, LLC and its subsidiaries (collectively, “Kudu”). White Mountains’s specialty insurance distribution business is conducted through its subsidiary WM Phoenix Parent, L.P. and its subsidiaries d/b/a Distinguished Programs (collectively, “Distinguished”). White Mountains’s other operations consist of the Company and its wholly-owned subsidiary, White Mountains Capital, LLC (“WM Capital”), its other intermediate holding companies, its wholly-owned investment management subsidiary, White Mountains Advisors LLC (“WM Advisors”), investment assets managed by WM Advisors, its interests in Bamboo Ide8 Insurance Services LLC (“Bamboo MGA”) and its subsidiaries (collectively, “Bamboo”) through a special purpose vehicle (the “Bamboo SPV”), MediaAlpha, Inc. (“MediaAlpha”), DavidShield PassportCard Ltd. and its subsidiaries (collectively, “PassportCard/DavidShield”), BroadStreet Partners, Inc. (“BroadStreet”) through a special purpose vehicle (the “BroadStreet SPV”), Elementum Holdings LP (“Elementum”), White Mountains Partners LLC (“WTM Partners”), Enterprise Electric, LLC d/b/a Enterprise Solutions (“Enterprise Solutions”), two special purpose collateralized reinsurance vehicles that provide reinsurance capacity to Bamboo (the “Bamboo CRVs”), certain other consolidated and unconsolidated entities (“Other Operating Businesses”) and certain other assets (collectively, “Other Operations”).

As of December 31, 2025, White Mountains’s reportable segments were Ark/WM Outrigger, HG Global, Kudu and Distinguished, with its remaining operating businesses, holding companies and other assets included in Other Operations. On December 5, 2025, White Mountains completed the sale of a controlling financial interest in Bamboo. As a result, White Mountains deconsolidated Bamboo on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations are presented within the Bamboo segment.

### ARK/WM OUTRIGGER

The Ark/WM Outrigger segment consists of Ark and WM Outrigger Re.

On January 1, 2021, White Mountains acquired a controlling ownership interest in Ark (the “Ark Transaction”). Ark is a specialty property and casualty insurance and reinsurance company that offers a wide range of niche insurance and reinsurance products, including property, specialty, marine & energy, casualty and accident & health.

During the fourth quarter of 2022, Ark sponsored the formation of Outrigger Re Ltd., a Bermuda company registered as a special purpose insurer and segregated accounts company, to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2023 underwriting year. Ark renewed its quota share reinsurance agreement with Outrigger Re Ltd. for the 2024, 2025 and 2026 underwriting years. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements. White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. WM Outrigger Re is not participating in the 2026 underwriting year; however, WM Outrigger Re remains exposed to losses that occur prior to the expiration of the 2025 underwriting year on June 30, 2026.

### Ark

Ark is a specialty property and casualty insurance and reinsurance company that offers a wide range of niche insurance and reinsurance products. Ark underwrites select coverages through its two major subsidiaries in the United Kingdom and Bermuda.

In the United Kingdom, Ark participates in the Lloyd’s of London (“Lloyd’s”) market through Ark Corporate Member Limited (“ACML”), Ark’s wholly-owned Lloyd’s corporate member, which in turn provides underwriting capacity to Lloyd’s Syndicates 4020 and 3902 and Additional Central Settlement Number (“ACSN”) 3832 (collectively, the “Syndicates”). ACSN 3832 writes business on behalf of Syndicate 4020. Ark Syndicate Management Limited (“ASML”), Ark’s wholly-owned Lloyd’s managing agent, oversees the underwriting of the Syndicates. The Syndicates underwrite a diversified portfolio of insurance and reinsurance product lines, including property, specialty, marine & energy, casualty and accident & health. Syndicate 4020 commenced underwriting on April 1, 2007, Syndicate 3902 on January 1, 2017 and ACSN 3832 on July 1, 2024.

In Bermuda, Ark underwrites through its wholly-owned subsidiary, Group Ark Insurance Limited (“GAIL”), a Class 4 Bermuda-domiciled insurance and reinsurance company. GAIL underwrites a diversified portfolio of insurance and reinsurance product lines, including property, marine & energy, specialty, casualty and accident & health lines. GAIL commenced underwriting third-party business in January 2021. In addition, GAIL provides capital to support ACML’s capital requirements at Lloyd’s (“Funds at Lloyd’s”). In November 2025, AM Best affirmed GAIL’s financial strength rating at “A/stable.”

In both jurisdictions, Ark underwrites business primarily through insurance and reinsurance brokers and wholesalers, both in the open market and through managing general agents (“MGAs”).

As of December 31, 2025 and 2024, White Mountains reported $6,146 million and $5,134 million of total assets and $1,594 million and $1,438 million of total equity related to Ark. As of December 31, 2025 and 2024, White Mountains owned 72.1% of Ark on a basic shares outstanding basis (61.9% after taking account of management’s equity incentives) and reported $465 million and $410 million of noncontrolling interests related to Ark. The remaining shares are owned by current and former employees of Ark. In the future, management rollover shareholders could earn additional shares in Ark if and to the extent that White Mountains achieves certain thresholds for its multiple of invested capital return. If fully earned, these shares would represent an additional 12.3% of the shares outstanding as of December 31, 2025.

### WM Outrigger Re

During the fourth quarter of 2022, Ark sponsored the formation of Outrigger Re Ltd., a Bermuda company registered as a special purpose insurer and segregated accounts company, to provide reinsurance capacity to Ark. Outrigger Re Ltd. was initially capitalized with $250 million of preference shares for business written in the 2023 underwriting year, of which White Mountains contributed $205 million. The remaining capital was provided by third-party investors. Outrigger Re Ltd. entered into collateralized quota share agreements with GAIL to provide reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2023 underwriting year. The proceeds from the issuance of the preference shares were deposited into collateral trust accounts to fund any potential obligations under the reinsurance agreements with GAIL. Outrigger Re Ltd.’s obligations under the reinsurance agreements with GAIL are subject to an aggregate limit equal to the assets in the collateral trusts at any point in time. The terms of the reinsurance agreements are renewable upon the mutual agreement of Ark and the applicable preference shareholder of Outrigger Re Ltd.

During the fourth quarter of 2023, Ark renewed Outrigger Re Ltd. for the 2024 underwriting year with $250 million of capital. White Mountains rolled over $130 million from its commitment to the 2023 underwriting year. The remaining capital was provided by third-party investors.

During the fourth quarter of 2024, Ark renewed Outrigger Re Ltd. for the 2025 underwriting year with $230 million of capital. White Mountains’s total commitment was $150 million, of which $130 million was rolled over from its commitment to the 2024 underwriting year. The remaining capital was provided by third-party investors. The reduced capacity at Outrigger Re Ltd. was replaced by Ark through traditional quota share reinsurance agreements. During the year ended December 31, 2024, White Mountains received net distributions of $123 million from WM Outrigger Re, which included a net return of capital related to changes in White Mountains’s capital commitments for the 2024 and 2025 underwriting years and reinsurance profits for the 2023 underwriting year. During the year ended December 31, 2024, WM Outrigger Re commuted its reinsurance agreement with GAIL for the 2023 underwriting year.

During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The reduced capacity at Outrigger Re Ltd. was replaced by Ark through traditional quota share reinsurance agreements. The capital was provided entirely by third-party investors excluding White Mountains. During the year ended December 31, 2025, White Mountains received net distributions of $10 million from WM Outrigger Re, related primarily to reinsurance profits for the 2024 underwriting year. In January 2026, White Mountains received a distribution of $128 million, which included a net return of capital related to its non-renewal for the 2026 underwriting year. White Mountains expects to receive additional distributions of reinsurance profits from the 2025 underwriting year in 2026.

As of December 31, 2025 and 2024, White Mountains reported $270 million and $236 million of total assets and $232 million and $196 million of total equity related to WM Outrigger Re. As of December 31, 2025 and 2024, White Mountains owned 100% of WM Outrigger Re’s preferred equity.

### Insurance and Reinsurance Overview

Generally, insurance companies underwrite insurance policies in exchange for premiums paid by their customers (the insureds). An insurance policy is a contract between the insurance company and the insured where the insurance company agrees to pay for losses suffered by the insured or a third-party claimant that are covered under the contract. Such contracts are often subject to subsequent legal interpretation by courts, legislative action and arbitration.

Reinsurance is an arrangement in which a reinsurance company (the reinsurer) agrees to indemnify an insurance company (the ceding company) for insurance risks underwritten by the ceding company. Reinsurance can benefit a ceding company in several ways, including reducing net exposure to individual risks, providing protection from large or catastrophic losses and assisting in maintaining required capital levels and financial or operating leverage ratios. Reinsurance can provide a ceding company with additional underwriting capacity by permitting it to accept larger risks and underwrite a greater number of risks without increasing its capital as much as would be the case without reinsurance. Reinsurers may also purchase reinsurance for themselves, which is known as retrocessional reinsurance, to cover risks assumed from ceding companies. Reinsurance companies often enter into retrocessional reinsurance agreements for many of the reasons that ceding companies enter into reinsurance agreements.

Reinsurance is generally written on a treaty or facultative basis. Treaty reinsurance is an agreement whereby the reinsurer assumes a specified portion or category of risk under all qualifying policies issued by the ceding company during the term of the agreement, usually one year. When underwriting treaty reinsurance business, the reinsurer does not evaluate each individual risk and generally accepts the original underwriting decisions made by the ceding company. Treaty reinsurance is typically written on either a proportional or excess of loss basis. A proportional reinsurance treaty is an arrangement whereby a reinsurer assumes a predetermined proportional share of the premiums and losses generated on specified business. An excess of loss reinsurance treaty is an arrangement whereby a reinsurer assumes losses that exceed a specific retention of loss by the ceding company. Facultative reinsurance, on the other hand, is underwritten on a risk-by-risk basis, which allows the reinsurer to determine individual pricing for each exposure.

Insurance and reinsurance companies incur a significant amount of their total expenses from policy obligations, which are commonly referred to as claims or losses. In settling claims, various loss adjustment expenses (“LAE”) are incurred such as insurance adjusters’ fees and litigation expenses. Loss and LAE are categorized by the year in which the policy is underwritten (the year of account or underwriting year) for purposes of Ark’s claims management and estimation of the ultimate loss and LAE reserves. For purposes of Ark’s reporting under GAAP, loss and LAE are categorized by the year in which the claim is incurred (the accident year). In the following calendar years, as Ark increases or decreases its estimate for the ultimate loss and LAE for claims in prior underwriting years, or prior accident years for reporting under GAAP, it will record favorable or unfavorable loss reserve development, which is recorded in the calendar year when such loss reserve development is determined. In addition, insurance companies incur policy acquisition expenses, such as commissions paid to agents and premium taxes, and other expenses related to the underwriting process, including employee compensation and benefits. A key measure of absolute and relative underwriting performance for an insurance company is the combined ratio. An insurance company’s combined ratio is calculated by adding the ratio of incurred loss and LAE to earned premiums (the loss ratio) and the ratio of policy acquisition and other underwriting expenses to earned premiums (the expense ratio). A combined ratio under 100% indicates that an insurance company is generating an underwriting profit, while a combined ratio over 100% indicates that an insurance company is generating an underwriting loss.

Ark derives substantially all of its revenues from earned premiums, investment income and net realized and unrealized investment gains (losses). Ark also receives fee revenues and profit commissions from business ceded to its reinsurers across multiple classes of business. Written premiums represent the amount charged to an insured or reinsured party to provide coverage under an insurance or reinsurance contract, which are recognized as earned premiums within revenue over the period that insurance coverage period is provided (i.e., ratably over the life of the policy or, in the case of catastrophe premiums, in proportion to the level of insurance protection provided.) Unearned premiums represent the portion of premiums written that are applicable to future insurance coverage provided by policies. A significant period often elapses between receipt of insurance premiums and payment of insurance claims. During this time, Ark invests the premiums, earns investment income and generates net realized and unrealized investment gains (losses).

### Lines of Business

Ark writes specialized lines of insurance and reinsurance across its United Kingdom and Bermuda platforms within five major lines of business: property, specialty, marine & energy, casualty and accident & health. Claims for property, specialty, marine & energy and accident & health coverages are typically reported and settled in a relatively short period of time. Casualty insurance (often referred to as liability insurance) generally covers the financial consequences of a legal liability of an individual or an organization resulting from negligent acts or omissions causing bodily injury, property damages and/or economic damages to a third-party. Settlements for casualty/liability coverages can extend for long periods of time as claims are often reported and ultimately paid or settled years after the related loss events occur.

Ark has recently added new products and lines of business to its portfolio, as it focuses on profitable business opportunities while carefully managing underwriting risk. Ark also leads certain Lloyd’s market consortia, including two that target renewable energy clients including wind farms, solar plants, hydroelectric plants, geothermal plants and wave and tidal projects, as well as others that focus on property and power outage coverages.

The following table presents Ark’s gross written premiums by line of business for the years ended December 31, 2025, 2024 and 2023:

| Millions | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Property | **$1,178.0** | $1,080.8 | $917.0 |
| Specialty | **646.7** | 450.0 | 436.6 |
| Marine & Energy | **453.6** | 449.6 | 375.7 |
| Casualty | **168.8** | 130.6 | 98.7 |
| Accident & Health | **110.1** | 96.0 | 70.4 |
| Total gross written premiums | **$2,557.2** | $2,207.0 | $1,898.4 |

4

A description of Ark’s business written within each line of business follows:

### Property

Ark’s property business is underwritten on both an insurance and reinsurance basis covering the financial consequences of accidental losses to an insured’s property, such as a business’s building, inventory and equipment, or personal property. Coverages provided include all risks of direct physical loss or damage, business interruption and natural and non-natural catastrophe perils. Ark’s property insurance business consists primarily of direct and facultative contracts, line slips and MGA binding authorities. Ark’s property insurance business is underwritten on a worldwide basis with a focus on excess & surplus lines in the United States and on large international accounts. Ark’s property reinsurance business consists primarily of treaty reinsurance underwritten on a catastrophe excess of loss, per risk excess and proportional basis. Ark’s property reinsurance business is underwritten on a worldwide basis with particular focus on risks in the United States and Europe. Ark also underwrites structured property business, which provides reinsurance capacity to primary fronting insurance companies, net after inuring reinsurance, with a limited downside risk profile that is managed through aggregated collateralized limits.

### Specialty

Ark’s specialty business is underwritten on both an insurance and reinsurance basis covering a range of individual risks and treaties primarily including aviation, contingency, cyber, fine art & specie, mortgage, nuclear, political and credit, space, surety as well as terrorism and political violence. Ark’s specialty insurance and reinsurance business is underwritten on a worldwide basis.

#### Aviation

Aviation insurance primarily covers airlines and general aviation for loss of, or damage to, aircraft hull and ensuing passenger and third-party liability. Perils include war and war-like actions such as terrorism, hijacking, confiscation, expropriation, nationalization and deprivation. Additionally, liability arising out of non-aircraft operations such as hangars and airports may be covered.

#### Contingency

Contingency insurance primarily covers cancellation and abandonment of events, non-appearance, prize indemnity and film and television insurance. Ark’s contingency insurance and reinsurance business is underwritten on a worldwide basis.

#### Cyber

Cyber insurance primarily covers the physical damage and liabilities arising from cyber attacks, including coverage for ransomware, loss of data, incident response costs, business interruption and third-party liabilities.

#### Fine Art & Specie

Fine art & specie insurance primarily covers loss to fine art, specie, cash in transit and vault and jewelers’ block risks as a result of theft or damage in transit or at exhibition.

#### Mortgage

Mortgage insurance covers financial guarantee and credit risks between a lending institution and a borrower designed to address responsibility for debt payments and default. Ark underwrites a reinsurance portfolio supporting government-sponsored enterprises (Fannie Mae and Freddie Mac) and private mortgage insurers on both a proportional and excess of loss basis.

#### Nuclear

Nuclear insurance covers country specific nuclear pools and companies and institutions with nuclear exposure excluded from standard property and casualty policies for coverage of physical damage and third-party liability.

#### Political and Credit

Political and credit insurance primarily covers risks relating to the confiscation, expropriation, nationalization and deprivation of insured assets due to war, political or government action as well as contract frustration and non-payment by obligors.

#### Space

Space insurance primarily covers loss of, or damage to, satellites during launch and in orbit, including faulty design that leads to early loss of operating life. Ark’s space insurance is primarily written through binders supporting specialized, technical MGAs.

#### Surety

Surety insurance covers financial guarantee risks between a bond issuer, principal and obligee designed to address responsibility for debt payments, default or other financial obligations. Ark underwrites this portfolio on a reinsurance basis, primarily excess of loss, for U.S.-domiciled clients. The underlying assureds cover a variety of industries including construction, oil & gas, hotel & leisure and transportation projects.

#### Terrorism and Political Violence

Terrorism and political violence insurance primarily covers physical loss or damage and threat thereof, including ensuing loss through business interruption, caused by declared terror events, political violence and war and war-like actions in developed and developing countries around the world.

### Marine & Energy

Ark’s marine & energy business is underwritten on both an insurance and reinsurance basis primarily covering marine hull, cargo, specie, marine & energy liabilities and upstream energy platform physical damage and liability. Marine hull consists primarily of coastal and ocean-going vessels and covers worldwide risks on an all perils or total loss only basis together with lighter craft, including yachts. Cargo consists of worldwide transits and moveable goods with a particular emphasis on bulk cargo, project cargo and pre-launch satellite risks. Specie is the transit and storage of high value goods including semi-precious and precious metals. Marine & energy liabilities consist of liability risks arising from doing business in their respective industries including liabilities arising from pollution and damage covered by protection and indemnity clubs, including for example the International Group of Protection & Indemnity Clubs. Upstream energy platform physical damage and liability covers a variety of oil and gas industry construction, exploration and production risks.

Ark’s marine & energy insurance business consists of direct and facultative risks written primarily in the open market, as well as through line slips and MGA binding authorities. Ark’s marine & energy reinsurance business consists of treaty reinsurance underwritten on both a proportional and excess of loss basis. Ark’s marine & energy insurance and reinsurance business is underwritten on a worldwide basis.

### Casualty

Ark’s casualty business is underwritten on an insurance and reinsurance basis primarily covering medical malpractice, professional liability and general liability. Ark’s casualty insurance business is generally written on an excess of loss and primary basis for a wide range of U.S. and non-U.S. companies, including (i) public entities, (ii) energy, transportation, chemical, manufacturing and construction companies and (iii) legal, accounting, consulting, architectural and engineering firms. Ark’s casualty reinsurance business is underwritten on an excess of loss and proportional treaty basis.

### Accident & Health

Ark’s accident & health business is underwritten on both an insurance and reinsurance basis covering a wide range of personal accident, sickness, disability, travel, short-term life, health and medical insurance and reinsurance risks. Ark’s accident & health insurance and reinsurance business consists of direct and facultative contracts written under the binding authority of external MGAs and through Accident & Health Underwriting Limited (“AHU”), Ark’s wholly-owned MGA domiciled in the United Kingdom. Ark’s accident & health insurance and reinsurance business is underwritten on a worldwide basis.

### Geographic Concentration

The following table shows Ark’s gross written premiums by geographic region based on the location of Ark’s underwriting offices for the years ended December 31, 2025, 2024 and 2023:

| Millions Gross written premiums by country | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| United Kingdom | **$1,404.7** | $1,229.5 | $1,027.8 |
| Bermuda | **1,152.5** | 977.5 | 870.6 |
| Total | **$2,557.2** | $2,207.0 | $1,898.4 |

6

### Marketing and Distribution

Ark offers its products and services through a network of brokers, MGAs and reinsurance intermediaries (collectively, “insurance and reinsurance intermediaries”). In the United Kingdom, Ark operates through the Syndicates with Lloyd’s approved brokers and MGAs. In Bermuda, Ark primarily derives its reinsurance business through insurance and reinsurance intermediaries that represent the ceding company and its insurance business through brokers based in Bermuda and London. Ark pays commissions to brokers, MGAs and reinsurance intermediaries as compensation for facilitating the flow and processing of business, typically on industry standard percentages of premium underwritten. In addition, Ark pays certain MGAs profit commissions based on the underwriting profit of the business they produce.

During the years ended December 31, 2025, 2024 and 2023, Ark received a significant portion of its gross written premiums from five insurance and reinsurance intermediaries. The following table shows the proportion of business produced by the top five insurance and reinsurance intermediaries for the years ended December 31, 2025, 2024 and 2023:

| Gross written premiums by insurance and reinsurance intermediary | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Marsh & McLennan Companies, Inc. | **24.3%** | 25.8% | 27.5% |
| Arthur J. Gallagher & Co | **15.2** | 12.5 | 16.9 |
| Aon plc | **12.4** | 13.4 | 16.7 |
| Howden Insurance Group | **8.7** | 6.4 | 4.6 |
| Willis Towers Watson plc | **4.1** | 4.9 | 5.0 |
| Total proportion of business produced by the top five insurance and reinsurance intermediaries | **64.7%** | 63.0% | 70.7% |

### Underwriting and Pricing

Ark aims to build a diversified and balanced portfolio of risks that generates an underwriting profit each year. Ark believes in a disciplined underwriting strategy that aims to consistently outperform the market. In hard market conditions, Ark aims to grow premiums, as pricing, terms and conditions and limit deployment are more favorable and can lead to enhanced returns on capital. In soft markets, Ark is willing to reduce its business volume when pricing, terms and conditions and limit deployment can make it more difficult to achieve an adequate return on capital. Ark is willing to forgo business if it believes it is not priced appropriately for the exposure or risk assumed.

Ark operates an underwriting controls framework which includes individual underwriting authorities, continuous quality monitoring and peer review of risks. The framework aims to ensure a high quality of underwriting through monitoring of pricing and rate change, contract certainty and appropriate terms and conditions. The nature of delegated underwriting naturally increases the risk of underwriting, through the ability of third parties being able to bind Ark to risks without detailed review of the risk involved. This risk is mitigated through the application of strict underwriting guidelines, managed by a dedicated team within the Ark compliance department. This team reviews MGA and third-party binding authority approvals pre-bind and monitors a program of audits to ensure compliance with regulations and guidelines.

Ark uses bespoke pricing models for each of the products that it underwrites. These pricing models seek to generate a pricing metric required to achieve an acceptable return on capital for each class of business, and each of the risks priced therein. These models rely on several factors depending on the class of business, including exposure analysis, historical experience, estimates of future loss costs, claims experience and natural catastrophe outlook, including the physical risk of climate change and inflation. See “**Ark — Catastrophe Risk Management and Reinsurance Protection”** on page 8.

Ark actively monitors price adequacy at various points between individual risks and the portfolio level to measure and evaluate overall performance. In addition, Ark updates rates to achieve targeted returns on capital at an individual risk as well as portfolio level to enhance return on capital.

### Competition

Specialized lines of insurance and reinsurance are highly competitive. Ark competes with other Lloyd’s syndicates, London market participants and major U.S., Bermuda, European and other international insurance and reinsurance companies. The significant competitive factors for most products are price, terms and conditions, broker relationships, underwriting service, financial strength rating and claims service. Ark competes with insurance and reinsurance companies who operate in the Bermuda and Lloyd’s markets such as:

- Bermuda insurance and reinsurance market: American International Group, Inc., Arch Capital Group Ltd., Ascot Group Ltd., Aspen Insurance Holdings Ltd., Chubb Ltd., Everest Re Group, Markel Group, Inc., RenaissanceRe Holdings Ltd., Sompo Holdings Inc., SiriusPoint Ltd. and others;
- Lloyd’s market: AXIS Capital Holdings Ltd., Beazley plc, Canopius Group Ltd., Convex Group Ltd., Hiscox plc, Lancashire Holdings Ltd., QBE Insurance Group Ltd. and other syndicates.

### Claims Management

Effective claims management is a critical factor in achieving satisfactory underwriting results. Ark maintains an experienced staff of dedicated claims handlers and loss adjusters. These individuals seek to ensure that Ark has the appropriate level of expertise to handle complex claims. Within the claims departments, Ark also uses various shared services. These include third-party claims administrators, particularly for lower value, less specialized claims (for example in Ark’s MGA-produced business), subrogation and recovery support and legal representation.

For business written in the Lloyd’s market, claims handling and case reserves are established in accordance with the applicable Lloyd’s Claim Scheme and Lloyd’s Claims Management Principles and Oversight Framework.

### Catastrophe Risk Management and Reinsurance Protection

### Catastrophe Risk Management

#### Ark

Ark has exposure to losses caused by unpredictable catastrophic events all over the world including natural and other disasters such as hurricanes, windstorms, earthquakes, floods, wildfires, tornadoes, tsunamis and severe weather. Catastrophes can also include large losses driven by public health crises, terrorist attacks, war and war-like actions, explosions, infrastructure failures and cyber attacks. The extent of a catastrophe loss is a function of both the severity of the event and total amount of insured exposure to the event, as well as the coverage provided to customers. Increases in the value and concentration of insured property or insured employees, the effects of inflation, changes in weather patterns and increased terrorism and war and war-like actions could increase the future frequency and/or severity of claims from catastrophic events. Climate change, which is characterized by higher temperatures, sea level rise and more extreme weather events including droughts, heavy storms, wildfires and stronger hurricanes, increases the frequency and severity of certain major natural catastrophes. There is also a growing threat of cyber catastrophes due to the increasing interconnectivity of global systems and artificial intelligence.

Ark seeks to manage its exposure to catastrophic losses by limiting and monitoring the aggregate insured value of policies in geographic areas with exposure to catastrophic events and by buying reinsurance. To manage, monitor and analyze insured values and potential losses, Ark utilizes proprietary and third-party catastrophe management software to estimate potential losses for many different catastrophe scenarios. Ark incorporates the physical risk of climate change in its underwriting process through sensitivity and stress testing of its catastrophe models, including increased frequency of U.S. windstorms and the implications of storm surge.

Ark licenses third-party global property catastrophe models from Risk Management Solutions Inc. and Karen Clark & Company, as well as utilizes its own proprietary models to calculate expected probable maximum loss (“PML”) estimates from various property and non-property catastrophe scenarios. Ark prices property catastrophe contracts using its own proprietary models, utilizing inputs from third-party software and other data as appropriate. For business that Ark determines to have exposure to catastrophic perils, as part of its underwriting process, it models and evaluates the exposure to assess whether there is an appropriate premium charged for the exposure assumed.

Ark’s two largest natural catastrophe PML zones on a per occurrence basis for a 1-in-250 year event, as measured on a net after-tax exposure basis, are U.S. windstorm and U.S. earthquake. The net after-tax exposure is net of amounts ceded to reinsurers and reinstatement premiums. Different perils are more prevalent at different times of the year, and Ark tailors its outwards reinsurance program to incept accordingly. Once the placement of Ark’s 2026 outwards reinsurance program is completed, Ark expects its net after-tax peak exposure for a 1-in-250 year event related to its largest PML zone to approximate 20-35% of its tangible capital (tangible book value plus debt). Ark’s tangible capital was $1,833 million as of December 31, 2025.

In addition, Ark also has loss exposures to other global natural catastrophe events including, but not limited to, Japanese earthquakes, Japanese windstorms, European windstorms and U.S. wildfires.

Ark’s estimates of potential losses are dependent on many variables, including assumptions about storm intensity, storm surge and loss amplification, loss adjustment expenses and insurance-to-value in the aftermath of weather-related catastrophes. In addition, Ark has to account for quality of data provided by insureds. Accordingly, if the assumptions are incorrect, the losses Ark might incur from an actual catastrophe could be materially different than the expectation of losses generated from modeled catastrophe scenarios. There could also be unmodelled losses which exceed the amounts estimated for U.S. windstorm and U.S. earthquake catastrophes.

Outside of natural catastrophe losses, Ark has exposure to non-natural or man-made large losses. The current largest exposures are cyber, offshore energy production platforms, aviation, terrorism events, war and war-like actions and political risk. Ark uses data from clients and combines this with accumulation tools and PML assessments to obtain potential loss scenarios.

Cyber losses can be derived from a number of scenarios that include major data security breach on large multinational organizations, business blackout from cyber attack on power generation and distribution facilities, malicious attack on cloud service provider data center and ransomware contagion across both individual and multiple corporations. Catastrophic losses in respect of offshore energy production platforms can include physical damage, business interruption, pollution liability, extra expenses and control of oil or gas flow therefrom. Aviation can include physical damage, passenger and third-party liability, hijacking, confiscation, expropriation, nationalization and deprivation. Terrorism and war and war-like actions can include physical damage, business interruption, liability, loss of life and fire following at locations around the world either in a single city or in coordinated attacks across multiple cities, countries or regions. Political and credit risk scenarios can include confiscation, expropriation, nationalization and deprivation of assets, non-payment of financial obligations and mortgage default. Ark estimates its largest net after-tax loss from non-natural/man-made loss scenarios to be less than 10% of its tangible capital.

#### WM Outrigger Re

WM Outrigger Re has exposure to losses caused by unpredictable catastrophic events including natural and other disasters all over the world such as hurricanes, windstorms, earthquakes, floods, wildfires, tornadoes, tsunamis, severe weather and related infrastructure failures. The extent of a catastrophe loss is a function of both the severity of the event and total amount of insured exposure to the event, as well as the coverage provided to customers. Increases in the value and concentration of insured property, the effects of inflation and changes in weather patterns could increase the future frequency and/or severity of claims from catastrophic events. Climate change, which is characterized by higher temperatures, sea level rise and more extreme weather events including droughts, heavy storms, wildfires and stronger hurricanes, increases the frequency and severity of certain major natural catastrophes.

WM Outrigger Re is not providing reinsurance to GAIL for the 2026 underwriting year. However, WM Outrigger Re remains exposed to natural catastrophe events that occur prior to the expiration of the 2025 underwriting year on June 30, 2026. WM Outrigger Re’s two largest remaining natural catastrophe PML zones on a per occurrence basis for a 1-in-250 year event as of January 2026, as measured net of reinstatement premiums, are U.S. earthquake and Japanese windstorm. These two loss events would each represent less than 1% of White Mountains’s common equity. WM Outrigger Re’s obligations under its reinsurance agreement with GAIL are subject to an aggregate limit equal to the assets in the collateral trust at any point in time.

#### Reinsurance Protection

As part of its enterprise risk management function, Ark purchases reinsurance for risk mitigation purposes. Ark utilizes reinsurance and retrocession agreements to reduce earnings volatility, protect capital, limit its exposure to risk concentration and accumulation of loss and manage within its overall internal risk tolerances or those set and agreed by regulators, ratings agencies and Lloyd’s. Ark also enters into reinsurance and retrocession agreements to reduce its liability on individual risks and enable it to underwrite policies with higher limits where Ark believes this has a broader business benefit.

Ark seeks to protect its downside risk from catastrophes and large loss events by purchasing reinsurance, including quota share and excess of loss protections, aggregate covers and industry loss warranties. Ark also considers alternative structures such as collateralized reinsurance, retrocessional reinsurance and catastrophe bonds.

During the fourth quarter of 2023, 2024 and 2025, Ark renewed its collateralized quota share agreements with Outrigger Re Ltd., a Bermuda special purpose insurer, covering Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2024, 2025 and 2026 underwriting years, respectively.

The purchase of reinsurance does not discharge Ark from its primary liability for the full value of its policies, and thus the collectability of balances due from Ark’s reinsurers is critical to its financial strength. Ark monitors the financial strength and ratings of its reinsurers on an ongoing basis. See **Note 6 — “Third-Party Reinsurance”** on page F-47 for a discussion of Ark’s top reinsurers.

### Ark’s Loss and LAE Reserves

Ark establishes loss and LAE reserves that are estimates of amounts needed to pay claims and related expenses in the future for insured events that have already occurred, including both reported and unreported claims. Loss reserves are established due to the significant periods of time that may occur between the occurrence, reporting and payment of a loss. The process of estimating reserves involves a considerable degree of judgment by management and is inherently uncertain. See “**CRITICAL ACCOUNTING ESTIMATES — Loss and LAE Reserves”** on page 90 and **Note 5 — “Loss and Loss Adjustment Expense Reserves”** on page F-36 for a full discussion regarding Ark’s loss reserving process.

### HG GLOBAL

The HG Global segment consists of HG Global and, prior to its deconsolidation on July 1, 2024, the consolidated results of Build America Mutual Assurance Company (“BAM”). See **Note 2 — “Significant Transactions”** on page F-19.

HG Global was established to fund the startup of BAM and provide reinsurance protection to BAM’s municipal bond insured portfolio. HG Global, together with its subsidiaries, funded the initial capitalization of BAM through the purchase of $503 million of surplus notes issued by BAM (the “BAM Surplus Notes”). HG Global, through its reinsurance subsidiary, HG Re, is a party to a first-loss reinsurance treaty (“FLRT”) with BAM, under which HG Re provides first-loss protection of up to 15%-of-par outstanding for each policy assumed from BAM. HG Re is only licensed to provide reinsurance to BAM. HG Re is required to provide reinsurance on policies that fall within the FLRT underwriting guidelines agreed upon by HG Re.

BAM is the first and only mutual municipal bond insurance company in the United States. By insuring the timely payment of principal and interest on municipal bonds, BAM provides market access to, and lowers interest expense for, issuers of municipal bonds used to finance essential public purpose projects. As a mutual insurance company, BAM is owned by and operated for the benefit of its members, the municipalities whose debt issuances are insured by BAM. BAM is domiciled in New York and is regulated by the New York State Department of Financial Services (“NYDFS”).

White Mountains does not have an ownership interest in BAM. However, through June 30, 2024, White Mountains was required to consolidate BAM’s results in its financial statements because BAM is a variable interest entity (“VIE”) for which White Mountains was the primary beneficiary. BAM’s results were all attributed to noncontrolling interests. On July 1, 2024, HG Re and BAM amended the FLRT with respect to certain governance rights held by HG Re. As a result, and in combination with other governance changes at BAM, White Mountains concluded that it no longer has the power to direct BAM’s activities that most significantly impact its economic performance and is no longer BAM’s primary beneficiary. Accordingly, as of July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, BAM’s results of operations, are presented within the HG Global segment. See **Note 2 — “Significant Transactions”** on page F-19.

HG Global has two primary sources of cash flows: (i) interest payments on the BAM Surplus Notes that are made outside the Collateral Trusts and (ii) releases of excess balances from the Collateral Trusts. See “**Collateral Trusts”** on page 12.

As of December 31, 2025 and 2024, White Mountains reported $1,237 million and $1,179 million of total assets and $210 million and $253 million of total equity related to HG Global. HG Global’s total equity attributable to White Mountains’s common shareholders after intercompany eliminations related to preferred dividends payable to White Mountains and intercompany debt was $756 million and $729 million as of December 31, 2025 and 2024. As of December 31, 2025 and 2024, White Mountains owned 96.9% of HG Global’s preferred equity and 88.4% of its common equity. As of December 31, 2025 and 2024, White Mountains reported $(18) million and $(13) million of noncontrolling interests related to HG Global.

### Reinsurance Treaties

HG Global provides reinsurance exclusively to BAM. Through the reinsurance relationship with BAM, HG Global maintains a direct dialogue and line of sight into key operations, including the application of both BAM’s underwriting guidelines and the FLRT underwriting guidelines, continuous portfolio monitoring, credit surveillance and claims paying resources.

HG Global reinsures all BAM policies that meet the FLRT underwriting guidelines. This has resulted in a portfolio with a focus on prudent single risk limits for small-to-medium sized, public investment grade municipal bonds in the United States (primarily in the AA, A and BBB categories in low-risk, stable sectors) that are issued to finance essential public purpose projects, such as schools, utilities and transportation facilities. White Mountains believes that municipal bonds insured by BAM have strong appeal to retail investors, who buy smaller, less liquid issuances, have less portfolio diversification and have fewer credit differentiation skills and analytical resources than institutional investors.

HG Re, through its reinsurance treaties with BAM, is exposed to climate-related events to the extent that those events impact a municipal issuer’s ability to service its debt obligations. Under the FLRT underwriting guidelines, BAM incorporates climate change risk in its credit underwriting process. In doing so, BAM considers both the short-term economic impact from climate change-related severe weather events (including flooding, wildfires, drought, windstorms and tornadoes), as well as longer-term impacts on population and property values from rising sea levels and changing temperature patterns.

### FLRT

Under the FLRT, HG Re provides first-loss reinsurance protection of up to 15%-of-par outstanding for each policy assumed from BAM. For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds. HG Re is required to provide reinsurance on policies that fall within the FLRT underwriting guidelines agreed upon by HG Re.

BAM charges an insurance premium on each municipal bond insurance policy it underwrites. Historically, approximately 55% of the total insurance premium charged by BAM has been a member surplus contribution (“MSC”), and the remainder is a risk premium. In return for the reinsurance provided, HG Re receives approximately 60% of the risk premium charged, which is net of a ceding commission.

The FLRT is a perpetual agreement with terms that can be renegotiated every five years. For the next renegotiation period, either party may provide notice during 2028 to trigger a renegotiation that would take effect on January 1, 2030. If the parties are unable to mutually agree to amended terms, the dispute is resolved through arbitration, according to certain principles agreed to by the parties. Amended contract terms must be approved by the NYDFS. Should BAM consider the amended terms unacceptable, it has the option to purchase HG Re or cause another reinsurer to purchase HG Re, at fair value.

In addition, the FLRT provides HG Holdings Ltd., a subsidiary of HG Global, the right to designate two directors for election to BAM’s Board of Directors.

For the year ended December 31, 2025, HG Re recognized gross written premiums of $61 million and earned premiums of $31 million. Prior to the deconsolidation of BAM on July 1, 2024, HG Re’s reinsurance balances under the FLRT eliminated in White Mountains’s consolidated financial statements. For the period from July 1, 2024 to December 31, 2024, HG Re recognized gross written premiums of $32 million and earned premiums of $15 million during the year ended December 31, 2024.

### XOLT

HG Re is also party to an excess of loss reinsurance agreement (the “XOLT”) with BAM under which HG Re provides last-dollar protection for exposures on municipal bonds insured by BAM in excess of the NYDFS single issuer limits. As of December 31, 2025, the XOLT is subject to an aggregate limit equal to the lesser of $125 million or the assets held in the supplemental collateral trust (the “Supplemental Trust”) at any point in time. The XOLT is accounted for using deposit accounting, as the agreement does not meet the risk transfer requirements necessary to be accounted for as reinsurance. Accordingly, any financing revenues related to the XOLT are recorded in other revenues,

Prior to the deconsolidation of BAM on July 1, 2024, HG Re’s reinsurance balances under the XOLT eliminated in White Mountains’s consolidated financial statements. For the year ended December 31, 2025 and for the period from July 1, 2024 to December 31, 2024, other revenues recognized by HG Re related to the XOLT were insignificant.

### Collateral Trusts

HG Re’s obligations under the FLRT are subject to an aggregate limit equal to the assets in two collateral trusts, the Supplemental Trust and the Regulation 114 Trust (together, the “Collateral Trusts”), at any point in time.

On a monthly basis, BAM deposits cash equal to ceded premiums net of ceding commissions, due to HG Re under the FLRT directly into the Regulation 114 Trust. The Regulation 114 Trust target balance is equal to HG Re’s unearned premiums and unpaid loss and LAE reserves, if any. If, at the end of any quarter, the Regulation 114 Trust balance is below the target balance, funds will be withdrawn from the Supplemental Trust and deposited into the Regulation 114 Trust in an amount equal to the shortfall. If, at the end of any quarter, the Regulation 114 Trust balance is above 102% of the target balance, funds will be withdrawn from the Regulation 114 Trust and deposited into the Supplemental Trust. The Regulation 114 Trust balance as of December 31, 2025 and 2024 was $399 million and $352 million, which consisted of cash, investments and accrued investment income.

The Supplemental Trust target balance is $603 million, less the amount of cash and securities in the Regulation 114 Trust in excess of its target balance (the “Supplemental Trust Target Balance”). If, at the end of any quarter, the Supplemental Trust balance exceeds the Supplemental Trust Target Balance, such excess may be distributed to HG Re. The distribution will be made first as an assignment of accrued interest on the BAM Surplus Notes and second in cash and/or fixed income securities. For the year ended December 31, 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of $30 million of accrued interest on the BAM Surplus Notes and a cash distribution of $31 million. For the year ended December 31, 2024, HG Re received a distribution from the Supplemental Trust of $80 million, which consisted of an assignment of $59 million of accrued interest on the BAM Surplus Notes and a cash distribution of $21 million.

As the BAM Surplus Notes are repaid over time, the BAM Surplus Notes will be replaced in the Supplemental Trust by cash and fixed income securities. The Supplemental Trust balance as of December 31, 2025 and 2024 was $607 million and $598 million, which included $323 million and $289 million of cash, investments and accrued investment income, $277 million and $301 million of BAM Surplus Notes at nominal value and $7 million and $8 million of accrued interest receivable on the BAM Surplus Notes at nominal value.

As of December 31, 2025 and 2024, the Collateral Trusts held total assets of $1,007 million and $950 million.

### BAM Surplus Notes

Through June 30, 2024, the interest rate on the BAM Surplus Notes was a variable rate equal to the one-year U.S. Treasury rate plus 300 basis points, set annually, with each payment applied pro rata between outstanding principal and interest. Accordingly, in 2024, the interest rate on the BAM Surplus Notes was 8.2% through June 30, 2024. Effective July 1, 2024 and through maturity, HG Global and BAM amended the interest rate on the BAM Surplus Notes to be 10.0%, with a higher proportion of each payment to be applied to outstanding principal.

Under its agreements with HG Global, BAM is required to seek regulatory approval to pay principal and interest on the BAM Surplus Notes only to the extent that its remaining qualified statutory capital and other capital resources continue to support its outstanding obligations, its business plan and its “AA/stable” rating from Standard & Poor’s. No payment of principal or interest on the BAM Surplus Notes may be made without the approval of the NYDFS.

During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust.

During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust.

During 2023, HG Global received a cash payment of principal and interest on the BAM Surplus Notes of $27 million. Of this payment, $18 million was a repayment of principal held in the Supplemental Trust, $2 million was a payment of accrued interest held in the Supplemental Trust and $7 million was a payment of accrued interest held outside the Supplemental Trust.

As of December 31, 2025 and 2024, the principal balance on the BAM Surplus Notes was $277 million and $301 million and total interest receivable on the BAM Surplus Notes was $214 million and $195 million, all at nominal value.

Prior to the deconsolidation of BAM on July 1, 2024, the BAM Surplus Notes, including accrued interest receivable, were classified as intercompany notes carried at nominal value, which eliminated in consolidation. Upon deconsolidation, White Mountains elected the fair value option for the BAM Surplus Notes. As of December 31, 2025 and 2024, the fair value of the BAM Surplus Notes was $339 million and $382 million. The decline was driven by a $38 million decrease in fair value and $35 million in cash payments of principal and interest, partially offset by $30 million of accrued interest. See “**BAM Surplus Notes”** under “**CRITICAL ACCOUNTING ESTIMATES — Fair Value Measurements”** on page 88.

### Competition/Pricing

Certain sectors of the municipal bond insurance industry are highly competitive. HG Re is only licensed to provide reinsurance to BAM. Accordingly, HG Re, through its reinsurance treaties with BAM, is indirectly exposed to this competition.

BAM’s primary competitor is Assured Guaranty Ltd. (“Assured”). BAM and Assured each seek to differentiate themselves through risk selection, financial strength ratings, claims paying resources and underwriting strategies. BAM believes it has a number of distinct competitive advantages, and that, over time, its mutual structure will deliver a cost of capital advantage relative to its stock company competitor.

Pricing (i.e., premium level) is affected by a number of factors, including interest rate levels, credit spreads, trading value and capture rate (i.e., the percentage of total interest savings captured in the form of insurance premium). All else being equal, pricing is generally higher when interest rates are higher, credit spreads are wider, BAM’s trading value is higher relative to competitors and the capture rate is higher.

### Insured Portfolio

Under the FLRT, HG Re provides first-loss reinsurance protection of up to 15%-of-par outstanding for each policy assumed from BAM. For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds.

The following table presents HG Re’s insured portfolio by asset class as of December 31, 2025 and 2024:

| Millions Sector | December 31, 2025 Outstanding Par Value of Policies Assumed | Weighted Average Credit Rating (1) | December 31, 2024 Outstanding Par Value of Policies Assumed | Weighted Average Credit Rating (1) |
| --- | ---: | --- | ---: | --- |
| General obligation | **$10,757.7** | **A** | $9,811.0 | A |
| Utility | **3,079.3** | **A** | 2,653.3 | A |
| Dedicated tax | **2,001.4** | **A** | 1,858.0 | A |
| General fund | **1,709.5** | **A+** | 1,608.1 | A+ |
| Higher education | **1,585.3** | **A-** | 1,363.2 | A- |
| Enterprise systems | **1,426.7** | **A** | 1,209.7 | A |
| Total insured portfolio | **$20,559.9** | **A** | $18,503.3 | A |

(1) The weighted average credit ratings are based on Standard & Poor’s credit ratings, or if unrated by Standard & Poor’s, the Standard & Poor’s equivalent of credit ratings provided by Moody’s Investor Service (“Moody’s”). HG Re’s weighted average credit rating is calculated using its outstanding par value of policies assumed.

The following tables present HG Re’s ten largest exposures based upon the par value of policies assumed as of December 31, 2025 and 2024:

*$ in Millions*

|  | December 31, 2025 Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed | Credit Rating (1) |
| --- | ---: | ---: | --- |
| Metropolitan Transportation Authority (MTA), NY, Mass Transit - Farebox | $87.6 | 0.4% | A |
| City of Sherman, TX, (Grayson County), Combined Water & Sewer | 85.7 | 0.4 | A- |
| New Jersey Transportation Trust Fund Authority, System & Program Bonds, NJ, Gas Tax - State | 84.4 | 0.4 | A |
| City of Chicago, IL (Cook County) | 80.9 | 0.4 | BBB |
| South Carolina Public Service Authority | 77.1 | 0.4 | A- |
| Westfield Washington Schools, IN (Hamilton County) | 74.5 | 0.4 | AA+ |
| Midway Airport, Chicago City of, IL (Cook County), Airport GARB (2023 Supplemental Indenture) | 73.4 | 0.4 | A |
| City of Chicago, IL (Cook County), Sales Tax - Local | 72.5 | 0.4 | A+ |
| Hayward USD, CA (Alameda County) | 71.0 | 0.3 | A+ |
| O'Hare Airport, IL (Cook County) GARB | 70.4 | 0.3 | A+ |
| Total of top ten exposures | **$777.5** | **3.8%** |  |

(1) The credit ratings are based on Standard & Poor’s credit ratings, or if unrated by Standard & Poor’s, the Standard & Poor’s equivalent of credit ratings provided by Moody’s. “AA+” is the second highest, “A+” is the fifth highest, “A” is the sixth highest, “A-” is the seventh highest and “BBB” is the ninth highest of 23 credit ratings assigned by Standard & Poor’s.

*$ in Millions*

|  | December 31, 2024 Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed | Credit Rating (1) |
| --- | ---: | ---: | --- |
| Metropolitan Transportation Authority (MTA), NY, Mass Transit - Farebox | $79.7 | 0.4% | A- |
| Midway Airport, City of Chicago, IL (Cook County), Airport GARB (2023 Supplemental Indenture) | 77.0 | 0.4 | A |
| City of Sherman, TX, (Grayson County), Combined Water & Sewer | 76.4 | 0.4 | A |
| South Carolina Public Service Authority | 73.1 | 0.4 | A- |
| City of Chicago, IL (Cook County), Sales Tax - Local | 71.6 | 0.4 | AA- |
| New Jersey Transportation Trust Fund Authority, System & Program Bonds, NJ, Gas Tax - State | 69.2 | 0.4 | A- |
| Pennsylvania Turnpike Commission, PA, Toll Roads | 64.8 | 0.4 | A+ |
| Port Authority of NY and NJ | 63.0 | 0.3 | AA- |
| State of Illinois, General Obligation Bonds | 61.9 | 0.3 | A- |
| City of Wichita, KS (Sedgwick County), Water & Sewer | 61.6 | 0.3 | AA- |
| Total of top ten exposures | $698.3 | 3.7% |  |

(1) The credit ratings are based on Standard & Poor’s credit ratings, or if unrated by Standard & Poor’s, the Standard & Poor’s equivalent of credit ratings provided by Moody’s. “AA-” is the fourth highest, “A+” is the fifth highest, “A” is the sixth highest and “A-” is the seventh highest of 23 credit ratings assigned by Standard & Poor’s.

The following tables present the geographic distribution of HG Re’s insured portfolio as of December 31, 2025 and 2024:

*$ in Millions*

|  | December 31, 2025 Number of Risks | Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed |
| --- | ---: | ---: | ---: |
| California | 908 | $3,677.7 | 17.9% |
| Texas | 1,268 | 3,388.7 | 16.5% |
| Illinois | 529 | 1,909.4 | 9.3% |
| Pennsylvania | 568 | 1,718.5 | 8.4% |
| New York | 423 | 969.3 | 4.7% |
| New Jersey | 218 | 772.3 | 3.8% |
| Alabama | 221 | 612.3 | 3.0% |
| Ohio | 209 | 600.4 | 2.9% |
| Florida | 98 | 524.0 | 2.5% |
| Indiana | 158 | 509.4 | 2.5% |
| Other States | 1,917 | 5,877.9 | 28.5% |
| Total insured portfolio | **6,517** | **$20,559.9** | **100.0%** |

15

*$ in Millions*

|  | December 31, 2024 Number of Risks | Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed |
| --- | ---: | ---: | ---: |
| California | 891 | $3,336.9 | 18.0% |
| Texas | 1,156 | 2,940.7 | 15.9 |
| Illinois | 499 | 1,721.2 | 9.3 |
| Pennsylvania | 555 | 1,688.2 | 9.1 |
| New York | 421 | 866.3 | 4.7 |
| New Jersey | 212 | 712.7 | 3.9 |
| Alabama | 216 | 563.0 | 3.0 |
| Florida | 99 | 523.3 | 2.8 |
| Ohio | 197 | 494.1 | 2.7 |
| Indiana | 152 | 463.5 | 2.5 |
| Other States | 1,753 | 5,193.4 | 28.1 |
| Total insured portfolio | 6,151 | $18,503.3 | 100.0% |

The following table presents HG Re’s insured portfolio by issuer size of exposure as of December 31, 2025 and 2024:

*$ in Millions*

| Original Par Value of Policies Assumed Per Issuer (1) | December 31, 2025 Number of Risks | Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed | December 31, 2024 Number of Risks | Outstanding Par Value of Policies Assumed | Percent of Total Outstanding Par Value of Policies Assumed |
| --- | ---: | ---: | ---: | ---: | ---: | ---: |
| Less than $1 million | **2,981** | **$1,361.8** | **6.6%** | 2,796 | $1,280.6 | 6.9% |
| $1 to $2 million | **1,284** | **1,850.0** | **9.0** | 1,260 | 1,798.8 | 9.7 |
| $2 to $5 million | **1,313** | **4,175.3** | **20.3** | 1,242 | 3,909.2 | 21.1 |
| $5 to $10 million | **538** | **3,800.1** | **18.5** | 492 | 3,430.3 | 18.5 |
| $10 to $20 million | **239** | **3,319.5** | **16.1** | 217 | 2,952.6 | 16.0 |
| $20 to $50 million | **131** | **4,019.5** | **19.6** | 121 | 3,697.8 | 20.0 |
| Above $50m | **31** | **2,033.7** | **9.9** | 23 | 1,434.0 | 7.8 |
| Total insured portfolio | **6,517** | **$20,559.9** | **100.0%** | 6,151 | $18,503.3 | 100.0% |

(1) The original par value of policies assumed per issuer does not include refunded and re-issued deals.

### Insured Credit Surveillance

HG Re attends BAM’s monthly surveillance committee meetings. The surveillance committee evaluates the credit profile of each insured municipal bond on a periodic basis and places each insured municipal bond into one of four surveillance categories, the last two of which represent insured municipal bonds that are on BAM’s insured credit watchlist. Surveillance category 3 represents insured municipal bonds whose issuers are experiencing financial, legal or administrative issues causing overall credit quality deterioration, but whose probability of generating an insured loss is considered remote. Surveillance category 4 represents insured municipal bonds where a loss is expected or losses have been paid and have not been recovered or are not recoverable. As of December 31, 2025, BAM had assigned one credit to surveillance category 3. BAM has not assigned any credits to surveillance category 4 since inception.

Insured municipal bonds on the watchlist are monitored closely and are subject to BAM’s distressed credit management procedures, including a remediation plan developed in consultation with BAM’s legal counsel and consultants and HG Re. The objectives of any remediation plan are to address the problems the issuer is facing, to address any external factors impacting the credit, to ensure that creditors’ rights are enforced and to cure any breaches that may have occurred with respect to any credit triggers or covenants. BAM may work with other insurers, municipal bondholders and/or interested parties on remediation efforts, as applicable.

### KUDU

Kudu provides capital solutions for boutique asset and wealth managers for a variety of purposes including generational ownership transfers, management buyouts, acquisition and growth finance and legacy partner liquidity. Kudu also provides strategic advice to managers from time to time. Kudu’s capital solutions are generally structured as noncontrolling equity interests in the form of revenue and earnings participation contracts (“Participation Contracts”) and designed to generate immediate cash yields.

Kudu expects to fund new capital deployments predominantly through excess operating cash flows, recycling of certain sales transaction proceeds, and available debt capacity, with additional equity contributions from White Mountains and other existing investors as needed.

As of December 31, 2025 and 2024, White Mountains reported $1,402 million and $1,108 million of total assets and $955 million and $792 million of total equity related to Kudu. As of December 31, 2025 and 2024, White Mountains owned 91.2% and 90.4% of Kudu’s basic units outstanding (77.9% and 77.0% on a fully-diluted/fully-converted basis, taking account of management’s equity incentives) and reported $141 million and $128 million of noncontrolling interests related to Kudu.

### Portfolio

As of December 31, 2025, Kudu had deployed $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, Kudu’s asset and wealth management firms had combined assets under management of approximately $153 billion, spanning a range of asset classes including real estate, wealth management, hedge funds, private equity and alternative credit strategies. Since inception, Kudu’s capital was deployed at an initial average gross cash yield of 9.3% based on expected cash in the first year following deployment.

Kudu’s philosophy is to partner with asset and wealth management firms that exhibit strong cash flow generation and growth. Kudu seeks to provide its solutions across a diverse mix of investment strategies and asset classes in the middle market.

Kudu’s average capital deployment to date has been approximately $39 million, with a range from $14 million to $81 million. Apportioned by manager type, Kudu’s portfolio as of December 31, 2025 was deployed 35% in alternatives, 44% in private capital, 14% in wealth management and 7% in traditional asset management. Kudu prioritizes the private capital segment as the underlying clients of these firms tend to be locked-up for an extended period, which can provide stability of revenues in a potential market downturn.

Kudu is geographically diversified with portfolio companies headquartered in the United States and internationally.

On September 2, 2025, White Mountains acquired a controlling financial interest in Distinguished (the “Distinguished Transaction”). See **Note 2 — “Significant Transactions”** on page F-19.

Distinguished is a full-service MGA and program administrator for specialty property and casualty insurance. Distinguished places insurance across a diversified portfolio of programs broadly grouped into two verticals. The ScaleCo vertical consists of established programs, primarily focused on real estate and hospitality end markets. The GrowthCo vertical consists of start-up programs, focused on a diversified set of specialty property and casualty insurance products across multiple industries. On behalf of its insurance carrier partners, Distinguished typically manages all aspects of the placement process, including product development, marketing, underwriting and policy issuance. Distinguished earns commissions based on the volume and profitability of the insurance that it places. Distinguished does not retain insurance risk.

As of December 31, 2025, White Mountains reported $735 million of total assets and $428 million of total equity related to Distinguished. As of December 31, 2025, White Mountains owned 55.5% of the basic units outstanding of Distinguished (43.6% on a fully-diluted/fully-converted basis, taking account of management’s equity incentives) and reported $132 million of redeemable noncontrolling interests and $74 million of nonredeemable noncontrolling interests related to Distinguished.

### Marketing and Distribution

Distinguished is an MGA and program administrator with delegated binding authorities, and as such, is generally dependent on its carrier partners to bear the insurance risk on the programs designed and underwritten by Distinguished. Distinguished typically expands its programs when market conditions are attractive and shrinks its programs when market conditions are challenging. This practice has led to longstanding insurance carrier partner relationships, in some cases over 20 years. The insurance risk for Distinguished’s programs is supported by 17 insurance carrier partners, with the top three of these carrier partners accounting for 61% of Distinguished’s managed premiums for the year ended December 31, 2025, which includes periods prior to White Mountains’s ownership. White Mountains believes this information is useful in understanding the overall diversification in Distinguished’s capacity.

Distinguished primarily relies on third-party agents and brokers as its sales channel. Substantially all of Distinguished’s products are distributed through third-party agents and brokers who have the principal relationships with policyholders. Agents and brokers have significant influence over renewals, and thus Distinguished’s business model is dependent on its relationships with, and the success of, the agents and brokers with whom Distinguished does business. Distinguished’s programs are supported by over 2,000 agents and brokers, with the top three firms accounting for 10% of Distinguished’s managed premiums for the year ended December 31, 2025, which includes periods prior to White Mountains’s ownership. White Mountains believes this information is useful in understanding the overall diversification in Distinguished’s distribution base.

### Competition

Distinguished operates in a highly competitive property and casualty insurance intermediary industry. Competitors are differentiated based on price, conditions of coverage, loss ratio performance, quality of service, technology and other factors. Distinguished’s primary competitors are typically specialty insurance distribution and underwriting businesses and their agents.

### Managed Premiums and Commission and Fee Revenues

Managed premiums, which represent the total premiums placed by Distinguished, were $188 million for the period from September 2, 2025, the date of acquisition, through December 31, 2025. The following table presents Distinguished’s managed premiums and commission and fee revenues by vertical for the period from September 2, 2025 through December 31, 2025.

| Millions | September 2, 2025 - December 31, 2025 Managed Premiums | Commission and Fee Revenues |
| --- | ---: | ---: |
| ScaleCo | **$141.1** | **$41.3** |
| GrowthCo | **46.8** | **15.4** |
| Total | **$187.9** | **$56.7** |

18

For the year ended December 31, 2025, Distinguished’s total managed premiums were $568 million, which increased 6% compared to the year ended December 31, 2024. This includes periods prior to White Mountains’s ownership of Distinguished, which White Mountains believes is useful in understanding the overall size and growth in Distinguished’s premium base.

### OTHER OPERATIONS

White Mountains’s Other Operations consists of the Company and its wholly-owned subsidiary, WM Capital, its other intermediate holding companies, its wholly-owned investment management subsidiary, WM Advisors, investment assets managed by WM Advisors, its interests in the Bamboo SPV, MediaAlpha, PassportCard/DavidShield, BroadStreet, Elementum, WTM Partners, Enterprise Solutions, the Bamboo CRVs, Other Operating Businesses and certain other assets.

### WM Advisors

As of December 31, 2025, WM Advisors managed and/or provided oversight and administration for substantially all of White Mountains’s fixed maturity investments, short-term investments, common equity securities and other long-term investments.

### Bamboo

On January 2, 2024, White Mountains acquired a controlling financial interest in Bamboo. On December 5, 2025, White Mountains completed the sale of a controlling financial interest in WM Pierce Holdings, Inc. and its subsidiaries, including Bamboo MGA (collectively, the "Bamboo Group"), to affiliates of funds advised by CVC Capital Partners (“CVC”), pursuant to the terms of the securities purchase agreement dated October 2, 2025 (the "Bamboo SPA"). Under the terms of the Bamboo SPA, White Mountains sold approximately 77.3% of its equity interest in Bamboo for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million (the “Bamboo Sale Transaction”). White Mountains’s indirect equity interest is held through the Bamboo SPV. See **Note 2 — “Significant Transactions”** on page F- 19.

As a result of the Bamboo Sale Transaction, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. The Bamboo Group’s assets and liabilities have been presented as held for sale as of December 31, 2024. See **Note 20 — “Held for Sale”** on page F-79.

Bamboo is a capital-light, tech- and data-enabled insurance distribution platform providing homeowners’ insurance and related products to the residential property market in California and, beginning in the third quarter of 2025, in Texas. Bamboo operates primarily through Bamboo MGA, its full-service MGA business, where the company manages all aspects of the placement process on behalf of its fronting and reinsurance carrier partners (“Capacity Providers”), including product development, marketing, underwriting, policy issuance and claims oversight, and it earns commissions based on the volume and profitability of the insurance that it places. Bamboo MGA offers both admitted and non-admitted products. Under its capacity agreements, Bamboo MGA’s commission levels are based on a sliding scale tied primarily to its attritional loss ratio. Bamboo also operates two separate but integrated businesses: (i) a retail agency, within Bamboo MGA, offering ancillary products (e.g., flood, earthquake) on behalf of third parties and (ii) Ide8 Re, Inc. (the “Bamboo Captive”), a U.S.-domiciled captive reinsurer that participates in the underwriting risk of Bamboo’s MGA programs to align interests with Capacity Providers.

As of December 31, 2025, White Mountains had a 27.9% limited partnership interest in the Bamboo SPV. As of December 31, 2025, White Mountains owned 17.2% of the basic units outstanding of Bamboo (14.6% on a fully-diluted/fully-converted basis, taking account of management’s equity incentives) on a look-through basis. As of December 31, 2025, the fair value of White Mountains’s interest in the Bamboo SPV was $250 million.

### MediaAlpha

MediaAlpha is a marketing technology company. It operates a transparent and efficient customer acquisition technology platform that facilitates real-time transactions between buyers and sellers of consumer referrals (i.e., clicks, calls and leads), primarily in the property & casualty, health and life insurance verticals. MediaAlpha generates revenue by earning a fee for each consumer referral sold on its platform. A transaction becomes payable only on a qualifying consumer action, and is not contingent on the sale of a product to the consumer.

White Mountains’s investment in MediaAlpha is accounted for at fair value based on the publicly traded share price of MediaAlpha’s common stock and is presented as a separate line item on the balance sheet.

During the second quarter of 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91.2 million. During the second quarter of 2023, White Mountains completed a tender offer to purchase 5.9 million additional shares of MediaAlpha at a purchase price of $10.00 per share.

As of December 31, 2025, White Mountains owned 17.9 million shares of MediaAlpha, representing a 27.4% basic ownership interest based on the total class A and class B common shares outstanding in MediaAlpha’s Report on Form 10-Q dated October 29, 2025. At the December 31, 2025 share price of $12.95, the fair value of White Mountains’s investment in MediaAlpha was $231 million. As of December 31, 2024, White Mountains owned 17.9 million shares of MediaAlpha, representing a 26.6% basic ownership interest. At the December 31, 2024 share price of $11.29, the fair value of White Mountains’s investment in MediaAlpha was $202 million.

### PassportCard/DavidShield

PassportCard/DavidShield is an international MGA specializing in leisure travel insurance and global expatriate medical insurance. PassportCard/DavidShield delivers digitally-enabled insurance solutions that provide real time funding for covered medical expenses at the point of care.

PassportCard/DavidShield writes two principal product lines: (i) leisure travel insurance (“PassportCard”) and (ii) comprehensive expatriate medical services (“DavidShield”). PassportCard/DavidShield offers these products to both individuals and organizations. Its principal markets include Israel (its home market) as well as the European Union and Australia – servicing over two million insured members in over 180 countries. In Israel, PassportCard/DavidShield operates through a wholly-owned insurance carrier that underwrites policies and cedes substantially all underwriting risk to its highly-rated reinsurance partners. Outside Israel, PassportCard/DavidShield places policies with licensed third-party insurance carriers. PassportCard/DavidShield earns commissions for the placement of policies with its insurance and reinsurance carrier partners and licensing fees for the use of its card-based technology. PassportCard/DavidShield distributes its products through brokers, strategic partnerships and direct-to-consumer digital channels.

There are a number of distinct advantages to the PassportCard/DavidShield insurance solutions that differentiate its business in the marketplace. PassportCard/DavidShield offers its members a proprietary, card-based platform that enables paperless claims processing and immediate payment authorization, reducing reliance on traditional reimbursement models. This technology-driven approach supports enhanced claims control, fraud mitigation and data-informed loss management, thereby contributing to competitive loss ratios for its reinsurance partners and a differentiated customer experience.

By leveraging the regulated payment capabilities and propriety infrastructure of a debit card model, PassportCard/DavidShield has been able to integrate its insurance services with personal travel-related payment functionality. In July 2025, PassportCard/DavidShield launched an integrated Travel Money Payment Card, a solution combining the insurance claims card with a personal travel-focused payment card that enables customers to manage both medical expenses and personal travel spending through the same card.

As a business based in Israel, PassportCard/DavidShield has been affected by the geopolitical environment in the Middle East. Following the events of October 7, 2023 and the resulting war in Gaza, PassportCard/DavidShield experienced a significant decline in revenues relating to its Israeli leisure travel segment. However, Israeli leisure travel revenues placed by PassportCard have gradually recovered and have now surpassed pre-war levels despite intermittent periods of increased geopolitical unrest in the region and reduced capacity from international airline carriers offering service to and from Israel. Meanwhile, the comprehensive expatriate medical insurance placed by DavidShield has remained largely unaffected by the geopolitical environment.

White Mountains’s noncontrolling equity interest in PassportCard/DavidShield is accounted for at fair value within other long-term investments. As of December 31, 2025 and 2024, White Mountains owned 53.8% basic ownership interest of PassportCard/DavidShield (51.5% on a fully-diluted/fully-converted basis). As of December 31, 2025 and 2024, the fair value of White Mountains’s interest in PassportCard/DavidShield was $170 million and $150 million.

### BroadStreet

BroadStreet is an insurance brokerage company with a presence in all 50 U.S. states and ten Canadian provinces. BroadStreet focuses on commercial and personal property & casualty insurance and employee benefits. BroadStreet partners with leading insurance agencies, known as core agency partners. Complementing its M&A capabilities and capital solutions, BroadStreet provides a vast network of market resources, tools and expertise to its core agency partners, working alongside them to drive organic growth and improve agency performance.

On July 18, 2025, White Mountains invested $150 million into BroadStreet through the BroadStreet SPV, alongside co-lead investors Ethos Capital LP and British Columbia Investment Management Corporation. See **Note 2 — “Significant Transactions”** on page F- 19. White Mountains’s noncontrolling equity interest in the BroadStreet SPV is accounted for at fair value using NAV as a practical expedient and is included within other long-term investments. As of December 31, 2025, the fair value of White Mountains’s interest in the BroadStreet SPV was $160 million. As of December 31, 2025, White Mountains had a 10.9% limited partnership interest in the BroadStreet SPV and a less than 5% ownership of BroadStreet on a look-through basis.

### Elementum

Elementum is a third-party registered investment adviser specializing in natural catastrophe insurance-linked securities (“ILS”). Elementum manages separate accounts and pooled investment vehicles across various ILS sectors, including catastrophe bonds, collateralized reinsurance investments and industry loss warranties on behalf of third-party clients.

White Mountains has a noncontrolling equity interest in Elementum, which is accounted for at fair value within other long-term investments. As of December 31, 2025 and 2024, the fair value of White Mountains’s interest in Elementum totaled $35 million. As of December 31, 2025 and 2024, White Mountains had a 26.6% limited partnership interest in Elementum (25.4% on a fully-diluted/fully-converted basis).

White Mountains also has investments in ILS funds managed by Elementum. As of December 31, 2025 and 2024, White Mountains had $50 million and $74 million invested in ILS funds managed by Elementum.

### WTM Partners

In October 2023, White Mountains announced the launch of WTM Partners, which will acquire businesses in non-insurance, non-financial services sectors including essential services, light industrial and specialty consumer. White Mountains expects to deploy up to $500 million of equity capital through WTM Partners over time. WTM Partners deployed $58 million in Enterprise Solutions in 2025, which was the first acquisition by WTM Partners. WTM Partners did not deploy any equity capital in 2024.

### Enterprise Solutions

On April 1, 2025, White Mountains acquired a controlling financial interest in Enterprise Solutions (the “Enterprise Solutions Transaction”). See **Note 2 — “Significant Transactions”** on page F- 19. Enterprise Solutions provides specialty electrical contracting services to commercial and institutional customers. As of December 31, 2025, White Mountains reported $178 million of total assets and $90 million of total equity related to Enterprise Solutions. As of December 31, 2025, White Mountains owned 65.5% of Enterprise Solutions on a basic units outstanding basis (59.0% on a fully-diluted/fully-converted basis, taking account of management’s equity incentives) and reported $31 million of noncontrolling interests.

### Bamboo CRVs

The Bamboo CRVs are special purpose collateralized reinsurance vehicles that provide reinsurance capacity to Bamboo. White Mountains capitalized the Bamboo CRVs by purchasing preference shares that were deposited into collateral trust accounts. The Bamboo CRVs entered into collateralized quota share agreements with certain of Bamboo’s fronting partners to provide reinsurance protection on Bamboo’s admitted and non-admitted business written in the 2025 and 2024 treaty years. As of December 31, 2025, White Mountains’s total commitment to the Bamboo CRVs was $10 million.

### Other Operating Businesses

White Mountains has controlling equity interests in various other operating businesses which are consolidated. As of December 31, 2025, White Mountains reported $87 million of total assets, $54 million of total equity (net of intercompany eliminations) and $6 million of noncontrolling interests related to these businesses. As of December 31, 2024, White Mountains reported $100 million of total assets, $65 million of total equity (net of intercompany eliminations) and $9 million of noncontrolling interests related to these businesses.

White Mountains also has noncontrolling equity interests in various other operating businesses, which are generally accounted for at fair value within other long-term investments. As of December 31, 2025 and 2024, the fair value of these interests totaled $58 million and $49 million.

### INVESTMENTS

White Mountains’s investment philosophy is to maximize long-term, after-tax total returns while taking prudent levels of risk and maintaining a diversified portfolio, subject to White Mountains’s investment guidelines and various regulatory restrictions. Under White Mountains’s investment philosophy, each dollar of after-tax investment income or investment gains (realized or unrealized) is valued equally. White Mountains’s investment philosophy also incorporates Environmental, Social and Governance (“ESG”) considerations. For investment assets actively managed by WM Advisors, thorough credit risk assessments are conducted, utilizing Nationally-Recognized Statistical Rating Organizations research and ratings. For actively managed investment assets sub-advised to third-party registered investment managers, White Mountains only utilizes managers who incorporate ESG factors into their investment processes.

White Mountains maintains a fixed income portfolio that consists primarily of high-quality, short-duration, fixed maturity investments and short-term investments. White Mountains invests in fixed maturity investments that are attractively priced in relation to their investment risks and actively manages the average duration of the fixed income portfolio. As of December 31, 2025, the fixed income portfolio duration, including short-term investments, was 1.5 years. White Mountains has established relationships with select third-party registered investment advisers to manage a portion of its fixed income portfolio.

White Mountains maintains an equity portfolio that consists of common equity securities, its investment in MediaAlpha and other long-term investments. As of December 31, 2025, White Mountains’s portfolio of common equity securities generally consists of international listed equity funds and passive exchange traded funds (“ETFs”). White Mountains’s other long-term investments consist primarily of unconsolidated entities, including Kudu’s Participation Contracts, the Bamboo SPV, PassportCard/DavidShield and the BroadStreet SPV, as well as private equity funds and hedge funds, a bank loan fund and Lloyd’s trust deposits. See “**Portfolio Composition”** on page 76.

### REGULATION

### United States

### Insurance Regulation

Distinguished is licensed in all 50 states as an insurance producer. The distribution of insurance products is a heavily regulated industry subject to regulation and supervision by state regulatory authorities. State insurance laws are often complex and generally grant broad discretion to supervisory authorities in adopting regulations and supervising regulated activities, which generally includes the licensing of insurance brokers and agents, intermediaries and third-party administrators. Our continuing ability to distribute insurance products in the states in which we currently operate is dependent upon our compliance with the rules and regulations promulgated by the regulatory authorities in each of these states.

White Mountains believes that Distinguished is in compliance with all applicable laws and regulations pertaining to its business that would have a material effect on its financial condition or results of operations in the event of non-compliance.

#### Rate Regulations

Nearly all states have insurance laws requiring personal property and casualty insurers to file rating plans, policy or coverage forms and other information with the state’s regulatory authority. In many cases, such rating plans and/or policy or coverage forms must be approved by the regulatory authority prior to use. The speed with which an insurer can change rates in response to competition or in response to increasing costs depends, in part, on whether the rating laws are (i) prior approval, (ii) file-and-use or (iii) use-and-file laws. In states with prior approval laws, the regulator must approve a rate before the insurer may use it. In states with file-and-use laws, the insurer does not have to wait for the regulator’s approval to use a rate, but the rate must be filed with the regulatory authority prior to being used. In states with use-and-file laws, the insurer must file rates within a certain period after the insurer begins to use them. Under all three types of rating laws, the regulator has the authority to disapprove a rate filing. While Distinguished is not an insurer, and thus not required to file its own rating plans with the state's regulatory authority, Distinguished’s commissions are derived from a percentage of the premium rates set by its insurance carrier partners in conjunction with state law, and the sustainability of Distinguished’s business is dependent on such rates.

#### Premium Accounts Held in Trust

Distinguished maintains trust accounts in order to comply with fiduciary requirements under U.S. state insurance laws and regulations relating to premium trust accounts. Under such laws, insurance agencies that do not make immediate remittances to counterparties (such as insurance companies, clients or other producers to which premium, commissions or other amounts are due from time to time) must segregate funds owed to such counterparties, and these funds must be held in trust for the insurance company, client or other relevant third-party payee. Distinguished’s use of trust accounts is routinely subject to audits by its insurance carrier partners and other external auditors.

#### Cybersecurity

Certain of our U.S. operations are subject to federal and state cybersecurity and data privacy laws, including the California Consumer Privacy Act, as amended by the California Privacy Rights Act, and the NYDFS Cybersecurity Regulation. These laws impose requirements relating to the protection of personal information, breach notification, governance, risk management and certification. Compliance with these requirements may increase operating costs, and violations may result in regulatory penalties, litigation and reputational harm.

### Investment Regulation

Kudu Investment Holdings, LLC, a subsidiary of Kudu, is an investment adviser that is registered with the SEC under Section 203 of the United States Investment Advisers Act of 1940.

### Bermuda

### Insurance Regulation

The Insurance Act 1978 of Bermuda and related regulations, as amended (the “Insurance Act”), regulates the insurance

business of HG Re, a special purpose insurer, GAIL, Ark’s wholly-owned Class 4 insurance and reinsurance company and Outrigger Re Ltd., a special purpose insurer. Outrigger Re Ltd. is also registered as a segregated accounts company under the Bermuda Segregated Accounts Companies Act 2000, as amended (the “SAC Act”). The Insurance Act provides that no person may carry on any insurance business in or from within Bermuda unless registered as an insurer under the Insurance Act by the Bermuda Monetary Authority (“BMA”). The BMA, in deciding whether to grant registration, has broad discretion to act as it thinks fit in the public interest. From time to time, HG Re, GAIL and Outrigger Re Ltd. may apply for, and be granted, certain modifications to, or exemptions from, regulatory requirements, which may otherwise apply to them.

The Insurance Act imposes solvency and liquidity standards as well as auditing and reporting requirements and confers on the BMA powers to supervise, investigate and intervene in the affairs of insurance companies. The SAC Act stipulates its own solvency test for the declaration of dividends and distributions for segregated accounts, which takes into account the solvency of each segregated account individually, rather than the solvency of the company itself.

#### Classification

GAIL is registered as a Class 4 insurer. Class 4 insurers carry on general insurance business including excess liability business or property catastrophe, marine & energy, casualty and specialty reinsurance business and have a total statutory capital and surplus of not less than $100 million.

As special purpose insurers, HG Re and Outrigger Re Ltd. are insurers that carry on special purpose business. Special purpose business under the Insurance Act is insurance business under which an insurer fully collateralizes its liabilities to the insured persons through (i) the proceeds of any one or more of (a) a debt issuance where the repayment rights of the providers of such debt are subordinated to the rights of the person insured or (b) some other financing mechanism approved by the BMA; (ii) cash; and (iii) time deposits. Special purpose insurers may be registered to carry on either restricted special purpose business or unrestricted special purpose business. Restricted special purpose business is special purpose business conducted between a special purpose insurer and specific insureds approved by the BMA. Both HG Re and Outrigger Re Ltd. are only able to carry on restricted purpose business.

#### Capital and Solvency Return

As a Class 4 insurer, GAIL is required to file, on an annual basis, a capital and solvency return in respect of its general business, which currently includes, among other items, a statutory economic balance sheet, a schedule of risk management, a catastrophe risk return, a schedule of loss triangles or reconciliation of net loss reserves (where applicable), a schedule of eligible capital and the Enhanced Capital Requirement (“ECR”) as calculated by the Bermuda Solvency and Capital Requirement (“BSCR”) model (or an approved internal model). The BSCR is a mathematical model designed to give the BMA robust methods for determining an insurer’s capital adequacy. Underlying the BSCR is the belief that all insurers should operate on an ongoing basis with a view to maintaining their capital at a prudent level in excess of the minimum solvency margin otherwise prescribed under the Insurance Act. The 2025 BSCR must be filed with the BMA before April 30, 2026; at this time, we believe GAIL will exceed the minimum amount required to be maintained under Bermuda law.

As special purpose insurers, HG Re and Outrigger Re Ltd. are also required to file annually with the BMA a statutory return which includes, among other matters, the statutory financial statements, a statement of control and changes of control, a solvency certificate, an annual statutory declaration, an own-risk assessment, alternative capital arrangements report, cyber risk management report and compliance with sanctions report.

#### Financial Condition Report

As a Class 4 insurer, GAIL is required to prepare and publish a financial condition report (“FCR”), which provides, among other things, details of measures governing the business operations, corporate governance framework and solvency and financial performance of the insurer/insurance group. The FCR will be made available in accordance with the requirements of the Insurance Act.

As special purpose insurers, HG Re and Outrigger Re Ltd. are not subject to this requirement.

#### Minimum Solvency Margin

As a general business insurer, GAIL is required to maintain statutory assets in excess of its statutory liabilities by an amount, equal to or greater than the prescribed minimum solvency margin. The minimum solvency margin that must be maintained by a Class 4 insurer is the greater of (i) $100 million, (ii) 50% of net premiums written (with a credit for reinsurance ceded not exceeding 25% of gross premiums), (iii) 15% of net aggregate loss and loss expense provisions and other insurance reserves or (iv) 25% of the ECR.

As special purpose insurers, HG Re and Outrigger Re Ltd. must maintain a minimum solvency margin whereby their special purpose business assets must exceed their special purpose business liabilities by at least $1.

#### Enhanced Capital Requirement

As a Class 4 insurer, GAIL is required to maintain its available statutory economic capital and surplus at a level at least equal to its ECR. The ECR must at all times equal or exceed the insurer’s minimum solvency margin and may be adjusted in circumstances where the BMA concludes that the insurer’s risk profile deviates significantly from the assumptions underlying its ECR or the insurer’s assessment of its risk management policies and practices used to calculate the ECR applicable to it. While not specifically referred to in the Insurance Act, the BMA has also established a target capital level for each Class 4 insurer equal to 120% of the respective ECR. While a Class 4 insurer is not currently required to maintain its statutory economic capital and surplus at this level, the target capital level serves as an early warning tool for the BMA and failure to maintain statutory capital at least equal to the target capital level will likely result in increased BMA regulatory oversight.

As special purpose insurers, HG Re and Outrigger Re Ltd. are not subject to this requirement.

#### Minimum Liquidity Ratio

The Insurance Act provides a minimum liquidity ratio for general business insurers such as GAIL. An insurer engaged in general business is required to maintain the value of its relevant assets at not less than 75% of the amount of its relevant liabilities. Relevant assets include, but are not limited to, cash and time deposits, quoted investments, unquoted bonds and debentures, investment income due and accrued, accounts and premiums receivable, insurance and reinsurance balances receivable and funds held by ceding reinsurers. Relevant liabilities include, but are not limited to, general business insurance reserves and total other liabilities less deferred income tax and sundry liabilities, letters of credit and guarantees.

As special purpose insurers, HG Re and Outrigger Re Ltd. are not subject to this requirement.

#### Eligible Capital

As a Class 4 insurer, GAIL must maintain available capital in accordance with a “three-tiered capital system” to enable the BMA to better assess the quality of an insurer’s capital resources. All capital instruments are classified as either basic or ancillary capital, which in turn are classified into one of three tiers (Tier 1, Tier 2 and Tier 3) based on their “loss absorbency” characteristics. Eligibility limits are then applied to each tier in determining the amounts eligible to cover regulatory capital requirement levels. Under this regime, not more than certain specified percentages of Tier 1, Tier 2 and Tier 3 capital may be used to satisfy the Class 4 insurers' minimum solvency margin, ECR requirements and target capital level.

As special purpose insurers, HG Re and Outrigger Re Ltd. are not subject to this requirement.

#### Restrictions on Dividends and Reductions of Capital

As a Class 4 insurer, GAIL is prohibited from declaring or paying any dividends if in breach of the required minimum solvency margin or minimum liquidity ratio (the “Relevant Margins”) or if the declaration or payment of such dividend would cause the insurer to fail to meet the Relevant Margins. Further, Class 4 insurers are prohibited from declaring or paying in any financial year dividends of more than 25% of its total statutory capital and surplus (as shown on its previous financial year’s statutory balance sheet) unless it files (at least seven days before payment of such dividends) with the BMA an affidavit stating that it will continue to meet its Relevant Margins. Class 4 insurers must obtain the BMA’s prior approval for a reduction of 15% or more of the total statutory capital as set forth in its previous year’s financial statements. These restrictions on dividends under the Insurance Act are in addition to the solvency requirements under the Companies Act 1981 of Bermuda, as amended (the “Companies Act”). See “**LIQUIDITY AND CAPITAL RESOURCES — Dividend Capacity”** on page 81 for further discussion.

As special purpose insurers, HG Re and Outrigger Re Ltd. are not required to obtain the BMA’s prior approval in connection with any reduction of total statutory capital but are prohibited from declaring or paying a dividend if they are in breach of their minimum solvency margin or if the declaration or payment of such dividend would cause such a breach. The solvency test for the declaration of dividends by WM Outrigger Re, as a segregated account, is evaluated based upon the solvency of WM Outrigger Re, rather than the solvency of Outrigger Re Ltd. as a whole.

#### Insurance Code of Conduct and Insurance Sector Operational Cyber Risk Management Code of Conduct

All Bermuda insurers are required to comply with the BMA’s Insurance Code of Conduct, which establishes duties, requirements and standards to be complied with to ensure each insurer implements sound corporate governance, risk management and internal controls. Failure to comply with these requirements will be a factor taken into account by the BMA in determining whether an insurer is conducting its business in a sound and prudent manner under the Insurance Act and, in the case of GAIL, in calculating the operational risk charge applicable in accordance with the insurer's BSCR model (or an approved internal model).

All Bermuda insurers are also required to comply with the BMA’s Insurance Sector Operational Cyber Risk Management Code of Conduct, which establishes duties, requirements and standards to be complied with by each insurer in relation to operational cyber risk management.

#### Powers of Investigation, Intervention and Obtaining Information

The BMA has certain powers of investigation and intervention relating to insurers and their holding companies, subsidiaries and other affiliates, which it may exercise in the interest of such insurer’s policyholders or if there is any risk of insolvency or of a breach of the Insurance Act or the insurer’s license conditions. The BMA may cancel an insurer’s registration on certain grounds specified in the Insurance Act.

#### Notification of Cyber Reporting Events

Every insurer subject to the Insurance Act must notify the BMA of certain cybersecurity events and provide follow-up reporting. Failure to comply may result in regulatory action.

#### Policyholder Priority

In the event of a liquidation or winding up of an insurer, policyholders’ liabilities receive payment ahead of general unsecured creditors. Subject to the prior payment of preferential debts under the Employment Act 2000 and the Companies Act, the insurance debts of an insurer must be paid in priority to all other unsecured debts of the insurer.

### Certain Other Bermuda Law Considerations

The Company is an exempted company registered under the Companies Act. As a result, the Company is required to comply with the provisions of the Companies Act regulating the payment of dividends and making of distributions from contributed surplus. A company is prohibited from declaring or paying a dividend, or making a distribution out of contributed surplus, if there are reasonable grounds for believing that:

(1) the company is, or would after the payment be, unable to pay its liabilities as they become due; or

(2) the realizable value of the company’s assets would thereby be less than its liabilities.

In addition, the Companies Act regulates return of capital, reduction of capital and any purchase or redemption of shares by the Company.

The Economic Substance Act 2018, as amended (“ESA”) impacts every Bermuda registered entity engaged in a “relevant activity,” requiring impacted entities to maintain a substantial economic presence in Bermuda and to satisfy economic substance requirements. Under the ESA, insurance or holding entity activities (both as defined in the ESA and the Economic Substance Regulations 2018, as amended) are relevant activities. To the extent that the ESA applies to any of our Bermuda entities, we are required to demonstrate compliance with economic substance requirements by filing an annual economic substance declaration with the Bermuda Registrar of Companies. Any entity that must satisfy economic substance requirements but fails to do so could face automatic disclosure to competent authorities in the European Union of the information filed by the entity with the Bermuda Registrar of Companies in connection with the economic substance requirements. Additionally, a company may also face penalties, restrictions or regulation of its business activities and may be struck off as a registered entity in Bermuda for failure to satisfy economic substance requirements. The Company believes it complies with all of the applicable laws and regulations pertaining to economic substance that would have a material effect on its financial condition and results of operations in the event of non-compliance.

### United Kingdom

### PRA and FCA Regulation

As an insurer in the United Kingdom, Ark is dual-regulated by the Financial Conduct Authority (the “FCA”) and the Prudential Regulation Authority (the “PRA”) (collectively, the “U.K. Regulators”). The PRA currently has ultimate responsibility for the prudential supervision of financial services in the United Kingdom. The FCA has responsibility for market conduct regulation. The U.K. Regulators regulate insurers, insurance intermediaries and Lloyd’s. Both the PRA and FCA have substantial powers of intervention in relation to regulated firms.

### Lloyd’s Regulation

Lloyd’s as a whole is authorized by the PRA and regulated by both the FCA and the PRA. Lloyd’s is required to implement certain rules prescribed by the PRA and by the FCA; such rules are to be implemented by Lloyd’s pursuant to its powers under the Lloyd’s Act 1982 relating to the operation of the Lloyd’s market. Lloyd’s prescribes, in respect of its managing agents and corporate and individual members, certain minimum standards relating to their management and control, solvency and various other requirements. If it appears to either the PRA or the FCA that either Lloyd’s is not fulfilling its delegated regulatory responsibilities or that managing agents are not complying with the applicable regulatory rules and guidance, the PRA or the FCA may intervene at their discretion.

Lloyd’s permits its members to underwrite insurance risks through Lloyd’s syndicates. Members of Lloyd’s may participate in a syndicate for one or more underwriting year(s) by providing capital to support the syndicate’s underwriting. All syndicates are managed by Lloyd’s approved managing agents. Managing agents receive fees and profit commissions in respect of the underwriting and administrative services they provide to the syndicates.

#### General

The operations of ASML, Ark’s wholly-owned Lloyd’s managing agent, are subject to oversight by Lloyd’s, through the Lloyd’s Council. ASML’s business plan for the Syndicates, including maximum stamp capacity, requires annual approval from Lloyd’s. Stamp capacity is a measure of the amount of net premium (premiums written less acquisition costs) that a syndicate is authorized by Lloyd’s to write. Lloyd’s may require changes to any business plan presented to it or additional capital to be provided to support the underwriting plan. Lloyd’s approved stamp capacity in 2026 for Syndicate 4020, including ACSN 3832, is £850 million ($1,148 million based upon the foreign currency exchange spot rate as of December 31, 2025) and for Syndicate 3902 is £250 million ($338 million based upon the foreign currency exchange spot rate as of December 31, 2025). The Syndicates are supported by capital provided through ACML, Ark’s wholly-owned Lloyd’s corporate member.

Ark has deposited certain assets with Lloyd’s to support ACML’s underwriting business at Lloyd’s. Dividends from a Lloyd’s managing agent or a member of Lloyd’s can be declared and paid provided the relevant syndicate has sufficient profits available for distribution subject to Lloyd’s solvency requirements. By entering into a membership agreement with Lloyd’s, ACML has undertaken to comply with all Lloyd’s bye-laws and regulations as well as the provisions of the Lloyd’s Acts and the Financial Services and Markets Act 2000, as amended by the Financial Services Act 2012.

#### Capital Requirements

The underwriting capacity of a member of Lloyd’s must be supported by a deposit in the form of cash, securities or letters of credit in an amount determined under the capital adequacy regime of the U.K.’s PRA. The amount of such deposit is calculated for each member through the completion of an annual capital adequacy exercise. Under these requirements, Lloyd’s must demonstrate that each member has sufficient assets to meet its underwriting liabilities plus a required solvency margin. The required amount of Funds at Lloyd’s is determined by Lloyd’s based on each syndicate’s solvency and capital requirement as calculated through its internal model.

#### Intervention Powers

The Lloyd’s Council has wide discretionary powers to regulate members’ underwriting at Lloyd’s. It may, for instance, withdraw a member’s permission to underwrite business or to underwrite a particular class of business. The Lloyd’s Council may change the basis on which syndicate expenses are allocated or vary the Funds at Lloyd’s requirements or the investment criteria applicable to the provision of Funds at Lloyd’s. Exercising any of these powers might affect the return on the member’s participation in a given underwriting year. If a member of Lloyd’s is unable to pay its debts to policyholders, the member may obtain financial assistance from the Lloyd’s Central Fund, which in many respects acts as an equivalent to a state guaranty fund in the United States. If Lloyd’s determines that the Central Fund needs to be increased, it has the power to assess premium levies on current members of Lloyd’s. The Lloyd’s Council has discretion to call or assess up to 3% of a member’s underwriting capacity in any one year as a Central Fund contribution.

While not currently material to Ark’s operations, the Syndicates also access insurance business from the European Economic Area through the London Branch of Lloyd’s Insurance Company. Lloyd’s Insurance Company is authorized and regulated by the National Bank of Belgium and regulated by the Financial Services and Markets Authority.

### U.K. Domestic Prudential Regime

Following the United Kingdom’s exit from the European Union, U.K.-authorized insurers are subject to the U.K.’s domestic prudential regime administered by the PRA. The regime, which evolved from the EU Solvency II framework, establishes risk-based capital and governance requirements. Lloyd’s must satisfy PRA solvency requirements based on its internal model, and Ark’s underwriting capacity at Lloyd’s is subject to these PRA and Lloyd’s capital standards.

### Cybersecurity

Ark is subject to U.K. data protection laws, including the U.K. General Data Protection Regulation and the Data Protection Act 2018, and, where applicable, the EU General Data Protection Regulation. These laws impose requirements relating to the processing of personal data, including breach notification, data subject rights, governance controls and restrictions on cross-border data transfers. Violations may result in significant administrative fines and other regulatory action.

### Climate Change

In response to PRA climate change risk management guidelines, Ark has established a climate change working group and has undertaken a climate change risk assessment. The risk assessment highlighted regulatory, claims, underwriting and investment risks associated with climate change. Ark regularly analyzes climate change risk as part of its risk management framework. Ark also engages with industry peers through the Lloyd’s Climate Change market group. Ark has assigned its Chief Risk Officer responsibility under the PRA Senior Insurance Managers Regime for climate change risk. The Chief Risk Officer reports to the Ark Board on climate change matters.

### General

### Change of Control

The jurisdictions in which White Mountains operates have laws and regulations that require regulatory approval of a change of control. Where such laws apply, there can be no effective change in our control (or in the control of some or our subsidiaries) unless the person seeking to acquire control has filed a statement with the regulators and obtained prior approval for the proposed change.

### RATINGS

Insurance companies are evaluated by various rating agencies in order to measure each company’s financial strength. Higher ratings generally indicate stronger financial stability and claims paying ability. White Mountains believes that strong ratings are important factors in the marketing and sale of insurance products and services to agents, consumers and ceding companies.

As of February 27, 2026, each of Lloyd’s Syndicates 4020 and 3902 benefits from the financial strength rating of “A+/stable” by A.M. Best Company, Inc. (“A.M. Best”) and “AA-/stable” by Standard & Poor’s assigned to the Lloyd’s marketplace. “A+” is the second highest of 16 financial strength ratings assigned by A.M. Best and “AA-” is the fourth highest of 23 financial strength ratings assigned by Standard & Poor’s.

As of February 27, 2026, GAIL’s financial strength rating was “A/stable” by A.M. Best. “A” is the third highest of 16 financial strength ratings assigned by A.M. Best.

### HUMAN CAPITAL

As of December 31, 2025, White Mountains employed 1,648 people (consisting of 85 people at the Company, WM Capital, its other intermediate holding companies, WM Advisors, WTM Partners and HG Global, 300 people at Ark, 17 people at Kudu, 288 people at Distinguished and 958 people at its consolidated Other Operating Businesses).

White Mountains’s strength lies in its people, and it proactively supports each employee’s well-being and development. The Company’s Board of Directors receives periodic reporting on employee satisfaction and concerns and interacts with employees across White Mountains. White Mountains has an inclusive, team-oriented culture in which all employees are treated with respect. Under the guidelines of the Company’s Code of Business Conduct, it is firmly committed to providing equal employment opportunities. White Mountains values diversity of backgrounds, experiences and ideas, which it believes fosters more engaging discussions, stronger collaboration and better company performance. White Mountains invests in the professional development of its workforce and is committed to the long-term development of its workforce and the cultivation of its next generation of leaders.

## Risk factors

As filed, 60,168 characters.

The information contained in this report may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. *See “***FORWARD-LOOKING STATEMENTS”** *on page 101 for specific important factors that could cause actual results to differ materially from those contained in forward-looking statements.* The Company’s actual future results and trends may differ materially depending on a variety of factors including, but not limited to, the risks and uncertainties discussed below.

### Risks Related to White Mountains

***We have successfully created shareholder value through acquisitions and dispositions. We may not be able to continue to create shareholder value through such transactions in the future, which could materially adversely affect our results of operations and financial condition.***

In past years, we have completed numerous acquisitions and dispositions, many of which have contributed significantly to creating shareholder value. Failure to identify and complete future acquisitions and dispositions could limit our ability to create shareholder value. Even if we were to identify and complete future acquisitions and dispositions, there is no assurance that such transactions will ultimately achieve their anticipated benefits, and such transactions could materially adversely affect our results of operations and financial condition.

***If we are required to write down goodwill and other intangible assets, it could materially adversely affect our results of operations and financial condition.***

As of December 31, 2025, we had total goodwill and other intangible assets of $1,020 million on our consolidated balance sheet, of which $578 million relates to Distinguished and $293 million relates to Ark.

We periodically review goodwill and other intangible assets to determine whether an impairment has occurred. An impairment of goodwill or other intangible assets occurs when the carrying value of the asset exceeds its fair value. The evaluation of goodwill or other intangible assets for impairment requires the use of significant judgment in determining fair value, including assumptions about the future performance of the associated business. Our consolidated operating companies may experience unexpected circumstances that cause future performance to differ significantly from those assumptions, which could cause us to conclude that goodwill and other intangible assets are impaired. Such an impairment would result in a non-cash charge to income that could materially adversely affect our results of operations and financial condition.

### Risks Related to Ark/WM Outrigger’s Business and Industry

***Unpredictable catastrophic events could materially adversely affect our results of operations and financial condition.***

Ark underwrites insurance and reinsurance policies that cover unpredictable catastrophic events all over the world. Ark has exposure to losses caused by natural disasters and other events such as hurricanes, windstorms, earthquakes, floods, wildfires, tornadoes, tsunamis and severe weather. Catastrophes can also include large losses driven by public health crises, terrorist attacks, war and war-like actions, explosions, infrastructure failures and cyber attacks.

The extent of a catastrophe loss is a function of both the severity of the event and the total amount of insured exposure to the event, as well as the coverage provided to customers. Increases in the value and concentration of insured property or insured employees, the effects of inflation, changes in weather patterns and increased terrorism and war and war-like actions could increase the future frequency and/or severity of claims from catastrophic events. Climate change, which is characterized by higher temperatures, sea level rise and more extreme weather events including droughts, heavy storms, wildfires and stronger hurricanes, increases the frequency and severity of certain major natural catastrophes. There is also a growing threat of cyber risks due to the increasing interconnectivity of global systems. Claims from catastrophic events could materially adversely affect our results of operations and financial condition. In addition, following a large loss event, Ark could have diminished capacity to write new insurance and reinsurance policies due to reductions in its capital levels.

Ark seeks to manage its exposure to catastrophic losses by limiting and monitoring the aggregate insured value of policies in geographic areas with exposure to catastrophic events and by buying reinsurance. To manage, monitor and analyze insured values and potential losses, Ark utilizes proprietary and third-party catastrophe management software to estimate potential losses for many different catastrophe scenarios. Ark incorporates the physical risk of climate change in its underwriting process through sensitivity and stress testing of its catastrophe models, including increased frequency of U.S. windstorms and the implications of storm surge. Ark’s estimates of potential losses are dependent on many variables, including assumptions about storm intensity, storm surge, loss amplification, loss adjustment expenses and insurance-to-value in the aftermath of weather-related catastrophes. In addition, Ark has to account for quality of data provided by insureds. Accordingly, if the assumptions are incorrect, the actual losses Ark might incur from a catastrophe could be materially different than the expectation of losses generated from modeled catastrophe scenarios, which could materially adversely affect our results of operations and financial condition.

***Ark and its subsidiaries benefit from favorable financial strength ratings from A.M. Best, Standard & Poor’s and others, the deterioration of which could materially adversely affect its ability to conduct business and, consequently, could materially adversely affect our results of operations and financial condition.***

Third-party rating agencies assess and rate the financial strength, including claims-paying ability, of insurers, reinsurers and the Lloyd’s marketplace. These ratings are based upon criteria established by the rating agencies and are subject to revision at any time at the sole discretion of the agencies. Some of the criteria relate to general economic conditions and other circumstances outside the rated company’s control. These financial strength ratings are used by policyholders, agents and brokers to assess the suitability of insurers and reinsurers as business counterparties and are an important factor in establishing the competitive position of insurance and reinsurance companies. Rating agencies periodically evaluate Ark to confirm that it continues to meet the criteria of the rating previously assigned to it.

The maintenance of an “A-” or better financial strength rating is particularly important to Ark’s ability to write property and casualty insurance and reinsurance business in most markets. Ark writes insurance and reinsurance through Lloyd’s Syndicates 4020 and 3902, each of which benefits from the financial strength rating of “A+/stable” by A.M. Best and “AA-/stable” by Standard & Poor’s assigned to the Lloyd’s marketplace. GAIL, Ark’s wholly-owned Bermuda-based insurance and reinsurance company, has an “A/stable” financial strength rating by A.M. Best. See “**RATINGS”** on page 28.

A downgrade, withdrawal or negative watch/outlook of these financial strength ratings could severely limit or prevent Ark from writing new policies or renewing existing policies, which could materially adversely affect our results of operations and financial condition. A downgrade, withdrawal or negative watch/outlook of these financial strength ratings also could limit Ark’s ability to raise new debt or could cause new and certain existing debt to be costlier and/or have more restrictive conditions.

***Ark may not adequately alleviate risk through reinsurance and retrocessional arrangements, which could materially adversely affect our results of operations and financial condition.***

Ark attempts to limit its risk of loss through reinsurance and retrocessional arrangements. Retrocessional arrangements refer to reinsurance purchased by a reinsurer to cover its own risks assumed from ceding companies. The availability and cost of reinsurance and retrocessional protection is subject to market conditions, which are outside of Ark’s control. In addition, the coverage provided by Ark’s reinsurance and retrocessional arrangements may not cover certain of its future liabilities. As a result, Ark may not be able to adequately alleviate risk through these arrangements, which could materially adversely affect our results of operations and financial condition.

In addition, due to various factors, including the price or availability of reinsurance or retrocessional coverage, Ark may decide to increase the amount of risk retained by purchasing less reinsurance. Such a determination has the effect of increasing Ark’s financial exposure to losses associated with risks that it underwrites and, in the event of significant losses associated with a given risk, could materially adversely affect our results of operations and financial condition.

Purchasing reinsurance does not relieve Ark of its underlying obligations to policyholders or ceding companies. As a result, any inability to collect amounts due from reinsurers could materially adversely affect our results of operations and financial condition. The inability to collect amounts due from reinsurers, including Outrigger Re Ltd., can result from a number of scenarios, including: (i) reinsurers withholding payment due to a dispute, including coverage terms, adverse judicial rulings or failed arbitration, or other factors beyond Ark’s control; (ii) reinsurers becoming unable to pay amounts owed to Ark as a result of a deterioration in their financial condition; and (iii) in the case of Outrigger Re Ltd., losses exceeding amounts within the collateral trust accounts. While we currently believe the condition of Ark’s reinsurers is strong, it is possible that one or more of Ark’s reinsurers will be adversely affected by future significant losses or economic events causing them to be unable or unwilling to pay amounts owed.

***The property and casualty insurance and reinsurance industries are highly competitive and cyclical, and Ark may not be able to compete effectively in the future, which could materially adversely affect our results of operations and financial condition.***

The property and casualty insurance and reinsurance industries are highly competitive and have historically been cyclical, experiencing periods of severe price competition and less selective underwriting standards (soft markets) followed by periods of relatively high prices and more selective underwriting standards (hard markets). Ark competes with other Lloyd’s syndicates, London market participants and major U.S., Bermuda, European and other international insurance and reinsurance companies. Many of these competitors have greater financial resources, have more established long-term and continuing business relationships throughout the insurance and reinsurance industries and may have higher financial strength ratings, which can represent significant competitive advantages for them.

Soft primary insurance market conditions could lead to a significant reduction in reinsurance premium rates, less favorable contract terms and fewer submissions for Ark’s reinsurance underwriting capacity. The supply of reinsurance is also related to the level of reinsured losses and the level of industry capital which, in turn, may fluctuate in response to changes in rates of return earned in the reinsurance industry. As a result, the reinsurance industry historically has been cyclical, characterized by periods of intense price competition due to excess underwriting capacity, as well as periods when shortages of capacity permitted improvements in reinsurance rate levels and terms and conditions. In addition, the ease of entry into the reinsurance sector facilitates competition from third-party capital in the property catastrophe excess reinsurance line. This alternative capital provides collateralized property catastrophe protection in the form of catastrophe bonds, industry loss warranties, sidecars and other vehicles that facilitate the ability for non-reinsurance entities, such as hedge funds and pension funds, to compete for property catastrophe excess reinsurance business outside of the traditional treaty market.

We expect to continue to experience the effects of the insurance and reinsurance industries’ cyclicality. If Ark is unable to maintain its competitive position throughout soft and hard market cycles, its business may be adversely affected, and it may not be able to compete effectively in the future, which could materially adversely affect our results of operations and financial condition.

***Ark’s loss and LAE reserves may be inadequate to cover the ultimate liability for losses, which could materially adversely affect our results of operations and financial condition.***

Ark maintains reserves to cover its estimated ultimate liabilities for loss and LAE. Loss and LAE reserves are typically comprised of (i) case reserves for reported claims and (ii) incurred but not reported (“IBNR”) reserves for losses that have occurred but for which claims have not yet been reported and for expected future development on case reserves. Loss and LAE reserves are estimates of what Ark believes the settlement and administration of claims will cost based on facts and circumstances then known. These estimates involve actuarial and claims assessments and require Ark to make a number of assumptions about future events that are subject to unexpected changes and are beyond Ark’s control, such as future trends in claim severity, emerging coverage issues, frequency, inflation, legislative and judicial changes, regulatory changes, adverse court rulings and other factors. Because of uncertainties associated with estimating ultimate loss and LAE reserves, we cannot be certain that Ark’s reserves are adequate. In the event that Ark’s reserves are insufficient to cover the actual loss and LAE, Ark may need to add to the reserves, which could materially adversely affect our results of operations and financial condition. For further discussion of our loss and LAE reserves, see “**CRITICAL ACCOUNTING ESTIMATES — Loss and LAE Reserves”** on page 90.

### Risks Related to HG Global’s Business and Industry

***HG Re is only licensed to provide reinsurance to BAM. If BAM does not maintain its favorable financial strength rating from Standard & Poor’s, it could materially adversely affect HG Re’s business and, consequently, could materially adversely affect our results of operations and financial condition.***

HG Re is only licensed to provide reinsurance to BAM. Accordingly, HG Re, through its reinsurance treaties with BAM, is dependent on BAM’s ability to write municipal bond insurance policies. The maintenance of an “AA” or better financial strength rating from Standard & Poor’s is particularly important to BAM’s ability to conduct its business.

Third-party rating agencies assess and rate the financial strength of insurers, including claims-paying ability. These ratings are based upon criteria established by the rating agencies and are subject to revision at any time at the sole discretion of the rating agencies. Some of the criteria relate to general economic conditions and other circumstances outside the rated insurer’s control. The financial strength rating of Standard & Poor’s is used by outside parties to assess the suitability of BAM as a business counterparty and is an important factor in establishing BAM’s competitive position.

Standard & Poor’s periodically evaluates BAM to confirm that it continues to meet the criteria of the rating previously assigned to it. On June 6, 2017, Standard & Poor’s placed BAM on credit watch negative and initiated a detailed review of BAM’s financial strength rating. On June 26, 2017, Standard & Poor’s concluded its review and affirmed BAM’s “AA/stable” financial strength rating. During the time that BAM’s financial strength rating was placed on credit watch negative by Standard & Poor’s, it voluntarily withdrew from the marketplace and did not write any municipal bond insurance policies.

On July 11, 2025, Standard & Poor’s concluded its most recent review and affirmed BAM’s “AA/stable” financial strength rating. A downgrade, withdrawal or negative watch/outlook of BAM’s financial strength rating could severely limit or prevent BAM’s ability to write municipal bond insurance policies, which could materially adversely affect HG Re’s business, and, consequently, could materially adversely affect our results of operations and financial condition.

***Certain sectors of the municipal bond insurance industry are highly competitive, and BAM may not be able to compete effectively in the future, which could materially adversely affect HG Re’s business and, consequently, could materially adversely affect our results of operations and financial condition.***

Certain sectors of the municipal bond insurance industry are highly competitive. HG Re is only licensed to provide reinsurance to BAM. Accordingly, HG Re, through its reinsurance treaties with BAM, is indirectly exposed to this competition. BAM’s primary competitor is Assured, which also provides financial guarantees on non-municipal debt, including structured finance. BAM and Assured each seek to differentiate themselves through risk selection, financial strength ratings, claims paying resources and underwriting strategies. If BAM is unable to compete effectively against Assured, it could result in fewer policies issued, lower premium levels and less favorable policy terms and conditions, which could materially adversely affect HG Re’s business, and, consequently, could materially adversely affect our results of operations and financial condition.

***We are exposed to losses from municipal bond insurance written by BAM through our reinsurance treaties between HG Re and BAM, which could materially adversely affect our results of operations and financial condition.***

Our reinsurance subsidiary, HG Re, provides (i) first-loss reinsurance protection of up to 15%-of-par outstanding for each policy assumed from BAM and (ii) last-dollar protection for exposures on municipal bonds insured by BAM in excess of the NYDFS single issuer limits. Should the policies assumed from BAM experience insured losses for any reason, this could materially adversely affect our results of operations and financial condition.

***If BAM does not pay some or all of the principal and interest due on the BAM Surplus Notes, it could materially adversely affect our results of operations and financial condition.***

As of December 31, 2025, White Mountains owned BAM Surplus Notes with a principal balance of $277 million and accrued interest receivable of $214 million, both at nominal value. The BAM Surplus Notes were carried at a fair value of $339 million as of December 31, 2025. No payment of principal or interest on the BAM Surplus Notes may be made without the approval of the NYDFS. Under its agreements with HG Global, BAM is required to seek regulatory approval to pay principal and interest on the BAM Surplus Notes only to the extent that its capital resources continue to support its outstanding obligations, business plan and rating. It is unlikely that BAM would pay principal and interest on the BAM Surplus Notes if such payments could lead to a rating downgrade. In 2025, the NYDFS approved cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. We cannot guarantee that the NYDFS will approve payments on the BAM Surplus Notes in the future.

BAM’s ability to repay principal and interest on the BAM Surplus Notes is dependent on a number of factors, many of which are beyond BAM’s control, including primary municipal bond issuance levels, insured penetration rates, interest rate levels, credit spreads, trading value, capture rate and market share. BAM also could incur significant losses from the municipal bonds it insures. If BAM does not repay some or all of the principal and interest on the BAM Surplus Notes, it could materially adversely affect our results of operations and financial condition.

***We may be subject to volatility from the valuation of the BAM Surplus Notes, which could materially adversely affect our results of operations and financial condition.***

As of December 31, 2025, the fair value of the BAM Surplus Notes was $339 million using a discounted cash flow analysis. White Mountains’s reported book value per share may be subject to volatility in the future, as the valuation of the BAM Surplus Notes under the discounted cash flow analysis could be volatile. For example, in 2025 White Mountains recognized a decrease of $38 million in the fair value of the BAM Surplus Notes. We use judgment in selecting the key inputs to the discounted cash flow analysis. With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. See “**BAM Surplus Notes”** under “**CRITICAL ACCOUNTING ESTIMATES — Fair Value Measurements”** on page 88 for a description of the methodology and key inputs we use to determine the valuation of the BAM Surplus Notes. Given the inherent subjectivity and uncertainty in the methodology and inputs used to determine the fair value of the BAM Surplus Notes, the value established using this methodology may not be fully realized. Should there be a significant decrease in the valuation of the BAM Surplus Notes, it could materially adversely affect our results of operations and financial condition.

***The municipal bond industry is highly regulated at the federal and state level, and certain municipal bonds enjoy preferential tax treatment. Significant changes to these regulations or to the tax treatment of municipal bonds could materially adversely affect BAM’s and HG Re’s business and, consequently, could materially adversely affect our results of operations and financial condition.***

The municipal bond market is subject to regulations at both the federal and state level, and certain municipal bonds enjoy preferential tax treatment. Changes to such regulations or to the tax treatment of municipal bonds could affect the issuance of certain municipal bonds or could reduce the attractiveness of and market for BAM’s financial guarantee solutions. This could decrease the amount of bond insurance issued by BAM and thereby reduce payments on the BAM Surplus Notes and risk premiums ceded to HG Re, both of which could materially adversely affect our results of operations and financial condition.

### Risks Related to Kudu’s Business and Industry

***Kudu’s financial performance is dependent upon its clients’ asset and performance-based fees, which are subject to a variety of economic, market and other risks. Additionally, Kudu’s managers participate in a highly competitive, highly regulated industry. Kudu’s managers may not be able to compete effectively in the future, which could materially adversely affect our results of operations and financial condition.***

Kudu provides capital solutions for asset and wealth management firms through Participation Contracts. Kudu’s managers generate their revenues and earnings by charging asset-based fees, which are typically a percentage of the value of the assets they manage for their clients, and/or performance-based fees, which are typically a portion of actual returns achieved for their clients above a target return. Much of the revenue that Kudu generates from its clients is subject to the same general economic and market risks that may affect our investment portfolio. See ***Risk Factors, “Our investment portfolio may suffer reduced returns or losses, which could materially adversely affect our results of operations and financial condition. Adverse changes in equity markets, interest rates, debt markets or foreign currency exchange rates could result in significant losses to the value of our investment portfolio.”*** on page 35.

Additionally, Kudu’s managers participate in a highly competitive, highly regulated industry that subjects their operations to a number of other risks that are out of our control, including (i) changes in investor preference from the actively-managed investments offered by Kudu’s managers to passively-managed investments; (ii) the ability of Kudu’s managers to successfully attract new clients and retain existing ones; (iii) the ability of Kudu’s managers to avoid fee compression; (iv) the reliance of Kudu’s managers on a small number of key personnel; and (v) future changes to regulations that make Kudu’s managers’ businesses more cumbersome and expensive to operate. If Kudu’s managers are unable to compete effectively in the future, Kudu’s business may be materially adversely affected, which could materially adversely affect our results of operations and financial condition.

### Risks Related to Distinguished’s Business and Industry

***Distinguished’s commission revenues are dependent on many factors, some of which are beyond its control, including the pricing and profitability of certain segments of the property and casualty insurance industry, which is highly competitive and cyclical. Distinguished may not be able to compete effectively in the future, which could materially adversely affect our results of operations and financial condition.***

Distinguished generates most of its revenues from commissions that are a portion of premiums charged by insurance companies to their insureds. Distinguished is an MGA and program administrator with delegated binding authorities, and as such, its carrier partners bear the insurance risk on the programs designed and underwritten by Distinguished. Should Distinguished fail to meet the profitability expectations of the carriers that underwrite the business it places, those carriers could choose to stop underwriting the business or reduce the commission rate they will pay for placement services, which could materially adversely affect Distinguished’s commission revenues and, consequently, could materially adversely affect our results of operations and financial condition.

Distinguished’s future commission revenues could also be materially adversely affected by other factors beyond its control, including (i) the increasing availability of capital markets-based products designed to replace traditional insurance and reinsurance products; (ii) growth in the direct-to-consumer sales channel at the expense of insurance intermediaries including agents and brokers; (iii) the percentage of premium insurance carriers will pay for placement services; (iv) the availability and cost of reinsurance; and (v) future trends in claim severity, emerging coverage issues, frequency, inflation, legislative and judicial changes, regulatory changes, adverse court rulings and other factors.

The property and casualty insurance industry is highly competitive and has historically been cyclical, experiencing periods of severe price competition and less selective underwriting standards (soft markets) followed by periods of relatively high prices and more selective underwriting standards (hard markets). The cyclicality of the property and casualty markets is beyond Distinguished’s control and could materially adversely affect our results of operations and financial condition by reducing the commissions it receives for property and casualty insurance placed during soft markets. We expect to continue to experience the effects of cyclicality. If Distinguished is unable to successfully manage the risks associated with soft markets, Distinguished’s business may be materially adversely affected, which could materially adversely affect our results of operations and financial condition.

***A substantial portion of Distinguished’s business is placed with one insurance carrier, and most of Distinguished’s business is placed with a small number of carriers. Any deterioration in the arrangements with its carriers could adversely affect Distinguished’s business, which could materially adversely affect our results of operations and financial condition.***

Distinguished placed approximately 22% of its business with its single largest carrier during the year ended December 31, 2025. Distinguished placed approximately 61% of its business with its three largest carriers during the year ended December 31, 2025. Should any of these carriers reduce the volume of business accepted from Distinguished or adversely change the terms and conditions of placement, we cannot guarantee that Distinguished would be able to find other carriers to assume the business, which could materially adversely affect our results of operations and financial condition.

***Distinguished primarily relies on third-party agents and brokers to distribute its products, and any deterioration in the relationships with these parties could adversely affect Distinguished’s business, which could materially adversely affect our results of operations and financial condition.***

Substantially all of Distinguished’s products are distributed through third-party agents and brokers who have the principal relationships with policyholders. Agents and brokers have significant influence over renewals, and thus Distinguished’s business model is dependent on its relationships with, and the success of, the agents and brokers with whom Distinguished does business.

Because Distinguished primarily relies on third-party agents and brokers as its sales channel, any deterioration in the relationships with these parties or failure to provide competitive compensation could lead them to place less premium with Distinguished. Distinguished places a substantial portion of its premium through a limited number of agents and broker relationships. For the year ended December 31, 2025, the top three relationships accounted for 10% of Distinguished’s managed premiums. Loss of all or a substantial portion of the business provided by one or more of these agents and brokers could materially adversely affect Distinguished’s business, which could materially adversely affect our results of operations and financial condition.

### Risks Related to Investments

***Our investment portfolio may suffer reduced returns or losses, which could materially adversely affect our results of operations and financial condition. Adverse changes in equity markets, interest rates, debt markets or foreign currency exchange rates could result in significant losses to the value of our investment portfolio.***

Our investment portfolio primarily consists of fixed maturity investments, short-term investments, common equity securities, our investment in MediaAlpha and other long-term investments. Other long-term investments consist primarily of Kudu’s Participation Contracts, the Bamboo SPV, PassportCard/DavidShield, the BroadStreet SPV, private equity funds and hedge funds, a bank loan fund and Lloyd’s trust deposits. We invest to maximize long-term after-tax total returns while taking prudent levels of risk and maintaining a diversified portfolio subject to our investment guidelines and various regulatory restrictions. However, investing entails substantial risks. We may not achieve our investment objectives, and our investment performance may vary substantially over time. Losses or volatility in the equity or fixed income markets could materially adversely affect our results of operations and financial condition.

The fair market value of our investment portfolio is affected by general economic and market conditions that are outside of our control, including (i) fluctuations in equity market levels, interest rates, debt market levels and foreign currency exchange rates; (ii) public health crises, natural disasters, terrorist attacks, war and war-like actions and other outside events; and (iii) credit losses sustained by issuers. A significant decline in the equity markets such as that experienced from September 2008 to March 2009 could materially adversely affect our results of operations and financial condition. In addition to causing declines in the fair value of securities that we own in our investment portfolio, public health crises, natural disasters, terrorist attacks and other outside events can adversely affect general commercial activity and the economies of many countries, which could materially adversely affect the business, financial condition and results of operations of the entities in which we have invested. For example, reductions of leisure travel, due to (i) travel restrictions imposed by governments due to the COVID-19 pandemic and (ii) fewer international flights in and out of Israel as a result of the regional conflict in the Middle East negatively impacted revenues at PassportCard/DavidShield. We are also exposed to changes in debt markets. Interest rates are highly sensitive to many factors, including governmental monetary policies, economic and political conditions and other factors beyond our control. In particular, a significant increase in interest rates, as experienced in 2022, could result in significant losses in the fair value of our investment portfolio. A significant increase in interest rates that causes severe losses could materially adversely affect our results of operations and financial condition.

In addition, certain of our other long-term investments are not regularly traded in active investment markets and may be illiquid. These investments can experience volatility in their returns or valuations, which could materially adversely affect our results of operations and financial condition.

***We may be subject to volatility from our investment in MediaAlpha, which could materially adversely affect our results of operations and financial condition.***

White Mountains’s investment in MediaAlpha is valued based on the publicly-traded share price of MediaAlpha’s common stock, which at the December 31, 2025 closing price of $12.95 per share was $231 million. As a result, White Mountains’s reported book value per share may be subject to future volatility, as the valuation of its investment in MediaAlpha is based on the publicly-traded share price of MediaAlpha’s common stock. Should there be a significant decrease in the publicly-traded share price of MediaAlpha’s common stock, it could materially adversely affect our results of operations and financial condition.

***Our investment portfolio includes securities that do not have readily observable market prices. We use valuation methodologies that are inherently subjective and uncertain to value these securities. The values of securities established using these methodologies may never be realized, which could materially adversely affect our results of operations and financial condition.***

As of December 31, 2025, White Mountains owned $1,814 million in securities, including Kudu’s Participation Contracts, the Bamboo SPV and PassportCard/DavidShield, that are not actively traded in public markets, do not have readily observable market prices and are classified as Level 3 investments in the GAAP fair value hierarchy. On a quarterly basis, we make a good faith determination of the fair value of our Level 3 investments in our GAAP financial statements using valuation techniques that are inherently subjective and uncertain.

In determining the GAAP fair value of these securities, we use judgment in selecting the fair value methodology and the significant inputs that are employed by that methodology for each such investment. See “**CRITICAL ACCOUNTING ESTIMATES — Fair Value Measurements”** on page 87 for a description of the methodologies we use to determine the GAAP fair value of our investments without a readily observable market price. Given the inherent subjectivity and uncertainty in the methodologies we use to determine the fair value of our investments without a readily observable market price, the values of such investments established using these methodologies may never be realized, which could materially adversely affect our results of operations and financial condition.

### Risks Related to Taxation

***We may not meet the requirements of the five-year deferral from the Bermuda corporate income tax or the OECD Pillar Two Undertaxed Profits Rule, which could materially adversely affect our results of operations and financial condition.***

On December 27, 2023, Bermuda enacted a 15% corporate income tax that became effective on January 1, 2025. The Bermuda legislation defers the effective date for five years for Bermuda companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries, (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets and (iii) not have a consolidated Bermuda affiliate or Bermuda permanent establishment directly or indirectly owned by a parent entity that is subject to the Income Inclusion Rule of Pillar Two in any jurisdiction. White Mountains expects to meet the requirements to be exempt from the Bermuda corporate income tax until January 1, 2030.

On December 15, 2022, European Union Member States voted to adopt the European Union Minimum Tax Directive (the “EU Minimum Tax Directive”) in conformity with the Organization for Economic Cooperation and Development (“OECD”) Pillar Two initiative. The Pillar Two initiative includes a set of model rules that are generally designed to impose a top-up tax on a large multinational enterprise group to the extent that the group is not subject to an effective tax rate of at least 15% in each jurisdiction in which the group has a consolidated affiliate or permanent establishment. The EU Minimum Tax Directive required European Union Member States to enact conforming law by December 31, 2023. The main rule of the EU Minimum Tax Directive, the Income Inclusion Rule (“IIR”), was to become effective for fiscal years beginning on or after December 31, 2023, while the Undertaxed Profits Rule (“UTPR”) was to become effective for fiscal years beginning on or after December 31, 2024. The EU Minimum Tax Directive also permits European Union Member States to elect to apply a Qualified Domestic Minimum Top-up Tax (“QDMTT”) for fiscal years beginning on or after December 31, 2023.

On July 11, 2023, the United Kingdom enacted conforming Pillar Two legislation including the IIR and QDMTT. On March 20, 2025, the United Kingdom enacted legislation adopting the Pillar Two UTPR. Under the legislation, the effective date of the UTPR is deferred for five years to fiscal years beginning on or after December 31, 2029 for U.K. companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the U.K. UTPR until January 1, 2030.

On December 20, 2023, Luxemburg enacted conforming Pillar Two legislation including the IIR, UTPR and QDMTT. The Luxembourg legislation defers the effective date of the UTPR for five years to fiscal years beginning on or after December 31, 2029 for Luxembourg companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the Luxembourg UTPR until January 1, 2030.

The failure by White Mountains to meet the requirements of the five-year deferral under the Bermuda corporate income tax or the OECD Pillar Two UTPR could materially adversely affect our results of operations and financial condition.

***We may be treated as a PFIC, in which case a U.S. holder of our common shares could be subject to disadvantageous rules under U.S. federal income tax laws.***

Significant potential adverse U.S. federal income tax consequences apply to any U.S. person who owns shares in a passive foreign investment company (“PFIC”). In general, a non-U.S. corporation is classified as a PFIC for a taxable year in which, after taking into account the income and assets of the corporation and certain subsidiaries pursuant to certain “look-through” rules, either (i) 75% or more of its gross income is passive income or (ii) 50% or more of the average quarterly value of its gross assets is attributable to assets that produce passive income or are held for the production of passive income. If a corporation is treated as a PFIC for a taxable year, it is generally treated as a PFIC for all later taxable years. Passive income for PFIC purposes generally includes interest, dividends and other investment income, subject to certain exceptions.

While we believe that White Mountains should not currently be treated as a PFIC based upon the income and assets of White Mountains and the income and assets of its subsidiaries (taking into account certain applicable subsidiary “look-through” rules), there is no assurance that White Mountains will not become a PFIC in the future as a result of changes in law or regulations (or their application to White Mountains) or changes in our assets, income or business operations. Nor is there assurance that the Internal Revenue Service will not successfully argue that White Mountains is now, or in the future may become, a PFIC.

If we are determined to be a PFIC, a U.S. person may be subject to less advantageous tax consequences upon the sale, exchange or receipt of dividends with respect to our common shares and may be required to pay U.S. federal income tax at ordinary income rates for gains and dividends, as well as an interest charge on certain “excess distributions.” Certain elections designed to mitigate the adverse consequences of owning shares in a PFIC, including a “Protective QEF Election,” may be available. If you are a U.S. person, we encourage you to consult your own tax advisor concerning the potential tax consequences to you under the PFIC rules.

***The Company and certain of our non-U.S. subsidiaries may become subject to U.S. tax, which could materially adversely affect our results of operations and financial condition.***

The Company and our non-U.S. subsidiaries without U.S. branches operate in a manner such that none of these companies should be subject to U.S. tax (other than U.S. excise tax on insurance and reinsurance premium income attributable to insuring or reinsuring U.S. risks and U.S. withholding tax on some types of U.S. source investment income) because none of these companies should be treated as engaged in a trade or business within the United States. However, because there is considerable uncertainty as to the activities that constitute being engaged in a trade or business within the United States, we cannot be certain that the Internal Revenue Service will not contend successfully that the Company or its non-U.S. subsidiaries without U.S. branches are engaged in a trade or business in the United States. If the Company or any of its non-U.S. subsidiaries without U.S. branches were considered to be engaged in a trade or business in the United States, such entity could be subject to U.S. corporate income and branch profits taxes on the portion of its earnings effectively connected to such U.S. business, which could materially adversely affect our results of operations and financial condition.

***Changes in tax laws or tax treaties could materially adversely affect our results of operations and financial condition.***

The income of our U.S. subsidiaries is subject to U.S. federal, state and local income tax and other taxes. The income of our non-U.S. subsidiaries is generally subject to a lower tax rate than that imposed by the United States. Certain of our non-U.S. subsidiaries are eligible for the benefits of tax treaties between the United States and other countries. We believe our non-U.S. subsidiaries will continue to be eligible for treaty benefits. However, it is possible that factual changes or changes to U.S. tax laws or changes to tax treaties that presently apply to our non-U.S. subsidiaries could increase income subject to tax, or the tax rate on income, in the United States. Similarly, changes to the applicable tax laws, treaties or regulations of other countries could subject the income of members of our group to higher rates of tax outside the United States. Additionally, the base erosion and profit shifting (“BEPS”) project currently being undertaken by the OECD and the European Commission’s investigation into illegal state aid may result in changes to long standing tax principles. The Bermuda corporate income tax and the Pillar Two worldwide minimum tax currently being enacted around the world are examples of the effects of the BEPS project. Such changes in tax laws or tax treaties could materially adversely affect our results of operations and financial condition.

***Our non-U.S. subsidiaries are treated as CFCs and may subject a U.S. 10% shareholder of our common shares to disadvantageous rules under U.S. federal income tax laws.***

The Tax Cuts and Jobs Act of 2017 (“TCJA”) modified certain U.S. tax rules that apply to controlled foreign corporations (“CFCs”). As a result of these changes, each of our non-U.S. subsidiaries is treated as a CFC. If any of our shareholders is a “U.S. 10% shareholder” (as described below) that directly or indirectly owns stock in White Mountains, that shareholder must include in its taxable income each year its pro rata share of our CFC subsidiaries’ “subpart F income” and global intangible low-taxed income (“GILTI”) for that year, even if no distributions are received by the U.S. 10% shareholder.

Due to changes made by the TCJA, a shareholder is treated as a U.S. 10% shareholder if the shareholder is a U.S. person who owns directly, indirectly or through constructive ownership rules 10% or more of either the voting power or the total value of our shares. As a result, a U.S. person that owns (directly, indirectly or through constructive ownership rules) 10% or more of our shares will generally be treated as a U.S. 10% shareholder of our CFC subsidiaries, notwithstanding the voting power restrictions of our shares. However, a person that is a U.S. 10% shareholder solely as a result of constructive ownership rules (i.e., such person does not directly or indirectly own stock of White Mountains) should not have a subpart F income inclusion or GILTI inclusion with respect to our CFC subsidiaries.

On July 4, 2025, the U.S. enacted the One Big Beautiful Bill Act (“OBBBA”). The OBBBA reinstated the pre-TCJA rules for determining status as a U.S. 10% shareholder and made certain changes to the subpart F and GILTI rules (including renaming GILTI “net CFC tested income”), effective for tax years beginning after December 31, 2025.

The OBBBA enacted a separate inclusion regime for a “foreign controlled U.S.” (“FCUS”) shareholder of a “foreign controlled foreign corporation” (“FCFC”). A FCUS shareholder of a FCFC must include in its taxable income each year its pro rata share of a FCFC’s subpart F income and CFC tested income for that year, even if no distributions are received by the FCUS shareholder. A FCUS shareholder is a U.S. person who owns more than 50% of a foreign corporation directly, indirectly or through certain constructive ownership rules. A FCFC is a foreign corporation (other than a CFC) where FCUS shareholders own more than 50% of the stock of the foreign corporation directly, indirectly or through certain constructive ownership rules. The enacted provisions apply to tax years of foreign corporations beginning after December 31, 2025.

If you are a U.S. person who might be a U.S. 10% shareholder or a FCUS shareholder, we encourage you to consult your own tax advisor concerning these rules.

***Proposed regulations could subject U.S. persons who are shareholders to disadvantageous rules under U.S. federal income tax laws pertaining to “related person insurance income.”***

Proposed regulations issued on January 24, 2022 address the subpart F “related person insurance income” (“RPII”) tax regime. The proposed regulations would expand the scope of relationships giving rise to RPII by treating intra-group reinsurance transactions as generating RPII if a non-U.S. parent entity of the group is majority owned by U.S. persons. If the proposed regulations are finalized as written, U.S. shareholders of the Company could be required to include in their taxable income a proportionate share of White Mountains’s RPII annually as subpart F income, even if no distributions are received by the U.S. shareholder.

The proposed regulations generally would apply to tax years of corporations beginning on or after the date on which finalized regulations are published in the Federal Register and to tax years of U.S. persons in which or with which those corporations' tax years end. We encourage shareholders who are U.S. persons to consult their own tax advisors concerning the proposed regulations.

### Risks Related to Laws and Regulation

***Regulation may have a material adverse effect on our operations and financial condition.***

We are subject to supervision and regulation by regulatory authorities in the various jurisdictions in which we conduct business, including state and national insurance regulators. Regulatory authorities have broad regulatory, supervisory and administrative powers relating to, among other things, data protection and data privacy, solvency standards, licensing, coverage requirements, policy rates and forms and the form and content of financial reports. Regulatory authorities continue to implement new or enhanced regulatory requirements. Regulatory authorities also may seek to exercise their supervisory or enforcement authority in new or more extensive ways. These actions, if they occur, could affect the competitive market and the way in which we conduct our business and manage our capital and could result in lower revenues and higher costs. As a result, such actions could materially adversely affect our results of operations and financial condition.

***Bermuda law differs from the laws in effect in the United States and may afford less protection to shareholders.***

We are organized under the laws of Bermuda, and a significant portion of our assets are located outside the United States. As a result, it may not be possible for our shareholders to enforce court judgments obtained in the United States against us based on the civil liability provisions of the federal or state securities laws of the United States, either in Bermuda or in countries other than the United States where we have assets. In addition, there is some doubt as to whether the courts of Bermuda and other countries would recognize or enforce judgments of U.S. courts obtained against us or our directors or officers based on the civil liabilities provisions of the federal or state securities laws of the United States or would hear actions against us or those persons based on those laws.

Our corporate affairs are governed by the Bermuda Companies Act. The Companies Act differs in some material respects from laws generally applicable to U.S. corporations and shareholders, including the provisions relating to interested directors, amalgamations, mergers and acquisitions, takeovers, shareholder lawsuits and indemnification of directors. Generally, the duties of directors and officers of a Bermuda company are owed to the company only. Shareholders of Bermuda companies generally do not have rights to take action against directors or officers of the company and may only do so in limited circumstances. Class actions and derivative actions are generally not available to shareholders under Bermuda law. The Bermuda courts, however, would ordinarily be expected to permit a shareholder to commence an action in the name of a company to remedy a wrong to the company where the act complained of is alleged to be beyond the corporate power of the company or illegal, or would result in the violation of the company’s memorandum of association or bye-laws. Furthermore, a Bermuda court would ordinarily be expected to permit a shareholder to commence an action that alleges a fraud against noncontrolling shareholders or, for instance, where an act requires the approval of a greater percentage of the company’s shareholders than that which actually approved it.

When the affairs of a company are being conducted in a manner that is oppressive or prejudicial to the interests of some part of the shareholders, one or more shareholders may apply to the Supreme Court of Bermuda, which may make such order as it sees fit, including an order regulating the conduct of the company’s affairs in the future or ordering the purchase of the shares of any shareholders by other shareholders or by the company. Additionally, under our bye-laws and as permitted by Bermuda law, each shareholder has waived any claim or right of action against our directors or officers for any action taken by directors or officers in the performance of their duties, except for actions involving fraud or dishonesty. In addition, the rights of our shareholders and the fiduciary responsibilities of our directors under Bermuda law are not as clearly established as under statutes or judicial precedent in existence in jurisdictions in the United States, particularly the State of Delaware. Therefore, our shareholders may have more difficulty protecting their interests than would shareholders of a corporation incorporated in a jurisdiction within the United States.

***We could be materially adversely affected if our controls designed to ensure compliance with guidelines, policies, and legal and regulatory standards are not effective.***

Our business is highly dependent on our ability to successfully execute a large number of transactions, many of which are complex. These processes are often subject to internal guidelines and policies and government regulation. A control system, no matter how well designed and operated, can provide only reasonable assurance that the control system’s objectives will be met. If controls are not effective, it could lead to unanticipated risk exposure or damage to our reputation and, consequently, could materially adversely affect our results of operations and financial condition.

### Other Risks Related to White Mountains and its Subsidiaries

***We may be unable to adequately maintain our systems and safeguard the security of our data, which could adversely impact our ability to operate our business and cause reputational harm and, consequently, could materially adversely affect our results of operations and financial condition.***

Because our business and operations rely on secure and efficient information technology systems, we depend on our ability, and the ability of certain third parties including vendors and business partners, to access our computer systems to perform necessary functions such as providing quotes and product pricing, billing and processing transactions, administering claims and reporting our financial results. The functioning of these systems may be impacted by any number of events, including power outages, natural and manmade catastrophes and cyber attacks. In the event we are unable to access any of our systems, or any third-party system that we rely upon, our ability to operate our business effectively may be significantly impaired.

Our business also depends upon our ability to securely process, store, transmit and safeguard confidential and proprietary information that is in our possession. This information includes confidential information relating to our business, as well as personally identifiable information (“PII”) and protected health information (“PHI”) belonging to our employees, customers, claimants and business partners. Because our systems may be vulnerable to a variety of forms of unauthorized access that could result in a data breach, including hackers, computer viruses and other cyber attacks, as well as breaches that result from dishonest employees, errors by employees or lost or stolen computer devices, we may not be able to protect the confidentiality of such information.

Third parties present an additional risk of cyber-related events. We outsource certain technological and business process functions to third-party providers. We rely on these third parties to maintain and store PII and PHI and other confidential information on their systems. We also routinely transmit such information by e-mail and other electronic means. Although we attempt to establish sufficient controls and secure capabilities to transmit such information and to prevent unauthorized disclosure, these controls may not be sufficient. Furthermore, third-party providers may not have appropriate controls in place to protect such information.

Our computer systems have been and will continue to be the target of cyber attacks, although we are not aware that we have experienced a material cybersecurity breach. We are also not aware of any third-party vendor having experienced a material cybersecurity breach that materially impacted our data. The risk of a cyber attack may increase, and we may experience more significant attacks in the future.

The risks identified above could expose us to data breaches, disruptions of service, financial losses and significant increases in compliance costs and reputational harm. In addition, a data breach could subject us to legal liability or regulatory action under data protection and privacy laws and regulations enacted by federal, state and foreign governments or other regulatory bodies. As a result, our ability to conduct our business could be adversely impacted, which could materially adversely affect our results of operations and financial condition.

***We may suffer losses from unfavorable outcomes from litigation and other legal proceedings, which could materially adversely affect our results of operations and financial condition.***

From time to time we are subject to legal proceedings. In the event of an unfavorable outcome in one or more legal matters, our ultimate liability may be in excess of amounts we have reserved and such additional amounts could materially adversely affect our results of operations and financial condition. Furthermore, it is possible that these legal proceedings could result in equitable remedies or other unexpected outcomes that could materially adversely affect our results of operations and financial condition.

***We depend on our key personnel to manage our business effectively, and they may be difficult to replace, which could materially adversely affect our results of operations and financial condition.***

Much of our competitive advantage is based on the expertise, experience and know-how of our key personnel. We do not have fixed term employment agreements with any of our key personnel, and the loss of one or more of these key personnel could materially adversely affect our results of operations and financial condition. Our success also depends on the ability to hire and retain additional personnel. Difficulty in hiring or retaining personnel could materially adversely affect our results of operations and financial condition.

## Cybersecurity

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### Risk Management and Strategy

Identifying, assessing and managing cybersecurity risks is an important component of White Mountains’s overall enterprise risk management program. As with the management of risks generally, given our holding company structure, the management of cybersecurity risks involves coordination between the Company and its consolidated subsidiaries/affiliates.

The Company and each of its consolidated subsidiaries/affiliates are responsible for developing a cybersecurity program appropriate for their respective businesses. The design of these cybersecurity programs is informed by the ISO 27001 standards and the Center for Internet Security Critical Security Controls framework (“CISCSC”). This does not imply that these programs meet all specifications of ISO 27001 and CISCSC, but rather that we use them as a guide to help us identify, assess and manage cybersecurity risks relevant to our business. The cybersecurity programs developed by the Company and its consolidated subsidiaries/affiliates include, among other things, (i) advanced threat protection and detection systems; (ii) vulnerability scanning and testing of network defenses; (iii) user authentication, role-based access and privileged access management; (iv) data encryption, loss prevention, backup and recovery mechanisms; (v) employee testing and training; (vi) technical and business team-focused incident response tabletop exercises; (vii) disaster recovery testing and (viii) security assessments of third-party service providers. White Mountains engages both its internal auditors and third-party information security experts to assist management in assessing the effectiveness of these cybersecurity programs.

Risks from cybersecurity threats may cause material disruptions to our operations and reputational harm, which could materially adversely affect our results of operations and financial condition. See ***Item 1.A Risk Factors, “We may be unable to adequately maintain our systems and safeguard the security of our data, which could adversely impact our ability to operate our business and cause reputational harm and, consequently, could materially adversely affect our results of operations and financial condition.”*** on page 41 for more information about these risks.

### Governance

The Company’s Board of Directors has assigned oversight of White Mountains’s cybersecurity risk management to the Audit Committee. The Audit Committee receives periodic reports on White Mountains’s cybersecurity risks and any material cybersecurity incidents at the direction of White Mountains’s senior management. In addition, the Audit Committee receives reports addressing cybersecurity risks as part of the Company’s overall enterprise risk management program.

White Mountains’s Information Technology (“IT”) Steering Committee, which includes its Chief Information Security Officer, Chief Technology Officer and various members of senior management, as well as the senior IT leadership at each of its consolidated subsidiaries/affiliates are responsible for assessing and managing White Mountains’s cybersecurity risk. These individuals include IT and cybersecurity professionals with relevant education, including degrees and/or certifications, and prior work experience. These individuals also monitor the prevention, detection, mitigation and remediation of cybersecurity incidents as part of the cybersecurity programs described above.

Senior IT leadership at our consolidated subsidiaries/affiliates communicate information regarding cybersecurity risks to Company personnel through a variety of channels, including discussions between or among subsidiary/affiliate management and the Company, reports made to subsidiary/affiliate boards and direct updates to the Company’s senior management and/or IT Steering Committee.

## Properties

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The Company maintains two professional offices in Hamilton, Bermuda, which serve as its headquarters and its registered office. The Company’s principal executive office is in Hanover, New Hampshire. In addition, White Mountains maintains professional offices in Guilford, Connecticut, which houses its corporate finance and investment functions, and Boston, Massachusetts, which houses its corporate accounting, reporting and internal audit functions. All of the Company’s professional offices are leased.

Ark’s, WM Outrigger Re’s and HG Global’s headquarters are located in Hamilton, Bermuda. In addition, Ark maintains underwriting offices in London, England and Hamilton, Bermuda. Kudu’s, Distinguished’s and WTM Partners’s headquarters are located in New York, New York.

The various offices and facilities of the consolidated Other Operating Businesses are owned or leased. Management considers its office facilities suitable and adequate for its current level of operations.

## Management's discussion and analysis

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*The following discussion contains “forward-looking statements.” White Mountains intends statements that are not historical in nature, which are hereby identified as forward-looking statements, to be covered by the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. White Mountains cannot promise that its expectations in such forward-looking statements will turn out to be correct. White Mountains’s actual results could be materially different from and worse than its expectations. See “***FORWARD-LOOKING STATEMENTS”** *on page 101 for specific important factors that could cause actual results to differ materially from those contained in forward-looking statements.*

*The following discussion also includes 12 non-GAAP financial measures: (i) Ark’s tangible book value, (ii) Ark’s tangible capital, (iii) Kudu’s earnings before interest, taxes, depreciation and amortization (“EBITDA”), (iv) Kudu’s adjusted EBITDA, (v) Bamboo’s MGA pre-tax income (loss), (vi) Bamboo’s MGA net income (loss), (vii) Bamboo’s MGA EBITDA, (viii) Bamboo’s MGA adjusted EBITDA, (ix) Distinguished’s ScaleCo net income (loss), (x) Distinguished’s ScaleCo EBITDA, (xi) Distinguished’s ScaleCo adjusted EBITDA and (xii) total consolidated portfolio return excluding MediaAlpha that have been reconciled from their most comparable GAAP financial measures on page 85. White Mountains believes these measures to be useful in evaluating White Mountains’s financial performance and condition.*

### RESULTS OF OPERATIONS FOR THE YEARS ENDED DECEMBER 31, 2025, 2024 AND 2023

### Overview—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains ended 2025 with book value per share of $2,188, an increase of 25% for the year, including dividends.

The increase in book value per share was driven primarily by the net gain on sale of the Bamboo Group of approximately $320 per share (based on 2.54 million shares outstanding at December 5, 2025). In addition, the growth in White Mountains’s book value per share reflected solid results at its operating companies and good investment returns.

Comprehensive income attributable to common shareholders was $1,109 million in 2025, largely driven by the net gain on sale of the Bamboo Group, compared to $230 million in 2024. White Mountains also recognized a net deferred tax expense of $73 million in 2025 from the reversal of the deferred tax asset related to the Bermuda economic transition adjustment, of which $51 million was recorded at Ark and $22 million was recorded at HG Global. Due to the enactment of Pillar II legislation by Luxembourg in December 2025, White Mountains no longer expects to utilize the benefit of the Bermuda economic transition adjustment.

On December 5, 2025, White Mountains completed the sale of a controlling financial interest in the Bamboo Group to affiliates of funds advised by CVC. White Mountains sold approximately 77.3% of its equity interest in the Bamboo Group for net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses.

On September 2, 2025, White Mountains closed its transaction to acquire a controlling financial interest in Distinguished, a full-service MGA and program administrator for specialty property & casualty insurance. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction.

On July 18, 2025, White Mountains closed its transaction to deploy $150 million into BroadStreet through the BroadStreet SPV, alongside co-lead investors Ethos Capital LP and British Columbia Investment Management Corporation. BroadStreet is an insurance brokerage company with a presence in all 50 U.S. states and ten Canadian provinces.

On April 1, 2025, White Mountains acquired a majority interest in Enterprise Solutions, a provider of specialty electrical contracting services. This was the first acquisition by WTM Partners. White Mountains paid $58 million of cash consideration, and Enterprise Solutions borrowed $15 million in new debt as part of the transaction.

In 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s December 31, 2025 book value per share. This included 64,064 shares repurchased through the self-tender offer in December.

Including a distribution of $128 million from WM Outrigger Re received in January, undeployed capital stands at roughly $1.0 billion.

The Ark/WM Outrigger segment’s combined ratio was 81% in 2025 compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024.

Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio in 2025 included eight points of catastrophe losses, driven primarily by Hurricane Melissa and losses related to the January 2025 California wildfires, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business.

Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025 compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025 compared to $50 million in 2024. Ark’s results in 2025 also included a $173 million of expense related to the increase in fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment. In November 2025, A.M. Best affirmed Ark’s “A/stable” financial strength rating and upgraded its issuer credit rating to “a+/stable”.

WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in the year ended December 31, 2025 included $19 million of losses related to the California wildfires (net of reinstatement premiums), primarily attributable to the 2024 underwriting year. WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025 compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024.

WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million was attributable to the 2025 underwriting year and $(10) million was attributable to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million was attributable to the 2024 underwriting year and $8 million was attributable to the 2023 underwriting year. Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year.

White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The capital was provided entirely by third-party investors excluding White Mountains.

HG Global reported gross written premiums and earned premiums of $61 million and $31 million in 2025 compared to $52 million and $29 million in 2024. HG Global’s total par value of policies assumed was $3,170 million in 2025 compared to $2,952 million in 2024. HG Global’s total gross pricing was 194 basis points in 2025 compared to 177 basis points in 2024. HG Global reported pre-tax income (loss) of $45 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase of $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM.

The fair value of the BAM Surplus Notes was $339 million as of December 31, 2025 compared to $382 million as of December 31, 2024. The decline was driven by the $38 million decrease in fair value and $35 million in cash payments of principal and interest, partially offset by approximately $30 million of accrued interest.

Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024. Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024.

Kudu deployed $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu has deployed $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management of approximately $153 billion, spanning a range of asset classes.

Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million in the period from January 1, 2025 through December 5, 2025, the date of sale, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million in the period from January 1, 2025 through December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $705 million in the period from January 1, 2025 through December 5, 2025 and $484 million in 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume.

For the period from September 2, 2025, the date of acquisition, through December 31, 2025, Distinguished reported

managed premiums of $188 million, commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo

adjusted EBITDA of $9 million.

As of December 31, 2025, White Mountains owned 17.9 million shares of MediaAlpha, representing a 27.4% basic ownership interest based on the total class A and class B common shares outstanding in MediaAlpha’s Report on Form 10-Q dated October 29, 2025. As of December 31, 2025, MediaAlpha’s share price was $12.95 per share, which increased from $11.29 per share as of December 31, 2024. The carrying value of White Mountains’s investment in MediaAlpha was $231 million as of December 31, 2025, which increased from $202 million as of December 31, 2024. At White Mountains’s current level of ownership, each $1.00 per share increase or decrease in the stock price of MediaAlpha will result in an approximate $7.00 per share increase or decrease in White Mountains’s book value per share.

White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of

net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the

total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024

were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

### Overview—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains ended 2024 with book value per share of $1,746, an increase of 6% for the year, including dividends. Comprehensive income attributable to common shareholders was $230 million in 2024 compared to $511 million in 2023.

Results in 2024 were driven primarily by solid results from White Mountains’s operating businesses and good returns in the investment portfolio. Results in 2023 were driven primarily by good results from White Mountains’s operating businesses and strong returns in the investment portfolio. White Mountains’s results included net realized and unrealized investment gains of $147 million in 2024 compared to $407 million in 2023. Results in 2024 also included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha compared to $27 million in 2023.

As of December 31, 2024, White Mountains’s undeployed capital was approximately $0.7 billion, including the net proceeds received from the debt recapitalization completed in January 2025 at Bamboo.

Ark’s combined ratio was 83% in 2024, compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. The combined ratio in 2024 included four points of net favorable prior year loss reserve development, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year loss reserve development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott.

Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024 compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023. Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment. In November 2024, AM Best affirmed Ark’s financial strength rating at “A/stable.”

WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross and net written premiums of $87 million, net earned premiums of $88 million and pre-tax income of $46 million in 2024, compared to gross and net written premiums of $110 million, net earned premiums of $104 million and pre-tax income of $69 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. During the fourth quarter of 2024, Ark renewed Outrigger Re Ltd. for the 2025 underwriting year. White Mountains’s total commitment toward the 2025 underwriting year is $150 million.

As of July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates.

HG Global reported gross written premiums and earned premiums of $52 million and $29 million in 2024 compared to $50 million and $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024 compared to $2,356 million in 2023. HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023.

Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023. Total revenues and pre-tax income in 2024 included $67 million of net investment income and $51 million of net realized and unrealized investment gains compared to $71 million and $106 million in 2023.

Kudu deployed $104 million, including transaction costs, into two new asset management firms in 2024. As of December 31, 2024, Kudu had deployed $989 million, including transaction costs, into 27 asset and wealth management firms globally, including three that have been exited. As of December 31, 2024, the asset and wealth management firms have combined assets under management of approximately $125 billion, spanning a range of asset classes.

Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million in 2024. Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million in 2024. Managed premiums, which represent the total premium placed by Bamboo, were $484 million in 2024 compared to $215 million in 2023 (prior to White Mountains’s ownership of Bamboo). The increase in managed premiums was driven by growth in new business volume as well as a growing renewal book.

On May 10, 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91 million.

As of December 31, 2024, White Mountains owned 17.9 million shares of MediaAlpha, representing a 26.6% basic ownership interest. As of December 31, 2024, MediaAlpha’s share price was $11.29, which increased from $11.15 per share as of December 31, 2023. The carrying value of White Mountains’s investment in MediaAlpha was $202 million as of December 31, 2024, which decreased from $255 million as of December 31, 2023 as a result of the secondary offering.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios.

### Book Value Per Share

The following table presents White Mountains’s book value per share as of December 31, 2025, 2024 and 2023:

| Book value per share numerators (in millions): | December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| White Mountains’s common shareholders’ equity | **$5,425.4** | $4,483.7 | $4,240.5 |
| **Book value per share denominator (in thousands of shares):** |  |  |  |
| Common shares outstanding | **2,479.7** | 2,568.1 | 2,560.5 |
| **Book value per share** | **$2,187.97** | $1,745.87 | $1,656.14 |
| **Year-to-date dividends paid per share** | **$1.00** | $1.00 | $1.00 |

49

### Goodwill and Other Intangible Assets

The following table presents goodwill and other intangible assets that are included in White Mountains’s book value as of December 31, 2025, 2024 and 2023:

| Millions Goodwill: | December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Ark | **$116.8** | $116.8 | $116.8 |
| Kudu | **7.6** | 7.6 | 7.6 |
| Bamboo | **—** | 270.4 | — |
| Distinguished (1) | **396.7** | — | — |
| Other Operations (1) | **93.0** | 44.4 | 44.4 |
| Total goodwill | **614.1** | 439.2 | 168.8 |
| **Other intangible assets:** |  |  |  |
| Ark | **175.7** | 175.7 | 175.7 |
| Kudu | **.1** | .4 | .7 |
| Bamboo | **—** | 84.6 | — |
| Distinguished (1) | **181.0** | — | — |
| Other Operations (1) | **49.3** | 20.4 | 25.4 |
| Total other intangible assets | **406.1** | 281.1 | 201.8 |
| Total goodwill and other intangible assets (2) | **1,020.2** | 720.3 | 370.6 |
| Total goodwill and other intangible assets attributed to noncontrolling interests (3) | **(378.6)** | (190.5) | (94.9) |
| Total goodwill and other intangible assets included in White Mountains’s common shareholders’ equity | **$641.6** | $529.8 | $275.7 |

(1) The relative fair values of goodwill and other intangible assets recognized in connection with the Distinguished Transaction and the Enterprise Solutions Transaction have not yet been finalized. See **Note 2 — “Significant Transactions”** on page F-19.

(2) See **Note 4 — “Goodwill and Other Intangible Assets”** on page F-34 for details of other intangible assets.

(3) Amounts reflect the basic ownership percentage of the noncontrolling shareholders.

### Summary of Consolidated Results

The following table presents White Mountains’s consolidated financial results by industry for the years ended December 31, 2025, 2024 and 2023:

| Millions Revenues: | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| P&C Insurance and Reinsurance revenues | **$1,943.8** | $1,750.9 | $1,557.8 |
| Financial Guarantee revenues | **73.6** | (44.6) | 92.4 |
| Asset Management revenues | **183.4** | 118.8 | 177.1 |
| P&C Insurance Distribution revenues | **246.3** | 179.8 | — |
| Specialty Insurance Distribution revenues | **57.7** | — | — |
| Other Operations revenues | **1,230.2** | 234.9 | 339.4 |
| **Total revenues** | **3,735.0** | 2,239.8 | 2,166.7 |
| **Expenses:** |  |  |  |
| P&C Insurance and Reinsurance expenses | **1,633.6** | 1,452.1 | 1,240.3 |
| Financial Guarantee expenses | **28.5** | 60.6 | 94.0 |
| Asset Management expenses | **43.8** | 37.5 | 40.6 |
| P&C Insurance Distribution expenses | **206.2** | 147.1 | — |
| Specialty Insurance Distribution expenses | **74.2** | — | — |
| Other Operations expenses | **420.0** | 225.8 | 226.4 |
| **Total expenses** | **2,406.3** | 1,923.1 | 1,601.3 |
| **Pre-tax income (loss):** |  |  |  |
| P&C Insurance and Reinsurance pre-tax income (loss) | **310.2** | 298.8 | 317.5 |
| Financial Guarantee pre-tax income (loss) | **45.1** | (105.2) | (1.6) |
| Asset Management pre-tax income (loss) | **139.6** | 81.3 | 136.5 |
| P&C Insurance Distribution pre-tax income (loss) | **40.1** | 32.7 | — |
| Specialty Insurance Distribution pre-tax income (loss) | **(16.5)** | — | — |
| Other Operations pre-tax income (loss) | **810.2** | 9.1 | 113.0 |
| **Total pre-tax income (loss)** | **1,328.7** | 316.7 | 565.4 |
| **Net income (loss):** |  |  |  |
| Income tax (expense) benefit | **(126.9)** | (32.6) | 15.5 |
| **Net income (loss)** | **1,201.8** | 284.1 | 580.9 |
| Net (income) loss attributable to noncontrolling interests | **(95.4)** | (53.7) | (71.7) |
| **Net income (loss) attributable to White Mountains’s common shareholders** | **1,106.4** | 230.4 | 509.2 |
| **Comprehensive income (loss):** |  |  |  |
| Other comprehensive income (loss), net of tax | **3.7** | (.1) | 2.4 |
| **Comprehensive income (loss)** | **1,110.1** | 230.3 | 511.6 |
| Other comprehensive (income) loss attributable to noncontrolling interests | **(1.2)** | — | (.5) |
| **Comprehensive income (loss) attributable to White Mountains’s common shareholders** | **$1,108.9** | $230.3 | $511.1 |

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### I. SUMMARY OF OPERATIONS BY SEGMENT

As of December 31, 2025, White Mountains conducted its operations through four reportable segments: (1) Ark/WM Outrigger, (2) HG Global, (3) Kudu and (4) Distinguished, with our remaining operating businesses, holding companies and other assets included in Other Operations. White Mountains has made its segment determination based on consideration of the following criteria: (i) the nature of the business activities of each of the Company’s subsidiaries and affiliates; (ii) the manner in which the Company’s subsidiaries and affiliates are organized; (iii) the existence of primary managers responsible for specific subsidiaries and affiliates; and (iv) the organization of information provided to the Company’s chief operating decision makers and its Board of Directors. Significant intercompany transactions among White Mountains’s segments have been eliminated herein. White Mountains’s segment information is presented in **Note 15 — “Segment Information”** on page F-70.

During the fourth quarter of 2022, Ark sponsored the formation of Outrigger Re Ltd. to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio written in the 2023 underwriting year. Ark renewed its quota share reinsurance agreement with Outrigger Re Ltd. for the 2024, 2025 and 2026 underwriting years. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements. WM Outrigger Re’s quota share reinsurance agreement with GAIL eliminates in White Mountains’s consolidated financial statements. WM Outrigger Re exclusively provides reinsurance protection to Ark. As a result, WM Outrigger Re was aggregated with Ark within the Ark/WM Outrigger segment starting in 2023. See **Note 2 — “Significant Transactions”** on page F-19.

Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, BAM’s results of operations, are presented within the HG Global segment. See **Note 2 — “Significant Transactions”** on page F-19.

On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations, are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See **Note 2 — “Significant Transactions”** on page F-19.

On September 2, 2025, White Mountains completed the Distinguished Transaction. As a result, White Mountains began consolidating Distinguished in its financial statements on September 2, 2025. See **Note 2 — “Significant Transactions”** on page F-19.

A discussion of White Mountains’s consolidated investment operations is included after the discussion of operations by segment.

### Ark/WM Outrigger

Ark is a specialty property and casualty insurance and reinsurance company that offers a wide range of niche insurance and reinsurance products, including property, specialty, marine & energy, casualty and accident & health. Ark underwrites select coverages through its two major subsidiaries in the United Kingdom and Bermuda.

Ark sponsored the formation of Outrigger Re Ltd., a Bermuda company registered as a special purpose insurer and segregated accounts company, to provide collateralized reinsurance protection on Ark’s Bermuda global property catastrophe excess of loss portfolio. White Mountains consolidates its segregated account of Outrigger Re Ltd., WM Outrigger Re, in its financial statements.

The following tables present the components of pre-tax income (loss) included in the Ark/WM Outrigger segment for the years ended December 31, 2025, 2024 and 2023:

| Millions | Year Ended December 31, 2025 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Direct written premiums | **$1,260.1** | **$—** | **$—** | **$1,260.1** |
| Assumed written premiums | **1,297.1** | **84.2** | **(84.2)** | **1,297.1** |
| Gross written premiums | **2,557.2** | **84.2** | **(84.2)** | **2,557.2** |
| Ceded written premiums | **(829.8)** | **—** | **84.2** | **(745.6)** |
| Net written premiums | **$1,727.4** | **$84.2** | **$—** | **$1,811.6** |
| Earned insurance premiums | **$1,612.8** | **$84.6** | **$—** | **$1,697.4** |
| Net investment income | **97.4** | **9.1** | **—** | **106.5** |
| Net realized and unrealized investment gains (losses) | **124.6** | **—** | **—** | **124.6** |
| Other revenues | **15.3** | **—** | **—** | **15.3** |
| Total revenues | **1,850.1** | **93.7** | **—** | **1,943.8** |
| Loss and LAE | **818.8** | **25.4** | **—** | **844.2** |
| Acquisition expenses | **371.1** | **23.1** | **—** | **394.2** |
| General and administrative expenses - other underwriting | **143.9** | **—** | **—** | **143.9** |
| General and administrative expenses - all other | **61.1** | **.1** | **—** | **61.2** |
| Change in fair value of contingent consideration | **173.0** | **—** | **—** | **173.0** |
| Interest expense | **17.1** | **—** | **—** | **17.1** |
| Total expenses | **1,585.0** | **48.6** | **—** | **1,633.6** |
| Pre-tax income (loss) | **$265.1** | **$45.1** | **$—** | **$310.2** |

| Millions | Year Ended December 31, 2024 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Direct written premiums | $1,101.5 | $— | $— | $1,101.5 |
| Assumed written premiums | 1,105.5 | 86.5 | (86.5) | 1,105.5 |
| Gross written premiums | 2,207.0 | 86.5 | (86.5) | 2,207.0 |
| Ceded written premiums | (614.4) | — | 86.5 | (527.9) |
| Net written premiums | $1,592.6 | $86.5 | $— | $1,679.1 |
| Earned insurance premiums | $1,499.8 | $88.0 | $— | $1,587.8 |
| Net investment income | 79.4 | 11.3 | — | 90.7 |
| Net realized and unrealized investment gains (losses) | 50.1 | — | — | 50.1 |
| Other revenues | 22.3 | — | — | 22.3 |
| Total revenues | 1,651.6 | 99.3 | — | 1,750.9 |
| Loss and LAE | 825.9 | 29.9 | — | 855.8 |
| Acquisition expenses | 283.9 | 23.2 | — | 307.1 |
| General and administrative expenses - other underwriting | 136.1 | — | — | 136.1 |
| General and administrative expenses - all other | 72.2 | .1 | — | 72.3 |
| Change in fair value of contingent consideration | 61.3 | — | — | 61.3 |
| Interest expense | 19.5 | — | — | 19.5 |
| Total expenses | 1,398.9 | 53.2 | — | 1,452.1 |
| Pre-tax income (loss) | $252.7 | $46.1 | $— | $298.8 |

53

| Millions | Year Ended December 31, 2023 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Direct written premiums | $931.9 | $— | $— | $931.9 |
| Assumed written premiums | 966.5 | 110.0 | (110.0) | 966.5 |
| Gross written premiums | 1,898.4 | 110.0 | (110.0) | 1,898.4 |
| Ceded written premiums | (487.5) | — | 110.0 | (377.5) |
| Net written premiums | $1,410.9 | $110.0 | $— | $1,520.9 |
| Earned insurance premiums | $1,305.4 | $104.3 | $— | $1,409.7 |
| Net investment income | 50.4 | 11.0 | — | 61.4 |
| Net realized and unrealized investment gains (losses) | 85.9 | — | — | 85.9 |
| Other revenues | .8 | — | — | .8 |
| Total revenues | 1,442.5 | 115.3 | — | 1,557.8 |
| Loss and LAE | 711.2 | 15.6 | — | 726.8 |
| Acquisition expenses | 251.0 | 30.5 | — | 281.5 |
| General and administrative expenses - other underwriting | 113.6 | — | — | 113.6 |
| General and administrative expenses - all other | 48.1 | .3 | — | 48.4 |
| Change in fair value of contingent consideration | 48.7 | — | — | 48.7 |
| Interest expense | 21.3 | — | — | 21.3 |
| Total expenses | 1,193.9 | 46.4 | — | 1,240.3 |
| Pre-tax income (loss) | $248.6 | $68.9 | $— | $317.5 |

### Combined Ratio

The following tables present the Ark/WM Outrigger segment’s insurance premiums, insurance expenses and insurance ratios for the years ended December 31, 2025, 2024 and 2023:

*$ in Millions*

| Insurance premiums: | Year Ended December 31, 2025 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Gross written premiums | **$2,557.2** | **$84.2** | **$(84.2)** | **$2,557.2** |
| Net written premiums | **$1,727.4** | **$84.2** | **$—** | **$1,811.6** |
| Net earned premiums | **$1,612.8** | **$84.6** | **$—** | **$1,697.4** |
| Insurance expenses: |  |  |  |  |
| Loss and LAE | **$818.8** | **$25.4** | **$—** | **$844.2** |
| Acquisition expenses | **371.1** | **23.1** | **—** | **394.2** |
| Other underwriting expenses (1) | **143.9** | **—** | **—** | **143.9** |
| Total insurance expenses | **$1,333.8** | **$48.5** | **$—** | **$1,382.3** |
| Insurance ratios: |  |  |  |  |
| Loss and LAE | **50.8%** | **30.0%** | **—%** | **49.7%** |
| Acquisition expense | **23.0** | **27.3** | **—** | **23.2** |
| Other underwriting expense | **8.9** | **—** | **—** | **8.5** |
| Combined Ratio | **82.7%** | **57.3%** | **—%** | **81.4%** |

(1) Included within general and administrative expenses in the consolidated statement of operations.

*$ in Millions*

| Insurance premiums: | Year Ended December 31, 2024 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Gross written premiums | $2,207.0 | $86.5 | $(86.5) | $2,207.0 |
| Net written premiums | $1,592.6 | $86.5 | $— | $1,679.1 |
| Net earned premiums | $1,499.8 | $88.0 | $— | $1,587.8 |
| Insurance expenses: |  |  |  |  |
| Loss and LAE | $825.9 | $29.9 | $— | $855.8 |
| Acquisition expenses | 283.9 | 23.2 | — | 307.1 |
| Other underwriting expenses (1) | 136.1 | — | — | 136.1 |
| Total insurance expenses | $1,245.9 | $53.1 | $— | $1,299.0 |
| Insurance ratios: |  |  |  |  |
| Loss and LAE | 55.1% | 34.0% | —% | 53.9% |
| Acquisition expense | 18.9 | 26.3 | — | 19.3 |
| Other underwriting expense | 9.1 | — | — | 8.6 |
| Combined Ratio | 83.1% | 60.3% | —% | 81.8% |

(1) Included within general and administrative expenses in the consolidated statement of operations.

*$ in Millions*

| Insurance premiums: | Year Ended December 31, 2023 Ark | WM Outrigger Re | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Gross written premiums | $1,898.4 | $110.0 | $(110.0) | $1,898.4 |
| Net written premiums | $1,410.9 | $110.0 | $— | $1,520.9 |
| Net earned premiums | $1,305.4 | $104.3 | $— | $1,409.7 |
| Insurance expenses: |  |  |  |  |
| Loss and LAE | $711.2 | $15.6 | $— | $726.8 |
| Acquisition expenses | 251.0 | 30.5 | — | 281.5 |
| Other underwriting expenses (1) | 113.6 | — | — | 113.6 |
| Total insurance expenses | $1,075.8 | $46.1 | $— | $1,121.9 |
| Insurance ratios: |  |  |  |  |
| Loss and LAE | 54.5% | 15.0% | —% | 51.6% |
| Acquisition expense | 19.2 | 29.2 | — | 20.0 |
| Other underwriting expense | 8.7 | — | — | 8.0 |
| Combined Ratio | 82.4% | 44.2% | —% | 79.6% |

(1) Included within general and administrative expenses in the consolidated statement of operations.

The following table presents WM Outrigger Re’s insurance premiums, combined ratio and pre-tax income by underwriting year for the years ended December 31, 2025, 2024 and 2023:

*$ in Millions*

| Insurance premiums: | Year Ended December 31, 2025 2025 Underwriting Year | 2024 Underwriting Year | 2023 Underwriting Year | Total |
| --- | ---: | ---: | ---: | ---: |
| Gross written premiums | **$82.8** | **$1.4** | **$—** | **$84.2** |
| Net written premiums | **$82.8** | **$1.4** | **$—** | **$84.2** |
| Net earned premiums | **$78.9** | **$5.7** | **$—** | **$84.6** |
| Combined Ratio | **42.2%** | **266.5%** | **—%** | **57.3%** |
| Pre-tax income | **$54.7** | **$(9.6)** | **$—** | **$45.1** |

*$ in Millions*

| Insurance premiums: | Year Ended December 31, 2024 2024 Underwriting Year | 2023 Underwriting Year | Total | 2023 2023 Underwriting Year |
| --- | ---: | ---: | ---: | ---: |
| Gross written premiums | $87.3 | $(.8) | $86.5 | $110.0 |
| Net written premiums | $87.3 | $(.8) | $86.5 | $110.0 |
| Net earned premiums | $83.0 | $5.0 | $88.0 | $104.3 |
| Combined Ratio | 67.2% | (53.8)% | 60.3% | 44.2% |
| Pre-tax income | $38.5 | $7.6 | $46.1 | $68.9 |

Through December 31, 2025, WM Outrigger Re has generated pre-tax income of $55 million from the 2025 underwriting year, $29 million from the 2024 underwriting year and $76 million from the 2023 underwriting year.

White Mountains’s capital commitment to WM Outrigger Re was $150 million for the 2025 underwriting year, $130 million for the 2024 underwriting year and $205 million for the 2023 underwriting year. During the fourth quarter of 2025, Ark renewed Outrigger Re Ltd. for the 2026 underwriting year with $70 million of capital. The reduced capacity at Outrigger Re Ltd. was replaced by Ark through traditional quota share reinsurance agreements. The capital was provided entirely by third-party investors excluding White Mountains.

### Ark/WM Outrigger Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

Ark/WM Outrigger segment’s combined ratio was 81% in 2025, compared to 82% in 2024. The Ark/WM Outrigger segment reported gross written premiums of $2,557 million, net written premiums of $1,812 million and net earned premiums of $1,697 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024. The Ark/WM Outrigger segment reported pre-tax income of $310 million in 2025 compared to $299 million in 2024.

Ark’s combined ratio was 83% in both 2025 and 2024. Ark’s combined ratio included eight points of catastrophe losses in 2025, driven primarily by Hurricane Melissa as well as losses related to the January 2025 California wildfires of $78 million on a net basis after reinsurance and reinstatement premiums, compared to 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl. Ark’s combined ratio included seven points of net favorable prior year development in 2025, driven primarily by property and specialty lines of business. This included six points of unfavorable development related to aviation losses from the conflict in Ukraine and Russia. This compares to four points of net favorable prior year development in 2024, driven primarily by property and specialty lines of business.

Ark reported gross written premiums of $2,557 million, net written premiums of $1,727 million and net earned premiums of $1,613 million in 2025, compared to gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business.

Ark reported pre-tax income of $265 million in 2025 compared to $253 million in 2024. Ark’s results included net realized and unrealized investment gains of $125 million in 2025, driven primarily by net unrealized investment gains on other long-term investments and common equity securities and net foreign currency gains, compared to $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses. Ark’s results in 2025 also included a $173 million increase in the fair value of contingent consideration compared to $61 million in 2024. The increase in the contingent consideration liability was driven primarily by strong growth in Ark’s tangible book value in the year. See “***Contingent Consideration Liabilities”*** in **Note 1 — “Basis of Presentation and Significant Accounting Policies”** on page F-18. Ark’s results in 2025 also included the reversal of the $51 million deferred tax asset associated with the Bermuda economic transition adjustment.

WM Outrigger Re’s combined ratio was 57% in 2025, compared to 60% in 2024. Catastrophe losses in 2025 included $19 million of losses related to the California wildfires, net of reinstatement premiums. WM Outrigger Re’s losses related to the California wildfires were $2 million for the 2025 underwriting year and $17 million for the 2024 underwriting year. Catastrophe losses in 2024 included Hurricanes Milton, Helene, Debby and Beryl. In 2025, WM Outrigger Re’s combined ratio was 42% for the 2025 underwriting year and 267% for the 2024 underwriting year. In 2024, WM Outrigger Re’s combined ratio was 67% for the 2024 underwriting year and (54)% for the 2023 underwriting year.

WM Outrigger Re reported gross written premiums of $84 million and net earned premiums of $85 million in 2025, compared to gross written premiums of $87 million and net earned premiums of $88 million in 2024. WM Outrigger Re reported pre-tax income (loss) of $45 million in 2025, of which $55 million related to the 2025 underwriting year and $(10) million related to the 2024 underwriting year. WM Outrigger Re reported pre-tax income of $46 million in 2024, of which $38 million related to the 2024 underwriting year and $8 million related to the 2023 underwriting year.

### Ark/WM Outrigger Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Ark/WM Outrigger segment’s combined ratio was 82% in 2024, compared to 80% in 2023. The Ark/WM Outrigger segment reported gross written premiums of $2,207 million, net written premiums of $1,679 million and net earned premiums of $1,588 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,521 million and net earned premiums of $1,410 million in 2023. The Ark/WM Outrigger segment reported pre-tax income of $299 million in 2024 compared to $318 million in 2023.

Ark’s combined ratio was 83% in 2024 compared to 82% in 2023. Ark’s combined ratio included 13 points of catastrophe losses in 2024, driven primarily by Hurricanes Milton, Helene, Debby and Beryl, compared to two points of catastrophe losses in 2023, driven primarily by Hurricanes Otis and Idalia as well as the Maui wildfires. Ark’s combined ratio included four points of net favorable prior year development in 2024, driven primarily by specialty and property lines of business, compared to two points of net unfavorable prior year development in 2023, driven primarily by Hurricane Ian and Winter Storm Elliott, partially offset by net favorable prior year loss reserve development within the specialty and casualty–runoff reserving lines of business.

Ark reported gross written premiums of $2,207 million, net written premiums of $1,593 million and net earned premiums of $1,500 million in 2024, compared to gross written premiums of $1,898 million, net written premiums of $1,411 million and net earned premiums of $1,305 million in 2023.

Ark reported pre-tax income of $253 million in 2024 compared to $249 million in 2023. Ark’s results included net realized and unrealized investment gains (losses) of $50 million in 2024, driven primarily by net unrealized investment gains on other long-term investments and common equity securities, partially offset by net foreign currency losses, compared to $86 million in 2023, driven primarily by net unrealized investment gains on other long-term investments, fixed maturity investments and common equity securities. Ark’s results in 2024 also included a $61 million increase in the fair value of contingent consideration compared to $49 million in 2023. Ark’s results in 2023 included a $51 million net deferred tax benefit related to the Bermuda economic transition adjustment.

WM Outrigger Re’s combined ratio was 60% in 2024, compared to 44% in 2023. The 2024 combined ratio included catastrophe losses from Hurricanes Milton, Helene, Debby and Beryl. Major catastrophe losses affecting WM Outrigger Re in 2023 were minimal. WM Outrigger Re reported gross written premiums of $87 million and net earned premiums of $88 million in 2024, compared to gross written premiums of $110 million and net earned premiums of $104 million in 2023. Net earned premiums in 2024 decreased due to White Mountains’s lower capital commitment to WM Outrigger Re in 2024 compared to 2023. WM Outrigger Re reported pre-tax income of $46 million in 2024, compared to pre-tax income of $69 million in 2023.

### Gross Written Premiums

Ark’s gross written premiums increased 16% to $2,557 million in 2025 compared to $2,207 million in 2024, with risk adjusted rate change of -4%. The increase in gross written premiums was driven primarily by the addition of new underwriting teams and classes of business in the property and specialty lines of business. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -5% in 2025.

Ark’s gross written premiums increased 16% to $2,207 million in 2024 compared to $1,898 million in 2023, with flat risk adjusted rate change. The increase in gross written premiums was across all lines of business but driven primarily by structured property transactions placed in Bermuda and the addition of new products and underwriting teams, including accident & health, marine liability and political violence. The risk adjusted rate change on the Outrigger Re Ltd. portfolio of global property reinsurance was -3% in 2024.

The following table presents Ark’s gross written premiums by line of business for the years ended December 31, 2025, 2024 and 2023:

| Millions | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Property | **$1,178.0** | $1,080.8 | $917.0 |
| Specialty | **646.7** | 450.0 | 436.6 |
| Marine & Energy | **453.6** | 449.6 | 375.7 |
| Casualty | **168.8** | 130.6 | 98.7 |
| Accident & Health | **110.1** | 96.0 | 70.4 |
| Total Gross Written Premium | **$2,557.2** | $2,207.0 | $1,898.4 |

58

### Ark/WM Outrigger Balance Sheets

The following tables present amounts from Ark and WM Outrigger Re that are contained within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024:

| Millions Assets | December 31, 2025 Ark | WM Outrigger Re | Eliminations and Segment Adjustments | Total |
| --- | ---: | ---: | ---: | ---: |
| Fixed maturity investments, at fair value | **$1,917.9** | **$—** | **$—** | **$1,917.9** |
| Common equity securities, at fair value | **452.3** | **—** | **—** | **452.3** |
| Short-term investments, at fair value | **620.9** | **245.7** | **—** | **866.6** |
| Other long-term investments | **689.7** | **—** | **—** | **689.7** |
| Total investments | **3,680.8** | **245.7** | **—** | **3,926.5** |
| Cash | **104.7** | **.1** | **—** | **104.8** |
| Reinsurance recoverables | **874.7** | **—** | **(38.6)** | **836.1** |
| Insurance premiums receivable | **848.4** | **23.9** | **(23.9)** | **848.4** |
| Deferred acquisition costs | **210.4** | **.7** | **—** | **211.1** |
| Goodwill and other intangible assets | **292.5** | **—** | **—** | **292.5** |
| Other assets | **134.7** | **—** | **—** | **134.7** |
| Total assets | **$6,146.2** | **$270.4** | **$(62.5)** | **$6,354.1** |
| Liabilities |  |  |  |  |
| Loss and LAE | **$2,481.0** | **$34.7** | **$(34.7)** | **$2,481.0** |
| Unearned insurance premiums | **1,026.1** | **3.9** | **(3.9)** | **1,026.1** |
| Debt | **159.7** | **—** | **—** | **159.7** |
| Reinsurance payable | **310.1** | **—** | **(23.9)** | **286.2** |
| Contingent consideration | **328.3** | **—** | **—** | **328.3** |
| Other liabilities | **247.1** | **.1** | **—** | **247.2** |
| Total liabilities | **4,552.3** | **38.7** | **(62.5)** | **4,528.5** |
| Equity |  |  |  |  |
| White Mountains’s common shareholders’ equity | **1,128.7** | **231.7** | **—** | **1,360.4** |
| Noncontrolling interests | **465.2** | **—** | **—** | **465.2** |
| Total equity | **1,593.9** | **231.7** | **—** | **1,825.6** |
| Total liabilities and equity | **$6,146.2** | **$270.4** | **$(62.5)** | **$6,354.1** |
| Tangible book value and tangible capital: |  |  |  |  |
| Total equity | **$1,593.9** | **$231.7** | **$—** | **$1,825.6** |
| Less: goodwill and other intangible assets, net (1) | **(248.6)** | **—** | **—** | **(248.6)** |
| Plus: contingent consideration | **328.3** | **—** | **—** | **328.3** |
| Total tangible book value (2) | **1,673.6** | **231.7** | **—** | **1,905.3** |
| Debt | **159.7** | **—** | **—** | **159.7** |
| Total tangible capital (2) | **$1,833.3** | **$231.7** | **$—** | **$2,065.0** |

(1) Amount is net of $43.9 in deferred tax liabilities related to the intangible assets.

(2) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

| Millions Assets | December 31, 2024 Ark | WM Outrigger Re | Eliminations and Segment Adjustments | Total |
| --- | ---: | ---: | ---: | ---: |
| Fixed maturity investments, at fair value | $1,565.1 | $— | $— | $1,565.1 |
| Common equity securities, at fair value | 425.4 | — | — | 425.4 |
| Short-term investments, at fair value | 397.7 | 203.7 | — | 601.4 |
| Other long-term investments | 547.8 | — | — | 547.8 |
| Total investments | 2,936.0 | 203.7 | — | 3,139.7 |
| Cash | 141.1 | .1 | — | 141.2 |
| Reinsurance recoverables | 628.2 | — | (39.2) | 589.0 |
| Insurance premiums receivable | 768.6 | 30.9 | (30.9) | 768.6 |
| Deferred acquisition costs | 164.4 | .8 | — | 165.2 |
| Goodwill and other intangible assets | 292.5 | — | — | 292.5 |
| Other assets | 202.8 | — | — | 202.8 |
| Total assets | $5,133.6 | $235.5 | $(70.1) | $5,299.0 |
| Liabilities |  |  |  |  |
| Loss and LAE | $2,127.5 | $34.9 | $(34.9) | $2,127.5 |
| Unearned insurance premiums | 853.3 | 4.3 | (4.3) | 853.3 |
| Debt | 154.5 | — | — | 154.5 |
| Reinsurance payable | 180.4 | — | (30.9) | 149.5 |
| Contingent consideration | 155.3 | — | — | 155.3 |
| Other liabilities | 224.7 | — | — | 224.7 |
| Total liabilities | 3,695.7 | 39.2 | (70.1) | 3,664.8 |
| Equity |  |  |  |  |
| White Mountains’s common shareholders’ equity | 1,027.5 | 196.3 | — | 1,223.8 |
| Noncontrolling interests | 410.4 | — | — | 410.4 |
| Total equity | 1,437.9 | 196.3 | — | 1,634.2 |
| Total liabilities and equity | $5,133.6 | $235.5 | $(70.1) | $5,299.0 |
| Tangible book value and tangible capital: |  |  |  |  |
| Total equity | $1,437.9 | $196.3 | $— | $1,634.2 |
| Less: goodwill and other intangible assets, net (1) | (248.6) | — | — | (248.6) |
| Plus: contingent consideration | 155.3 | — | — | 155.3 |
| Total tangible book value (2) | 1,344.6 | 196.3 | — | 1,540.9 |
| Debt | 154.5 | — | — | 154.5 |
| Total tangible capital (2) | $1,499.1 | $196.3 | $— | $1,695.4 |

(1) Amount is net of $43.9 in deferred tax liabilities related to the intangible assets.

(2) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

### HG Global

HG Global was established to fund the startup of BAM and, through its reinsurance subsidiary HG Re, to provide up to 15%-of-par, first-loss reinsurance protection for policies underwritten by BAM.

The following tables present the components of pre-tax income (loss) included in the HG Global segment for the years ended December 31, 2025, 2024 and 2023. The HG Global segment consists of HG Global, which includes HG Re and its other wholly-owned subsidiaries, and, prior to its deconsolidation on July 1, 2024, BAM. Through June 30, 2024, BAM’s results of operations are presented within the HG Global segment.

| Millions | December 31, 2025 |
| --- | ---: |
| Direct written premiums | **$—** |
| Assumed written premiums | **61.4** |
| Gross written premiums | **61.4** |
| Ceded written premiums | **—** |
| Net written premiums | **$61.4** |
| Earned insurance premiums | **$30.8** |
| Net investment income | **27.1** |
| Net realized and unrealized investment gains (losses) | **23.2** |
| Interest income from BAM Surplus Notes | **29.8** |
| Change in fair value of BAM Surplus Notes | **(37.5)** |
| Other revenues (1) | **1.0** |
| Total revenues | **74.4** |
| Acquisition expenses | **8.0** |
| General and administrative expenses | **3.1** |
| Interest expense | **17.4** |
| Total expenses | **28.5** |
| **Pre-tax income (loss)** | **$45.9** |

(1) Amount includes $0.8 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations.

| Millions | December 31, 2024 HG Global | BAM (1) | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Direct written premiums | $— | $24.1 | $— | $24.1 |
| Assumed written premiums | 52.4 | — | (20.5) | 31.9 |
| Gross written premiums | 52.4 | 24.1 | (20.5) | 56.0 |
| Ceded written premiums | — | (20.5) | 20.5 | — |
| Net written premiums | $52.4 | $3.6 | $— | $56.0 |
| Earned insurance premiums | $28.9 | $2.8 | $— | $31.7 |
| Net investment income | 23.4 | 8.8 | — | 32.2 |
| Net realized and unrealized investment gains (losses) | (6.4) | (5.1) | — | (11.5) |
| Interest income from BAM Surplus Notes | 29.0 | — | (13.2) | 15.8 |
| Change in fair value of BAM Surplus Notes | .5 | — | — | .5 |
| Unrealized loss on deconsolidation of BAM (2) | (114.5) | — | — | (114.5) |
| Other revenues (3) | .6 | 1.1 | — | 1.7 |
| Total revenues | (38.5) | 7.6 | (13.2) | (44.1) |
| Acquisition expenses | 7.8 | .4 | — | 8.2 |
| General and administrative expenses | 2.2 | 33.5 | — | 35.7 |
| Interest expense (4) | 17.7 | — | — | 17.7 |
| Interest expense from BAM Surplus Notes | — | 13.2 | (13.2) | — |
| Total expenses | 27.7 | 47.1 | (13.2) | 61.6 |
| Pre-tax income (loss) | $(66.2) | $(39.5) | $— | $(105.7) |
| **Supplemental information:** |  |  |  |  |
| MSC collected (5) | $— | $26.0 | $— | $26.0 |

(1) Effective July 1, 2024, White Mountains no longer consolidates BAM. For the period from January 1, 2024 through June 30, 2024, BAM’s results of operations were presented within the HG Global segment.

(2) Upon the deconsolidation of BAM, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387.4, which resulted in an unrealized loss on deconsolidation of $114.5.

(3) Amount includes $0.5 of intercompany revenues that are eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany revenues included within the HG Global segment are eliminated against the offsetting intercompany expense included within Other Operations

(4) Amount includes $1.0 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations.

(5) MSC collected are recorded directly to BAM’s equity, which was recorded as noncontrolling interests on White Mountains’s balance sheet through June 30, 2024.

| Millions | December 31, 2023 HG Global | BAM | Eliminations | Total |
| --- | ---: | ---: | ---: | ---: |
| Direct written premiums | $— | $58.6 | $— | $58.6 |
| Assumed written premiums | 50.1 | — | (50.1) | — |
| Gross written premiums | 50.1 | 58.6 | (50.1) | 58.6 |
| Ceded written premiums | — | (50.1) | 50.1 | — |
| Net written premiums | $50.1 | $8.5 | $— | $58.6 |
| Earned insurance premiums | $26.0 | $5.2 | $— | $31.2 |
| Net investment income | 17.1 | 14.6 | — | 31.7 |
| Net realized and unrealized investment gains (losses) | 13.6 | 13.0 | — | 26.6 |
| Interest income from BAM Surplus Notes | 26.2 | — | (26.2) | — |
| Other revenues | — | 2.9 | — | 2.9 |
| Total revenues | 82.9 | 35.7 | (26.2) | 92.4 |
| Acquisition expenses | 7.4 | 1.2 | — | 8.6 |
| General and administrative expenses | 2.8 | 66.1 | — | 68.9 |
| Interest expense (1) | 17.0 | — | — | 17.0 |
| Interest expense from BAM Surplus Notes | — | 26.2 | (26.2) | — |
| Total expenses | 27.2 | 93.5 | (26.2) | 94.5 |
| Pre-tax income (loss) | $55.7 | $(57.8) | $— | $(2.1) |
| **Supplemental information:** |  |  |  |  |
| MSC collected (2) | $— | $72.8 | $— | $72.8 |

(1) Amount includes $0.5 of intercompany interest expense that is eliminated in White Mountains’s consolidated financial statements. For segment reporting, HG Global’s intercompany interest expense included within the HG Global segment is eliminated against the offsetting intercompany interest income included within Other Operations.

(2) MSC collected are recorded directly to BAM’s equity, which is recorded as noncontrolling interests on White Mountains’s balance sheet.

### HG Global Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

HG Global reported gross written premiums of $61 million and earned premiums of $31 million in 2025 compared to gross written premiums of $52 million and earned premiums of $29 million in 2024. HG Global reported gross written premiums net of ceding commission paid of $43 million in 2025 compared to $37 million in 2024. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $3,170 million in 2025, of which $2,718 million was in the primary market and $452 million in the secondary market, compared to $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market. The increase in primary market par assumed was driven by increased municipal bond issuance. The increase in secondary market par assumed was driven by increased uncertainty in financial markets, which created more demand for bond insurance.

HG Global’s total gross pricing was 194 basis points in 2025, compared to 177 basis points in 2024. Pricing in the primary market increased to 160 basis points in 2025 compared to 140 basis points in 2024, due to an increase in the volume of large, higher-priced issuances insured by BAM in 2025. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, decreased to 398 basis points in 2025 compared to 464 basis points in 2024, due to a decrease in the volume and pricing of larger secondary market issuances insured by BAM in 2025. Total pricing net of ceding commission paid increased to 136 basis points in 2025 compared to 125 basis points in 2024.

The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2025 and 2024:

*$ in Millions*

| Par value assumed: | Year Ended December 31, 2025 | 2024 |
| --- | ---: | ---: |
| Par value of primary market policies assumed (1) | **$2,718.2** | $2,614.0 |
| Par value of secondary market policies assumed (1) | **451.8** | 338.4 |
| Total par value of policies assumed | **$3,170.0** | $2,952.4 |
| Reinsurance premiums: |  |  |
| Gross written premiums from primary market | **$43.4** | $36.7 |
| Gross written premiums from secondary market | **18.0** | 15.7 |
| Total gross written premiums | **61.4** | 52.4 |
| Ceding commission paid | **18.3** | 15.4 |
| Total gross written premiums net of ceding commission paid | **$43.1** | $37.0 |
| Earned premiums | **$30.8** | $28.9 |
| Pricing: |  |  |
| Gross pricing from primary market | **160** **bps** | 140 bps |
| Gross pricing from secondary market | **398** **bps** | 464 bps |
| Total gross pricing | **194** **bps** | 177 bps |
| Total pricing net of ceding commission paid | **136** **bps** | 125 bps |

(1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds.

HG Global reported pre-tax income (loss) of $46 million in 2025 compared to $(66) million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $23 million in 2025 compared to $(6) million in 2024, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $30 million in 2025 compared to $29 million in 2024. HG Global’s results in 2025 included a $38 million decline in the fair value of the BAM surplus notes, which was driven by changes in certain key inputs used in the discounted cash flow analysis. HG Global’s results in 2024 included an increase $1 million in the fair value of the BAM surplus notes. In addition, HG Global’s results in 2024 included the $115 million unrealized loss on deconsolidation of BAM. See **Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes”** on page F-61. HG Global’s results in 2025 also included the reversal of the $22 million deferred tax asset associated with the Bermuda economic transition adjustment.

During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust.

During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust.

During 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $30 million and a cash distribution of $31 million. During 2024, HG Re received a distribution from the Supplemental Trust of $80 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $59 million and a cash distribution of $21 million.

### HG Global Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Effective July 1, 2024, White Mountains no longer consolidates BAM. Upon deconsolidation, the BAM Surplus Notes, including accrued interest receivable, were fair valued in accordance with GAAP at $387 million, which resulted in an unrealized loss on deconsolidation of $115 million. As of December 31, 2024, the BAM Surplus Notes were fair valued at $382 million. The decrease in fair value of $5 million was driven by a $22 million cash payment of principal and interest, partially offset by $16 million of accrued interest and a $1 million increase in fair value as a result of lower market interest rates.

HG Global reported gross written premiums of $52 million and earned premiums of $29 million in 2024 compared to gross written premiums of $50 million and earned premiums of $26 million in 2023. HG Global reported gross written premiums net of ceding commission paid of $37 million in 2024 compared to $35 million in 2023. HG Global’s total par value of policies assumed, which represents its first-loss exposure on policies assumed from BAM, was $2,952 million in 2024, of which $2,614 million was in the primary market and $338 million in the secondary market, compared to $2,356 million in 2023, of which $1,930 million was in the primary market and $426 million in the secondary market.

HG Global’s total gross pricing was 177 basis points in 2024 compared to 213 basis points in 2023. Pricing in the primary market decreased to 140 basis points in 2024 compared to 164 basis points in 2023, due to tighter municipal bond spreads and an increase in the volume of large, higher-credit issuances insured by BAM. Pricing in the secondary market, which is more transaction specific than pricing in the primary market, increased to 464 basis points in 2024 compared to 434 basis points in 2023. Total pricing net of ceding commission paid decreased to 125 basis points in 2024 compared to 148 basis points in 2023.

The following table presents HG Global’s par value assumed, reinsurance premiums and pricing for the years ended December 31, 2024 and 2023:

*$ in Millions*

| Par value assumed: | Year Ended December 31, 2024 | 2023 |
| --- | ---: | ---: |
| Par value of primary market policies assumed (1) | $2,614.0 | $1,929.9 |
| Par value of secondary market policies assumed (1) | 338.4 | 426.4 |
| Total par value of policies assumed | $2,952.4 | $2,356.3 |
| Reinsurance premiums: |  |  |
| Gross written premiums from primary market | $36.7 | $31.6 |
| Gross written premiums from secondary market | 15.7 | 18.5 |
| Total gross written premiums | 52.4 | 50.1 |
| Ceding commission paid | 15.4 | 15.2 |
| Total gross written premiums net of ceding commission paid | $37.0 | $34.9 |
| Earned premiums | $28.9 | $26.0 |
| Pricing: |  |  |
| Gross pricing from primary market | 140 bps | 164 bps |
| Gross pricing from secondary market | 464 bps | 434 bps |
| Total gross pricing | 177 bps | 213 bps |
| Total pricing net of ceding commission paid | 125 bps | 148 bps |

(1) For capital appreciation bonds, par is adjusted to the estimated equivalent par value for current interest paying bonds.

HG Global reported pre-tax income (loss) of $(66) million in 2024 compared to $56 million in 2023. The change in pre-tax income (loss) was driven primarily by the loss on deconsolidation of BAM of $115 million in 2024. HG Global’s results included net realized and unrealized investment gains (losses) on its fixed income portfolio of $(6) million in 2024 compared to $14 million in 2023, driven by movements in interest rates. HG Global’s results included interest income on the BAM Surplus Notes of $29 million in 2024 compared to $26 million in 2023. The increase in interest income is driven by an increase in the interest rate on the BAM Surplus Notes in 2024. See **Note 10 — “Municipal Bond Guarantee Insurance - BAM Surplus Notes”** on page F-61. HG Global’s results also included a $5 million net deferred tax benefit related to the Bermuda economic transition adjustment in 2024 compared to $17 million in 2023.

During 2024, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $30 million. Of these payments, $21 million was a repayment of principal held in the Supplemental Trust, $1 million was a payment of accrued interest held in the Supplemental Trust and $8 million was a payment of accrued interest held outside the Supplemental Trust.

During 2023, HG Global received a cash payment of principal and interest on the BAM Surplus Notes of $27 million. Of this payment, $18 million was a repayment of principal held in the Supplemental Trust, $2 million was a payment of accrued interest held in the Supplemental Trust and $7 million was a payment of accrued interest held outside the Supplemental Trust.

During 2024, HG Re received a distribution out of the Supplemental Trust of $80 million, which was comprised of the assignment of $59 million of accrued interest on the BAM Surplus Notes and a cash distribution of $21 million. During 2023, HG Re did not receive any distributions out of the Supplemental Trust.

### HG Global Balance Sheets

The following tables present amounts for the HG Global segment that are presented within White Mountains’s consolidated balance sheet as of December 31, 2025 and 2024:

| Millions Assets | December 31, 2025 | 2024 |
| --- | ---: | ---: |
| Fixed maturity investments, at fair value | **$693.4** | $612.1 |
| Short-term investments, at fair value | **90.8** | 55.5 |
| Total investments | **784.2** | 667.6 |
| Cash | **.1** | 11.5 |
| BAM Surplus Notes, at fair value (1) | **339.0** | 381.7 |
| Insurance premiums receivable | **11.4** | 4.4 |
| Deferred acquisition costs | **96.9** | 86.6 |
| Other assets | **5.2** | 27.6 |
| **Total assets** | **$1,236.8** | $1,179.4 |
| **Liabilities** |  |  |
| Preferred dividends payable to White Mountains (2) | **$527.2** | $462.1 |
| Preferred dividends payable to noncontrolling interests | **16.3** | 14.2 |
| Unearned insurance premiums | **327.9** | 297.3 |
| Debt | **147.8** | 147.4 |
| Accrued incentive compensation | **1.8** | 1.4 |
| Other liabilities | **5.7** | 3.8 |
| **Total liabilities** | **1,026.7** | 926.2 |
| **Equity** |  |  |
| White Mountains’s common shareholders’ equity | **228.5** | 266.6 |
| Noncontrolling interests | **(18.4)** | (13.4) |
| **Total equity** | **210.1** | 253.2 |
| **Total liabilities and equity** | **$1,236.8** | $1,179.4 |
| **HG Global total equity after intercompany eliminations:** |  |  |
| White Mountains’s common shareholders’ equity | **$228.5** | $266.6 |
| Preferred dividends payable to White Mountains elimination (2) | **527.2** | 462.1 |
| **HG Global total equity attributable to White Mountains’s common shareholders after intercompany eliminations** | **$755.7** | $728.7 |

(1) The fair value of the BAM Surplus Notes includes accrued interest receivable.

(2) HG Global’s preferred dividends payable to White Mountains are eliminated in White Mountains’s consolidated financial statements. For segment reporting, these amounts are included within the HG Global segment and are eliminated against the offsetting receivables included within Other Operations.

### Kudu

Kudu provides capital solutions for boutique asset and wealth managers for a variety of purposes, including generational ownership transfers, management buyouts, acquisition and growth finance and legacy partner liquidity. Kudu also provides strategic advice to managers from time to time.

Kudu deployed a total of $197 million, including transaction costs, into three new asset management firms in 2025. As of December 31, 2025, Kudu had deployed a total of $1.2 billion, including transaction costs, into 30 asset and wealth management firms globally, including three that have been exited. As of December 31, 2025, the asset and wealth management firms have combined assets under management (“AUM”) of approximately $153 billion, spanning a range of asset classes, including real estate, real assets, wealth management, hedge funds, private equity and alternative credit strategies. Since inception, Kudu’s capital was deployed at an initial average gross cash yield of 9.3% based on expected cash flows in the first year following deployment.

The following table presents the components of GAAP net income (loss), EBITDA and adjusted EBITDA included in the Kudu segment for the years ended December 31, 2025, 2024 and 2023:

| Millions | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Net investment income (1) | **$78.7** | $66.7 | $71.0 |
| Net realized and unrealized investment gains (losses) | **103.5** | 51.3 | 106.1 |
| Other revenues | **1.2** | .8 | — |
| Total revenues | **183.4** | 118.8 | 177.1 |
| General and administrative expenses | **17.9** | 15.4 | 19.4 |
| Interest expense | **25.9** | 22.1 | 21.2 |
| Total expenses | **43.8** | 37.5 | 40.6 |
| GAAP pre-tax income (loss) | **139.6** | 81.3 | 136.5 |
| Income tax (expense) benefit | **(24.2)** | (16.8) | (31.9) |
| GAAP net income (loss) | **115.4** | 64.5 | 104.6 |
| Add back: |  |  |  |
| Interest expense | **25.9** | 22.1 | 21.2 |
| Income tax expense (benefit) | **24.2** | 16.8 | 31.9 |
| General and administrative expenses – depreciation | **.2** | .1 | .1 |
| Amortization of other intangible assets | **.3** | .3 | .3 |
| EBITDA (2) | **166.0** | 103.8 | 158.1 |
| Exclude: |  |  |  |
| Net realized and unrealized investment (gains) losses | **(103.5)** | (51.3) | (106.1) |
| Non-cash equity-based compensation expense | **.5** | .3 | 1.0 |
| Transaction expenses | **1.9** | 1.7 | 3.5 |
| Adjusted EBITDA (2) | **$64.9** | $54.5 | $56.5 |

(1) Net investment income includes revenues from Participation Contracts and income from short-term and other long-term investments.

(2) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

The following table presents the changes to the fair value of Kudu’s Participation Contracts for the years ended December 31, 2025 and 2024:

| Millions | December 31, 2025 | 2024 |
| --- | ---: | ---: |
| Beginning balance of Kudu’s Participation Contracts (1) | **$1,008.4** | $890.5 |
| Contributions to Participation Contracts (2) | **201.7** | 103.5 |
| Proceeds from Participation Contracts sold (2) (3) | **(28.2)** | (37.5) |
| Net realized and unrealized investment gains (losses) on Participation Contracts sold and pending sale (4) | **7.6** | (6.3) |
| Net unrealized investment gains (losses) on Participation Contracts - all other (5) | **95.5** | 58.2 |
| Ending balance of Kudu’s Participation Contracts (1) | **$1,285.0** | $1,008.4 |

(1) As of December 31, 2025, 2024 and 2023, Kudu’s other long-term investments also include $6.4, $5.6 and $5.8 related to a private debt instrument.

(2) Includes $6.6 of non-cash contributions to (proceeds from) Participation Contracts for the year ended December 31, 2025.

(3) Includes $28.1 of proceeds receivable from Participation Contracts sold during the year ended December 31, 2024.

(4) Includes net realized and unrealized investment gains (losses) recognized from Participation Contracts beginning in the quarter a contract is classified as pending sale.

(5) Includes net unrealized investment gains (losses) recognized from (i) ongoing Participation Contracts and (ii) Participation Contracts prior to classification as pending sale.

### Kudu Results — Year Ended December 31, 2025 versus Year Ended December 31, 2024

Kudu reported total revenues of $183 million, pre-tax income of $140 million and adjusted EBITDA of $65 million in 2025 compared to total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024.

Total revenues, pre-tax income and adjusted EBITDA included $79 million of net investment income in 2025 compared to $67 million in 2024. The increase in net investment income was driven primarily by amounts earned from new deployments that Kudu made in 2024 and 2025. Total revenues and pre-tax income also included $104 million of net realized and unrealized investment gains in 2025 compared to $51 million in 2024. Net realized and unrealized investment gains in 2025 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and foreign currency exchange gains from a weakening U.S. dollar. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction.

### Kudu Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

Kudu reported total revenues of $119 million, pre-tax income of $81 million and adjusted EBITDA of $55 million in 2024 compared to total revenues of $177 million, pre-tax income of $137 million and adjusted EBITDA of $57 million in 2023.

Total revenues, pre-tax income and adjusted EBITDA included $67 million of net investment income in 2024 compared to $71 million in 2023. The decrease in net investment income was driven primarily by a $12 million realization of carried

interest for one of Kudu’s Participation Contracts in 2023, partially offset by amounts earned from new deployments that Kudu made during 2023 and 2024. Total revenues and pre-tax income also included $51 million of net realized and unrealized investment gains in 2024 compared to $106 million in 2023. Net realized and unrealized investment gains in 2024 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to growth in assets under management at several managers and lower discount rates across the portfolio, partially offset by foreign currency exchange losses resulting from a strengthening U.S. dollar and an unrealized loss from a publicly listed security received by Kudu in a prior sales transaction. Net realized and unrealized investment gains in 2023 were driven by an increase in the fair value of Kudu’s Participation Contracts, primarily due to a step-up in valuation related to a pending transaction, lower discount rates across the portfolio and growth in assets under management at several managers.

### Bamboo

On January 2, 2024, White Mountains acquired a controlling interest in Bamboo.

On December 5, 2025, White Mountains completed the Bamboo Sale Transaction. As a result, White Mountains deconsolidated the Bamboo Group on December 5, 2025, and Bamboo is no longer a reportable segment. Through December 5, 2025, Bamboo’s results of operations are presented within the Bamboo segment. White Mountains’s noncontrolling equity interest in the Bamboo SPV is accounted for at fair value in other long-term investments within Other Operations. See **Note 2 — “Significant Transactions”** on page F-19.

Bamboo is a capital-light, tech- and data-enabled insurance distribution platform providing homeowners’ insurance and related products to the residential property market in California and, beginning in the third quarter of 2025, in Texas. Bamboo operates primarily through Bamboo MGA, its full-service MGA business, where the company manages all aspects of the placement process on behalf of its Capacity Providers, including product development, marketing, underwriting, policy issuance and claims oversight, and it earns commissions based on the volume and profitability of the insurance that it places.

The following table presents the components of GAAP net income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA included in White Mountains’s Bamboo segment for the period from January 1, 2025 to December 5, 2025 and for the year ended December 31, 2024:

| Millions | January 1, 2025 - December 5, 2025 | Year Ended December 31, 2024 |
| --- | ---: | ---: |
| Commission and fee revenues | **$211.4** | $134.6 |
| Earned insurance premiums | **26.7** | 39.4 |
| Other revenues | **8.2** | 5.8 |
| Total revenues | **246.3** | 179.8 |
| Broker commission expenses | **72.0** | 51.3 |
| Loss and LAE | **18.0** | 20.6 |
| Acquisition expenses | **9.7** | 14.1 |
| General and administrative expenses | **96.8** | 61.1 |
| Interest expense | **9.7** | — |
| Total expenses | **206.2** | 147.1 |
| GAAP pre-tax income (loss) | **40.1** | 32.7 |
| Income tax (expense) benefit | **(12.0)** | (6.9) |
| GAAP net income (loss) | **28.1** | 25.8 |
| Exclude: |  |  |
| Net (income) loss, Bamboo Captive | **1.0** | (1.0) |
| MGA net income (loss) (1) | **29.1** | 24.8 |
| Add back: |  |  |
| Interest expense | **9.7** | — |
| Income tax expense (benefit) | **12.0** | 6.9 |
| Depreciation expense | **1.4** | .3 |
| Amortization of other intangible assets | **12.0** | 16.4 |
| MGA EBITDA (1) | **64.2** | 48.4 |
| Exclude: |  |  |
| Non-cash equity-based compensation expense | **19.8** | 1.6 |
| Software implementation expenses | **4.3** | 1.9 |
| Restructuring expenses | **2.3** | .8 |
| Transaction expenses | **.8** | — |
| MGA adjusted EBITDA (1) | **$91.4** | $52.7 |

(1) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

### Bamboo Results—Period ended December 5, 2025 versus Year Ended December 31, 2024

Bamboo reported commission and fee revenues of $211 million and pre-tax income of $40 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported commission and fee revenues of $135 million and pre-tax income of $33 million for the year ended December 31, 2024. Bamboo reported MGA pre-tax income of $41 million and MGA adjusted EBITDA of $91 million for the period from January 1, 2025 to December 5, 2025, while Bamboo reported MGA pre-tax income of $32 million and MGA adjusted EBITDA of $53 million for the year ended December 31, 2024.

### Managed Premiums

Managed premiums represent the total premiums placed by Bamboo during the period. Managed premiums were $705 million for the period from January 1, 2025 to December 5, 2025 and $484 million for the year ended December 31, 2024. The increase in managed premiums was driven by growth in the renewal book as well as new business volume.

The following table presents Bamboo’s managed premiums for the years ended December 31, 2025, 2024 and 2023, which includes periods prior to White Mountains’s ownership of Bamboo and subsequent to the deconsolidation of Bamboo. White Mountains believes this information is useful in understanding the overall growth in Bamboo’s premium base.

| Millions | Year Ended December 31, 2025 (1) | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| New | **$298.9** | $301.5 | $146.4 |
| Net renewals, endorsements, reinstatements and cancellations | **466.9** | 182.6 | 68.6 |
| Total Managed Premiums | **$765.8** | $484.1 | $215.0 |

(1) Total managed premiums were $705.2 for the period from January 1, 2025 to December 5, 2025, including $271.7 related to new

business and $433.5 related to net renewals, endorsements, reinstatements and cancellations.

On September 2, 2025, White Mountains acquired a controlling financial interest in Distinguished. White Mountains funded the Distinguished Transaction through a combination of cash on hand and new borrowings by Distinguished. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction. The consideration is subject to customary purchase price adjustments. At closing, White Mountains owned 55.5%, inclusive of its 1.7% previously-held interest, of Distinguished on a basic units outstanding basis (43.6% on a fully-diluted/ fully-converted basis, taking account of management’s equity incentives), while Distinguished management owned 4.2% of the basic units outstanding (24.7% on a fully-diluted/fully-converted basis). See **Note 2 — “Significant Transactions”** on page F-19.

Distinguished is a full-service MGA and program administrator for specialty property and casualty insurance. Distinguished places insurance across a diversified portfolio of programs broadly grouped into two verticals. The ScaleCo vertical consists of established programs, primarily focused on real estate and hospitality end markets. The GrowthCo vertical consists of start-up programs, focused on a diversified set of specialty property and casualty insurance products across multiple industries. On behalf of its insurance carrier partners, Distinguished typically manages all aspects of the placement process, including product development, marketing, underwriting and policy issuance. Distinguished earns commissions based on the volume and profitability of the insurance that it places. Distinguished does not retain insurance risk.

The following table presents the components of GAAP net income (loss), ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA included in White Mountains’s Distinguished segment for the period from September 2, 2025, the date of acquisition, through December 31, 2025:

| Millions | September 2, 2025 - December 31, 2025 |
| --- | ---: |
| Commission and fee revenues | **$56.7** |
| Other revenues | **1.0** |
| Total revenues | **57.7** |
| Broker commission expenses | **22.1** |
| General and administrative expenses | **47.0** |
| Interest expense | **5.1** |
| Total expenses | **74.2** |
| GAAP pre-tax income (loss) | **(16.5)** |
| Income tax (expense) benefit | **2.6** |
| GAAP net income (loss) | **(13.9)** |
| Exclude: |  |
| Net (income) loss, GrowthCo | **9.8** |
| ScaleCo net income (loss) (1) | **(4.1)** |
| Add back: |  |
| Interest expense | **5.1** |
| Income tax expense (benefit) | **(2.6)** |
| Depreciation expense | **.2** |
| Amortization of other intangible assets | **7.8** |
| ScaleCo EBITDA (1) | **6.4** |
| Exclude: |  |
| Non-cash equity-based compensation expense | **2.2** |
| Transaction expenses | **.5** |
| ScaleCo adjusted EBITDA (1) | **$9.1** |

(1) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

### Distinguished Results – Period from September 2, 2025 through December 31, 2025

Distinguished reported commission and fee revenues of $57 million, pre-tax loss of $17 million and ScaleCo adjusted EBITDA of $9 million for the period from September 2, 2025 through December 31, 2025.

#### Managed Premiums and Commission and Fee Revenues

Managed premiums, which represent the total premiums placed by Distinguished, were $188 million for the period from September 2, 2025 through December 31, 2025. The following table presents Distinguished’s managed premiums and commission and fee revenues by vertical for the period from September 2, 2025 through December 31, 2025.

| Millions | September 2, 2025 - December 31, 2025 Managed Premiums | Commission and Fee Revenues |
| --- | ---: | ---: |
| ScaleCo | **$141.1** | **$41.3** |
| GrowthCo | **46.8** | **15.4** |
| Total | **$187.9** | **$56.7** |

For the year ended December 31, 2025, Distinguished’s total managed premiums were $568 million, which increased 6% compared to the year ended December 31, 2024. This includes periods prior to White Mountains’s ownership of Distinguished, which White Mountains believes is useful in understanding the overall size and growth in Distinguished’s premium base.

### Other Operations

On December 5, 2025, White Mountains closed the Bamboo Sale Transaction. White Mountains received net cash proceeds at closing of $848 million and retained an indirect equity interest valued at $250 million. White Mountains’s indirect equity interest is held through the Bamboo SPV. White Mountains’s Other Operations recognized a net gain of $816 million, which was comprised of an $849 million net gain on sale of the Bamboo Group, partially offset by $33 million of parent company compensation costs recorded within general and administrative expenses. See **Note 2 — “Significant Transactions”** on page F-19.

The following table presents the components of pre-tax income (loss) included in White Mountains’s Other Operations for the years ended December 31, 2025, 2024 and 2023:

| Millions | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Earned insurance premiums | **$22.2** | $32.7 | $— |
| Net investment income | **32.1** | 35.6 | 30.1 |
| Net realized and unrealized investment gains (losses) | **80.0** | 57.0 | 188.5 |
| Net realized and unrealized investment gains (losses) from investment in MediaAlpha | **29.6** | 38.0 | 27.1 |
| Commission and fee revenues | **16.4** | 14.8 | 13.2 |
| Net gain on sale of the Bamboo Group | **849.3** | — | — |
| Other revenues | **200.6** | 56.8 | 80.5 |
| Total revenues | **1,230.2** | 234.9 | 339.4 |
| Loss and LAE | **20.0** | 12.1 | — |
| Acquisition expenses | **8.3** | 12.1 | — |
| Cost of sales | **151.8** | 29.6 | 40.4 |
| General and administrative expenses | **236.7** | 169.5 | 182.3 |
| Interest expense | **3.2** | 2.5 | 3.7 |
| Total expenses | **420.0** | 225.8 | 226.4 |
| Pre-tax income (loss) | **$810.2** | $9.1 | $113.0 |

### Other Operations Results—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains’s Other Operations reported pre-tax income of $810 million in 2025 compared to $9 million in 2024. Results in 2025 were driven primarily by the Bamboo Sale Transaction, which resulted in a net gain of $816 million, including the impact of parent company compensation costs recorded within general and administrative expenses. White Mountains’s Other Operations reported unrealized investment gains from its investment in MediaAlpha of $30 million in 2025 compared to net realized and unrealized investment gains of $38 million in 2024. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $80 million in 2025 compared to $57 million in 2024. The increase in net realized and unrealized investment gains was driven primarily by higher gains from other long-term investments in 2025 compared to 2024. White Mountains’s Other Operations reported net investment income of $32 million in 2025 compared to $36 million in 2024. See “**Summary of Investment Results”** on page 74.

White Mountains’s Other Operations reported $201 million of other revenues in 2025 compared to $57 million in 2024. White Mountains’s Other Operations reported $152 million of cost of sales in 2025 compared to $30 million in 2024. The increases in other revenues and cost of sales were driven primarily by the acquisition of Enterprise Solutions by WTM Partners in 2025.

White Mountains’s Other Operations reported general and administrative expenses of $237 million in 2025 compared to $170 million in 2024. The increase in general and administrative expenses was driven primarily by higher incentive compensation costs, largely in connection with the Bamboo Sale Transaction, higher transaction costs and the consolidation of Enterprise Solutions. General and administrative expenses included $120 million of parent company compensation and benefits in 2025 compared to $92 million in 2024.

The Bamboo CRVs reported $5 million of pre-tax loss in 2025 compared to $9 million of pre-tax income in 2024. The Bamboo CRVs’ results included earned premiums of $22 million, loss and LAE of $20 million and acquisition expenses of $8 million in 2025 compared to earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million in 2024. Loss and LAE in 2025 included approximately $12 million related to the January 2025 California wildfires.

#### Share Repurchases

In the year ended December 31, 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million at an average share price of $2,013.67, or 92% of White Mountains’s book value per share as of December 31, 2025. This included 64,064 shares repurchased through the self-tender offer in December.

### Other Operations Results—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains’s Other Operations reported pre-tax income of $9 million in 2024 compared to $113 million in 2023. White Mountains’s Other Operations reported net realized and unrealized investment gains from its investment in MediaAlpha of $38 million in 2024 compared to unrealized investment gains of $27 million in 2023. Excluding MediaAlpha, White Mountains’s Other Operations reported net realized and unrealized investment gains of $57 million in 2024 compared to $189 million in 2023. The decrease in net realized and unrealized investment gains was driven primarily by lower unrealized gains from other long-term investments in 2024 compared to 2023. White Mountains’s Other Operations reported net investment income of $36 million in 2024 compared to $30 million in 2023. See “**Summary of Investment Results”** on page 74.

White Mountains’s Other Operations reported $57 million of other revenues in 2024 compared to $81 million in 2023. White Mountains’s Other Operations reported $30 million of cost of sales in 2024 compared to $40 million in 2023. The decreases in other revenues and cost of sales were driven primarily by a business sold within Other Operations in 2023.

White Mountains’s Other Operations reported general and administrative expenses of $170 million in 2024 compared to $182 million in 2023. General and administrative expenses included $92 million of parent company compensation and benefits in 2024 compared to $94 million in 2023.

White Mountains’s Other Operations reported $9 million of pre-tax income in 2024 related to the Bamboo CRV that incepted on April 1, 2024. The Bamboo CRV’s results included earned premiums of $33 million, loss and LAE of $12 million and acquisition expenses of $12 million.

#### Share Repurchases

In the year ended December 31, 2024, White Mountains repurchased and retired 5,269 of its common shares for $8 million at an average share price of $1,505.01.

### II. Summary of Investment Results

White Mountains’s total investment results include results from all segments. For purposes of discussing rates of return, percentages are presented gross of management fees and trading expenses.

Effective December 5, 2025, White Mountains no longer consolidates Bamboo. Through December 5, 2025, White Mountains’s consolidated financial statements included Bamboo’s investment results. Effective July 1, 2024, White Mountains no longer consolidates BAM. Through June 30, 2024, White Mountains’s consolidated financial statements included BAM’s investment results. See **Note 2 — “Significant Transactions”** on page F-19.

### Gross Investment Returns and Benchmark Returns

The following table presents the pre-tax time-weighted investment returns for White Mountains’s consolidated portfolio for the years ended December 31, 2025, 2024 and 2023:

|  | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Fixed income investments | **5.9%** | 4.3% | 5.8% |
| Bloomberg U.S. Intermediate Aggregate Index | **7.5%** | 2.5% | 5.2% |
| Common equity securities | **10.6%** | 11.3% | 13.4% |
| Investment in MediaAlpha | **14.7%** | (0.9)% | 11.8% |
| Other long-term investments | **13.2%** | 8.9% | 20.6% |
| Total common equity securities, investment in MediaAlpha and other long-term investments | **13.1%** | 10.0% | 18.5% |
| Total common equity securities and other long-term investments | **13.0%** | 9.4% | 19.0% |
| S&P 500 Index (total return) | **17.9%** | 25.0% | 26.3% |
| Total consolidated portfolio | **9.1%** | 6.9% | 11.4% |
| Total consolidated portfolio - excluding MediaAlpha (1) | **8.9%** | 6.5% | 11.4% |

(1) See “**NON-GAAP FINANCIAL MEASURES”** on page 85.

### Investment Returns—Year Ended December 31, 2025 versus Year Ended December 31, 2024

White Mountains’s total consolidated portfolio return on invested assets was 9.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 8.9% in 2025. Excluding MediaAlpha, investment returns in 2025 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net realized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of

net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the

total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024

were driven primarily by net investment income and net realized and unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

#### Fixed Income Results

White Mountains’s fixed income portfolio, including short-term investments, totaled $4.7 billion and $3.5 billion as of December 31, 2025 and 2024, which represented 56% and 54% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.5 years and 1.9 years as of December 31, 2025 and 2024. The change in the fair value and duration was driven primarily by cash inflows into the fixed income portfolio, principally related to the proceeds from the Bamboo Sale Transaction. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See **Note 3 — “Investment Securities”** on page F-23.

White Mountains’s fixed income portfolio returned 5.9% in 2025 compared to 4.3% in 2024, underperforming and outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 7.5% and 2.5% for the comparable periods. Results in 2025 were driven primarily by net investment income and White Mountains’s short duration positioning as interest rates declined in the period. Results in 2024 were driven primarily by net investment income.

#### Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.7 billion and $3.0 billion as of December 31, 2025 and 2024, which represented 44% and 46% of total invested assets. The change was driven primarily by increased exposure to other long-term investments, principally due to investments in new unconsolidated equities and an increase in the fair value of Kudu’s Participation Contracts. See **Note 3 — “Investment Securities”** on page F-23.

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 13.1% in 2025, which included $30 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 13.0% in 2025. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024.

White Mountains’s portfolio of common equity securities generally consists of international listed equity funds, primarily held at Ark, and passive ETFs. White Mountains’s ETFs seek to provide investment results generally corresponding to the performance of the S&P 500 Index. White Mountains’s portfolio of common equity securities was $483 million and $650 million as of December 31, 2025 and 2024. The decrease in common equity securities in 2025 was due to the sale of White Mountains’s ETF portfolio in the first half of 2025 to fund planned capital deployments. See **Note 2 — “Significant Transactions”** on page F-19. Subsequent to the Bamboo Sale Transaction, White Mountains began to reestablish its ETF portfolio.

White Mountains’s portfolio of common equity securities returned 10.6% in 2025 compared to 11.3% in 2024, underperforming the S&P 500 Index returns of 17.9% and 25.0% for the comparable periods. The underperformance in each period was driven primarily by certain international listed equity funds that employ a market neutral strategy. In 2025, the underperformance was also attributable to the sale of White Mountains’s ETF portfolio in the first half of the year.

White Mountains maintains a portfolio of other long-term investments that consists primarily of unconsolidated entities, including Kudu’s Participation Contracts, the Bamboo SPV, PassportCard/DavidShield and the BroadStreet SPV, as well as private equity funds and hedge funds, a bank loan fund and Lloyd’s trust deposits. White Mountains’s portfolio of other long-term investments totaled $3.0 billion and $2.2 billion as of December 31, 2025 and 2024.

White Mountains’s portfolio of other long-term investments returned 13.2% in 2025 compared to 8.9% in 2024. Returns for 2025 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net investment income and net realized and unrealized investment gains from certain unconsolidated entities, private equity funds and hedge funds. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds.

### Investment Returns—Year Ended December 31, 2024 versus Year Ended December 31, 2023

White Mountains’s total consolidated portfolio return on invested assets was 6.9% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, the total consolidated portfolio return on invested assets was 6.5% in 2024. Excluding MediaAlpha, investment returns in 2024 were driven primarily by net investment income and net unrealized investment gains from other long-term investments, net investment income from the fixed income portfolio and net unrealized gains from common equity securities.

White Mountains’s total consolidated portfolio return on invested assets, both including and excluding White Mountains’s investment in MediaAlpha, was 11.4% in 2023. The total consolidated portfolio return included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. Excluding MediaAlpha, investment returns in 2023 were driven primarily by net investment income and net realized and unrealized investment gains from the other long-term investments and fixed income portfolios.

#### Fixed Income Results

White Mountains’s fixed income portfolio, including short-term investments, totaled $3.5 billion and $3.6 billion as of December 31, 2024 and 2023, which represented 54% and 56% of total invested assets. The duration of White Mountains’s fixed income portfolio, including short-term investments, was 1.9 years as of both December 31, 2024 and 2023. White Mountains’s fixed income portfolio includes fixed maturity and short-term investments held on deposit or as collateral. See **Note 3 — “Investment Securities”** on page F-23.

White Mountains’s fixed income portfolio returned 4.3% in 2024 compared to 5.8% in 2023, outperforming the Bloomberg U.S. Intermediate Aggregate Index returns of 2.5% and 5.2% for the comparable periods. Results in 2024 were driven primarily by net investment income. Results in 2023 were driven primarily by net investment income and net unrealized investment gains as shorter-term interest rates declined marginally in the period.

#### Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Results

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments totaled $3.0 billion and $2.8 billion as of December 31, 2024 and 2023, which represented 46% and 44% of total invested assets. See **Note 3 — “Investment Securities”** on page F-23.

White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 10.0% in 2024, which included $38 million of net realized and unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 9.4% in 2024. White Mountains’s portfolio of common equity securities, its investment in MediaAlpha and other long-term investments returned 18.5% in 2023, which included $27 million of unrealized investment gains from White Mountains’s investment in MediaAlpha. White Mountains’s portfolio of common equity securities and other long-term investments returned 19.0% in 2023.

White Mountains’s portfolio of common equity securities was $650 million and $538 million as of December 31, 2024 and 2023. White Mountains’s portfolio of common equity securities returned 11.3% in 2024 compared to 13.4% in 2023, underperforming the S&P 500 Index returns of 25.0% and 26.3% for the comparable periods. The underperformance in 2024 and 2023 was driven primarily by certain international listed equity funds that employ a market neutral strategy.

White Mountains’s portfolio of other long-term investments totaled $2.2 billion and $2.0 billion as of December 31, 2024 and 2023. White Mountains’s portfolio of other long-term investments returned 8.9% in 2024 compared to 20.6% in 2023. Returns for 2024 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, as well as net unrealized investment gains from a bank loan fund and ILS funds. Returns for 2023 were driven primarily by net investment income and net realized and unrealized investment gains from Kudu’s Participation Contracts, net realized and unrealized investment gains from private equity funds, hedge funds and unconsolidated entities, as well as net investment income and unrealized gains from ILS funds.

### Portfolio Composition

The following table presents the composition of White Mountains’s total investment portfolio as of December 31, 2025 and 2024:

*$ in Millions*

|  | December 31, 2025 Carrying Value | % of Total | December 31, 2024 Carrying Value | % of Total |
| --- | ---: | ---: | ---: | ---: |
| Fixed maturity investments | **$2,770.5** | **33.3%** | $2,511.6 | 38.8% |
| Short-term investments | **1,881.7** | **22.6** | 964.2 | 14.9 |
| Common equity securities | **483.0** | **5.8** | 650.0 | 10.0 |
| Investment in MediaAlpha | **231.2** | **2.8** | 201.6 | 3.1 |
| Other long-term investments | **2,958.5** | **35.5** | 2,150.2 | 33.2 |
| Total investments | **$8,324.9** | **100.0%** | $6,477.6 | 100.0% |

The following table presents the breakdown of White Mountains’s fixed maturity investments as of December 31, 2025 and 2024 by credit class, based upon issuer credit ratings provided by Standard & Poor’s, or if unrated by Standard & Poor’s, long-term obligation ratings provided by Moody’s:

*$ in Millions*

|  | December 31, 2025 Amortized Cost | % of Total | Carrying Value | % of Total |
| --- | ---: | ---: | ---: | ---: |
| U.S. government and government-sponsored entities (1) | $826.0 | 29.8% | $814.2 | 29.4% |
| AAA/Aaa | 270.2 | 9.7 | 271.9 | 9.8 |
| AA/Aa | 242.8 | 8.8 | 244.4 | 8.8 |
| A/A | 713.1 | 25.7 | 711.7 | 25.7 |
| BBB/Baa | 710.9 | 25.6 | 716.9 | 25.9 |
| BB/Ba | 3.2 | 0.1 | 3.2 | 0.1 |
| Other/not rated | 8.6 | 0.3 | 8.2 | 0.3 |
| Total fixed maturity investments | **$2,774.8** | **100.0%** | **$2,770.5** | **100.0%** |

(1) Includes mortgage-backed securities, which carry the full faith and credit guarantee of the U.S. government (i.e., GNMA) or are guaranteed by a government sponsored entity (i.e., FNMA, FHLMC).

*$ in Millions*

|  | December 31, 2024 Amortized Cost | % of Total | Carrying Value | % of Total |
| --- | ---: | ---: | ---: | ---: |
| U.S. government and government-sponsored entities (1) | $857.7 | 33.4% | $831.7 | 33.1% |
| AAA/Aaa | 154.7 | 6.0 | 154.3 | 6.1 |
| AA/Aa | 221.4 | 8.6 | 215.9 | 8.6 |
| A/A | 627.7 | 24.5 | 608.5 | 24.2 |
| BBB/Baa | 693.7 | 27.0 | 688.7 | 27.5 |
| BB/Ba | 5.5 | 0.2 | 5.4 | 0.2 |
| Other/not rated | 8.5 | 0.3 | 7.1 | 0.3 |
| Total fixed maturity investments | **$2,569.2** | **100.0%** | **$2,511.6** | **100.0%** |

(1) Includes mortgage-backed securities, which carry the full faith and credit guarantee of the U.S. government (i.e., GNMA) or are guaranteed by a government sponsored entity (i.e., FNMA, FHLMC).

The following table presents the cost or amortized cost and carrying value of White Mountains’s fixed maturity investments by contractual maturity as of December 31, 2025 and 2024. Actual maturities could differ from contractual maturities because borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.

| Millions | December 31, 2025 Cost or Amortized Cost | Carrying Value | December 31, 2024 Cost or Amortized Cost | Carrying Value |
| --- | ---: | ---: | ---: | ---: |
| Due in one year or less | $455.3 | $455.2 | $205.8 | $203.9 |
| Due after one year through five years | 1,349.8 | 1,354.1 | 1,494.5 | 1,478.7 |
| Due after five years through ten years | 199.0 | 199.3 | 206.1 | 193.2 |
| Due after ten years | 21.7 | 21.9 | 25.3 | 25.2 |
| Mortgage and asset-backed securities and collateralized loan obligations | 749.0 | 740.0 | 637.5 | 610.6 |
| Total fixed maturity investments | **$2,774.8** | **$2,770.5** | **$2,569.2** | **$2,511.6** |

77

The following table presents the composition of White Mountains’s other long-term investments portfolio as of December 31, 2025 and 2024:

*$ in Millions*

|  | December 31, 2025 Carrying Value | % of Total | December 31, 2024 Carrying Value | % of Total |
| --- | ---: | ---: | ---: | ---: |
| Kudu’s Participation Contracts | **$1,285.0** | **43.4%** | $1,008.4 | 46.9% |
| Bamboo SPV | **250.0** | **8.5** | — | — |
| PassportCard/DavidShield | **170.0** | **5.7** | 150.0 | 7.0 |
| BroadStreet SPV | **160.0** | **5.4** | — | — |
| Elementum | **35.0** | **1.2** | 35.0 | 1.6 |
| Other unconsolidated entities | **73.7** | **2.5** | 63.6 | 3.0 |
| Total unconsolidated entities | **1,973.7** |  | 1,257.0 |  |
| Private equity funds and hedge funds | **395.2** | **13.4** | 360.6 | 16.8 |
| Bank loan fund | **308.5** | **10.4** | 264.7 | 12.3 |
| Lloyd’s trust deposits | **180.4** | **6.1** | 149.9 | 7.0 |
| ILS funds | **50.1** | **1.7** | 74.0 | 3.4 |
| Private debt instruments | **16.9** | **0.6** | 14.9 | 0.7 |
| Other | **33.7** | **1.1** | 29.1 | 1.3 |
| Total other long-term investments | **$2,958.5** | **100.0%** | $2,150.2 | 100.0% |

### Foreign Currency Exposure

As of December 31, 2025, White Mountains had foreign currency exposure on $376 million of net assets, primarily related to Ark/WM Outrigger’s non-U.S. contracts, Kudu’s non-U.S. Participation Contracts and a private debt instrument, as well as certain other foreign consolidated and unconsolidated entities.

The following table presents the fair value of White Mountains’s foreign denominated net assets (liabilities) by segment as of December 31, 2025:

*$ in Millions Currency*

|  | Ark/ WM Outrigger | Kudu | Other Operations | Total Fair Value | % of Total Shareholders’ Equity |
| --- | ---: | ---: | ---: | ---: | ---: |
| CAD | $109.4 | $55.0 | $— | $164.4 | 2.7% |
| AUD | 54.4 | 76.5 | — | 130.9 | 2.1 |
| EUR | (13.8) | 64.9 | — | 51.1 | 0.8 |
| GBP | 28.6 | — | — | 28.6 | 0.5 |
| All other | — | — | 1.4 | 1.4 | — |
| Total | **$178.6** | **$196.4** | **$1.4** | **$376.4** | **6.1%** |

78

### III. Income Taxes

As of December 31, 2025, the primary jurisdictions in which the Company’s subsidiaries and branches operated and were subject to tax are Israel, Luxembourg, the United Kingdom and the United States.

On December 15, 2022, European Union Member States voted to adopt the EU Minimum Tax Directive in conformity with the OECD Pillar Two initiative. The Pillar Two initiative includes a set of model rules that are generally designed to impose a top-up tax on a large multinational enterprise group to the extent that the group is not subject to an effective tax rate of at least 15% in each jurisdiction in which the group has a consolidated affiliate or permanent establishment. The EU Minimum Tax Directive required European Union Member States to enact conforming law by December 31, 2023. The main rule of the EU Minimum Tax Directive, the IIR, was to become effective for fiscal years beginning on or after December 31, 2023, while the UTPR was to become effective for fiscal years beginning on or after December 31, 2024. The EU Minimum Tax Directive also permits European Union Member States to elect to apply a QDMTT for fiscal years beginning on or after December 31, 2023.

On July 11, 2023, the United Kingdom enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023. On March 20, 2025, the United Kingdom enacted legislation adopting the Pillar Two UTPR effective for fiscal years beginning on or after December 31, 2024. Under the legislation, the effective date of the UTPR is deferred until fiscal years beginning on or after December 31, 2029 for U.K. companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the U.K. UTPR until January 1, 2030.

On December 20, 2023, Luxembourg enacted conforming Pillar Two legislation including the IIR and QDMTT, which became effective for fiscal years beginning on or after December 31, 2023, and the UTPR, which became effective for fiscal years beginning on or after December 31, 2024. The Luxembourg Pillar Two legislation defers the effective date of the QDMTT and UTPR until fiscal years beginning on or after December 31, 2028 and 2029, respectively, for Luxembourg companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries and (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets. White Mountains expects to meet the requirements to be exempt from the Luxembourg QDMTT and UTPR until January 1, 2029 and 2030, respectively.

On December 27, 2023, Bermuda enacted a 15% corporate income tax that became effective on January 1, 2025. The Bermuda legislation defers the effective date for five years for Bermuda companies in consolidated groups that meet certain requirements. To qualify for the deferral, generally the group must (i) have consolidated affiliates and permanent establishments in six or fewer countries, (ii) have no more than €50 million of net tangible assets outside of the country where the group has the largest amount of net tangible assets and (iii) not have a consolidated Bermuda affiliate or Bermuda permanent establishment directly or indirectly owned by a parent entity that is subject to the Pillar Two IIR in any jurisdiction. White Mountains expects to meet the requirements to be exempt from the Bermuda corporate income tax until January 1, 2030.

The Bermuda legislation also provides for an optional economic transition adjustment that can decrease or increase future years’ taxable income. Under GAAP, this economic transition adjustment was required to be recorded as a deferred tax asset or liability as of December 31, 2023 if a company intended to apply the adjustment to compute its taxable income. Accordingly, White Mountains recognized a net deferred tax benefit of $68 million in 2023, of which $51 million was recognized at Ark and $17 million was recognized at HG Global. As of July 1, 2024, White Mountains no longer consolidates BAM. As a result of the deconsolidation, the BAM Surplus Notes are recorded at fair value, which resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2024. On December 11, 2025, Bermuda enacted legislation that changed the scope of assets and liabilities subject to the economic transition adjustment. This legislation resulted in the reversal of a $5 million deferred tax liability related to the economic transition adjustment, generating a $5 million deferred tax benefit in 2025.

On January 15, 2025, the OECD released administrative guidance on its Pillar Two model rules. The January 2025 OECD Administrative Guidance provides that, subject to limited exceptions, deferred tax expense attributable to deferred tax assets resulting from the introduction of a new corporate income tax after November 30, 2021 is to be excluded when assessing whether a multinational enterprise group has an effective tax rate of at least 15% in the jurisdiction that adopted the corporate income tax. Deferred tax assets associated with the economic transition adjustment recorded under the Bermuda corporate income tax are expected to be within the scope of the January 2025 OECD Administrative Guidance.

On December 17, 2025, Luxembourg enacted legislation that adopts the January 2025 OECD Administrative Guidance. Accordingly, in any future year in which the economic transition adjustment deferred tax asset is utilized, White Mountains expects to incur a top-up tax under the Luxembourg UTPR equal to the amount of the deferred tax expense for that year associated with the economic transition adjustment. Consequently, White Mountains expects to derive no economic benefit from the Bermuda economic transition adjustment and intends to opt out of the economic transition adjustment upon becoming subject to Bermuda corporate income tax. Accordingly, White Mountains recognized a deferred tax expense of $78 million in 2025 to reverse the net deferred tax asset related to the Bermuda economic transition adjustment.

On December 11, 2025, the Bermuda government enacted legislation providing certain incentives for Bermuda-based employment, training, local expenditure and community development. The incentives are based on qualifying expenditures of eligible Bermuda entities and are provided in the form of a refundable tax credit. A Bermuda entity may be eligible for the incentives regardless of whether it is subject to the Bermuda corporate income tax. For the year ended December 31, 2025, White Mountains accrued a $10 million benefit for the incentives as a reduction to general and administrative expenses.

On July 4, 2025, the U.S. enacted the OBBBA. White Mountains does not expect the OBBBA to have a material impact on its financial statements.

White Mountains reported income tax expense of $127 million in 2025 on pre-tax income of $1,329 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, income attributable to certain gains not subject to tax in Luxembourg, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $73 million net deferred tax expense related to the reversal of the Bermuda economic transition adjustment.

White Mountains reported income tax expense of $33 million in 2024 on pre-tax income of $317 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes.

White Mountains reported income tax benefit of $16 million in 2023 on pre-tax income of $565 million. The difference between White Mountains’s effective tax rate and the current U.S. statutory rate of 21% was driven primarily by income generated in jurisdictions with lower tax rates than the United States, a full valuation allowance on net deferred tax assets in certain U.S. operations (consisting of Other Operations and BAM), withholding taxes and state income taxes. The effective rate also differed from the U.S. statutory rate of 21% due to the $68 million deferred tax benefit related to the Bermuda economic transition adjustment.

### LIQUIDITY AND CAPITAL RESOURCES

### Operating Cash and Short-term Investments

### Holding Company Level

The primary sources of cash for the Company and certain of its intermediate holding companies are expected to be distributions from its insurance, reinsurance and other operating subsidiaries, net investment income, proceeds from sales, repayments and maturities of investments, borrowings from credit facilities, capital raising activities and, from time to time, proceeds from sales of operating subsidiaries. The primary uses of cash are expected to be general and administrative expenses, purchases of investments, payments to tax authorities, payments on and repurchases/retirements of debt obligations, dividend payments to holders of the Company’s common shares, distributions to noncontrolling interest holders of consolidated subsidiaries, contributions to operating subsidiaries and, from time to time, purchases of operating subsidiaries and repurchases of the Company’s common shares.

### Operating Subsidiary Level

The primary sources of cash for White Mountains’s insurance, reinsurance and other operating subsidiaries are expected to be premium and fee collections, commissions, net investment income, proceeds from sales, repayments and maturities of investments, contributions from holding companies, borrowings from credit facilities and capital raising activities. The primary uses of cash are expected to be claim payments, policy acquisition costs, general and administrative expenses, broker commission expenses, cost of sales, purchases of investments, payments to tax authorities, payments on and repurchases/retirements of debt obligations, distributions to holding companies, distributions to noncontrolling interest holders and, from time to time, purchases of operating subsidiaries.

Both internal and external forces influence White Mountains’s financial condition, results of operations and cash flows. Premium and fee collections, investment returns, claim payments and cost of sales may be impacted by changing rates of inflation and other economic conditions. Some time may lapse between the occurrence of an insured loss, the reporting of the loss to White Mountains’s insurance and reinsurance operating subsidiaries and the settlement of the liability for that loss. The exact timing of the payment of losses cannot be predicted with certainty. White Mountains’s insurance and reinsurance operating subsidiaries maintain portfolios of invested assets with varying maturities and a substantial amount of cash and short-term investments to provide adequate liquidity for the payment of claims.

Management believes that White Mountains’s cash balances, cash flows from operations and routine sales and maturities of investments are adequate to meet expected cash requirements for the foreseeable future at both a holding company and insurance, reinsurance and other operating subsidiary level.

### Dividend Capacity

Following is a description of the dividend capacity of White Mountains’s insurance and reinsurance and other operating subsidiaries:

### Ark/WM Outrigger

During any 12-month period, GAIL, a class 4 licensed Bermuda insurer, has the ability to (i) make capital distributions of up to 15% of its total statutory capital per the previous year’s statutory financial statements or (ii) make dividend payments of up to 25% of its total statutory capital and surplus per the previous year’s statutory financial statements, without prior approval of Bermuda regulatory authorities. Accordingly, GAIL will have the ability to pay a dividend of up to $425 million during 2026, which is equal to 25% of its statutory capital and surplus of $1,700 million as of December 31, 2025, subject to meeting all appropriate liquidity and solvency requirements and the filing of its December 31, 2025 statutory financial statements. During 2025, GAIL did not pay any dividends to its immediate parent.

During 2025, Ark paid a $41 million dividend to shareholders, including $30 million that was paid to White Mountains. As of December 31, 2025, Ark and its intermediate holding companies had $9 million of net unrestricted cash and short-term investments outside of its regulated and unregulated insurance and reinsurance operating subsidiaries.

WM Outrigger Re is a special purpose insurer subject to regulation and supervision by the BMA. WM Outrigger Re does not require regulatory approval to pay dividends; however, its dividend capacity is limited to amounts held outside of the collateral trust pursuant to its reinsurance agreement with GAIL. As of December 31, 2025, WM Outrigger Re had less than $1 million of net unrestricted cash held outside the collateral trust. As of December 31, 2025, WM Outrigger Re had $232 million of statutory capital and surplus and $246 million of assets held in the collateral trusts pursuant to the reinsurance agreement with GAIL. During 2025, White Mountains received a distribution of $10 million from WM Outrigger Re.

### HG Global

As of December 31, 2025, HG Global had $619 million face value of preferred shares outstanding, of which White Mountains owned 96.9%. Holders of the HG Global preferred shares are entitled to receive cumulative dividends at a fixed annual rate of 6.0% on a quarterly basis, payable when and if declared by HG Global. As of December 31, 2025, HG Global has accrued $544 million of dividends payable to holders of its preferred shares, $527 million of which is payable to White Mountains and is eliminated in consolidation. As of December 31, 2025, HG Global and its subsidiaries had $32 million of net unrestricted cash and short-term investments outside of HG Re.

HG Re is a special purpose insurer subject to regulation and supervision by the BMA. HG Re does not require regulatory approval to pay dividends; however, its dividend capacity is limited to amounts held outside of the Collateral Trusts. As of December 31, 2025, HG Re had $4 million of net unrestricted cash and short-term investments. As of December 31, 2025, HG Re had $179 million of accrued interest on the BAM Surplus Notes held outside the Collateral Trusts. As of December 31, 2025, HG Re had $732 million of statutory capital and surplus and $1,007 million of assets held in the Collateral Trusts.

HG Global has two primary sources of cash flows: (i) interest payments on the BAM Surplus Notes that are made outside the Collateral Trusts and (ii) releases of excess balances from the Collateral Trusts. During 2025, HG Global received cash payments of principal and interest on the BAM Surplus Notes totaling $35 million. Of these payments, $24 million was a repayment of principal held in the Supplemental Trust, less than $1 million was a payment of accrued interest held in the Supplemental Trust and $11 million was a payment of accrued interest held outside the Supplemental Trust. During 2025, HG Re received a distribution from the Supplemental Trust of $61 million, which consisted of an assignment of accrued interest on the BAM Surplus Notes of $30 million and a cash distribution of $31 million.

See **Note 10 — “Municipal Bond Guarantee Reinsurance”** on page F-60.

### Kudu

During 2025, Kudu distributed $15 million to unitholders, substantially all of which was paid to White Mountains. As of December 31, 2025, Kudu had $49 million of net unrestricted cash and short-term investments.

### Bamboo

During the period from January 1, 2025 through December 5, 2025, Bamboo distributed $121 million to shareholders, $87 million of which was paid to White Mountains.

For the period from September 2, 2025, the date of acquisition, through December 31, 2025, Distinguished did not make any distributions to unitholders. As of December 31, 2025, Distinguished had $40 million of net unrestricted cash and short-term investments.

### Other Operations

During 2025, White Mountains paid a $3 million common share dividend. As of December 31, 2025, the Company and its intermediate holding companies had $975 million of net unrestricted cash, short-term investments and fixed maturity investments, $231 million of MediaAlpha common stock, $31 million of common equity securities and $294 million of private equity and hedge funds, ILS funds and certain unconsolidated entities.

During 2025, White Mountains received a distribution of $17 million from the Bamboo CRVs.

### Financing

The following table presents White Mountains’s capital structure as of December 31, 2025 and 2024:

*$ in Millions*

|  | December 31, 2025 | 2024 |
| --- | ---: | ---: |
| Ark 2021 Subordinated Notes (1) (2) | **$159.7** | $154.5 |
| HG Global Senior Notes (1) (2) | **147.8** | 147.4 |
| Kudu Credit Facility (1) (2) | **350.4** | 238.6 |
| Distinguished Credit Facility (1) (2) | **129.9** | — |
| Distinguished Other Debt (1) (2) | **10.9** | — |
| Other Operations debt (1) (2) | **38.3** | 22.0 |
| Total debt | **837.0** | 562.5 |
| Redeemable noncontrolling interests | **131.5** | — |
| Nonredeemable noncontrolling interests | **698.2** | 647.3 |
| Total White Mountains’s common shareholders’ equity | **5,425.4** | 4,483.7 |
| Total capital | **$7,092.1** | $5,693.5 |
| Total debt to total capital | **11.8%** | 9.9% |

(1) See **Note 7 — “Debt”** on page F-49 for details of debt arrangements.

(2) Net of unamortized issuance costs and original issue discount.

On July 16, 2025, the Company entered into a credit agreement, which established a senior unsecured revolving credit facility of up to $250 million that matures on July 16, 2028 (the “WTM Credit Facility”). As of December 31, 2025, the WTM Credit Facility is undrawn.

Management believes that White Mountains has the flexibility and capacity to obtain funds externally through debt or equity financing on both a short-term and long-term basis. However, White Mountains can provide no assurance that, if needed, it would be able to obtain additional debt or equity financing on satisfactory terms, if at all.

It is possible that, in the future, one or more of the rating agencies may lower White Mountains’s existing ratings. If one or more of its ratings were lowered, White Mountains could incur higher borrowing costs on future borrowings, and its ability to access the capital markets could be impacted.

### Covenant Compliance

As of December 31, 2025, White Mountains was in compliance, in all material respects, with all of the covenants under its debt instruments.

### Contractual Obligations and Commitments

The following table presents White Mountains’s material contractual obligations and commitments as of December 31, 2025:

| Millions | Due in Less Than One Year | Due in Two to Three Years | Due in Four to Five Years | Due After Five Years | Total |
| --- | ---: | ---: | ---: | ---: | ---: |
| Loss and LAE reserves (1) | $935.6 | $958.6 | $334.0 | $266.4 | $2,494.6 |
| Debt | 8.1 | 45.1 | 173.3 | 625.6 | 852.1 |
| Interest on debt | 47.3 | 123.2 | 114.4 | 232.0 | 516.9 |
| Long-term incentive compensation | 88.9 | 121.7 | 17.6 | — | 228.2 |
| Ark’s contingent consideration (2) | 328.3 | — | — | — | 328.3 |
| Redeemable noncontrolling interests (3) | — | 131.5 | — | — | 131.5 |
| Operating leases | 9.2 | 18.4 | 16.6 | 47.6 | 91.8 |
| Total contractual obligations and commitments | **$1,417.4** | **$1,398.5** | **$655.9** | **$1,171.6** | **$4,643.4** |

(1) Represents expected future cash outflows resulting from loss and LAE payments. The amounts presented are gross of reinsurance recoverables on unpaid losses of $508 as of December 31, 2025.

(2) See “***Contingent Consideration Liabilities”*** in **Note 1 — “Basis of Presentation and Significant Accounting Policies”** on page F-18.

(3) See “***Redeemable Noncontrolling Interests”*** in **Note 13 — “Common Shareholders’ Equity and Noncontrolling Interests”** on page F-68.

The long-term incentive compensation balances included in the table above include amounts payable for performance shares. Exact amounts to be paid for performance shares cannot be predicted with certainty, as the ultimate amounts of these liabilities are based on the future performance of White Mountains and the market price of the Company’s common shares at the time the payments are made.

The estimated payments reflected in the table are based on current accrual factors (including performance relative to targets and common share price) and assume that all outstanding balances were 100% vested as of December 31, 2025.

There are no provisions within White Mountains’s operating lease agreements that would trigger acceleration of future lease payments.

White Mountains does not finance its operations through the securitization of its trade receivables, through special purpose entities or through synthetic leases. Further, White Mountains has not entered into any material arrangements requiring it to guarantee payment of third-party debt or lease payments or to fund losses of an unconsolidated special purpose entity.

White Mountains also has future binding commitments to fund certain other long-term investments. These commitments, which totaled approximately $176 million as of December 31, 2025, do not have fixed funding dates and are therefore excluded from the table above.

### Share Repurchase Programs

The Company’s Board of Directors has authorized the Company to repurchase its common shares from time to time, subject to market conditions. Shares may be repurchased on the open market or through privately negotiated transactions. The repurchase authorizations do not have a stated expiration date. As of December 31, 2025, White Mountains may repurchase an additional 269,594 shares under these Board authorizations. In addition, from time to time White Mountains has also repurchased its common shares through self-tender offers that were separately authorized by its Board of Directors.

The following table presents common shares repurchased by the Company as well as the average price per share as a percent of December 31, 2025 book value per share and market value per share.

| Year Ended | Shares Repurchased | Cost (Millions) | Average Price Per Share | Average Price Per Share as % of December 31, 2025 Book Value Per Share | Average Price Per Share as % of December 31, 2025 Market Value Per Share |
| --- | ---: | ---: | ---: | ---: | ---: |
| **December 31, 2025** | **100,581** | **$202.5** | **$2,013.67** | **92%** | **97%** |
| December 31, 2024 | 5,269 | $7.9 | $1,505.01 | 69% | 72% |
|  |  |  |  | . |  |
| December 31, 2023 | 24,165 | $32.7 | $1,354.88 | 62% | 65% |

83

### Cash Flows

Detailed information concerning White Mountains’s cash flows during 2025, 2024 and 2023 follows:

### Cash flows from operations for the years ended 2025, 2024 and 2023

Net cash flows provided from operations was $551 million, $587 million and $404 million for the years ended December 31, 2025, 2024 and 2023. The decrease in cash provided from operations in 2025 was driven primarily by higher deployments at Kudu and an increase in cash outflows from Other Operations, partially offset by an increase in cash provided from operations at Ark/WM Outrigger, HG Global and Bamboo. The increase in cash provided from operations in 2024 was driven primarily by cash provided from operations at Ark/WM Outrigger Re, Kudu and Bamboo. As of December 31, 2025, the Company and its intermediate holding companies had $975 million of net unrestricted cash, short-term investments and fixed maturity investments, $231 million of MediaAlpha common stock, $31 million of common equity securities and $294 million of private equity funds and hedge funds, ILS funds and certain unconsolidated entities.

### Cash flows from investing and financing activities for the year ended December 31, 2025

#### Financing and Other Capital Activities

During 2025, the Company declared and paid a $3 million cash dividend to its common shareholders.

During 2025, White Mountains repurchased and retired 100,581 of its common shares for $203 million. The majority of these shares were repurchased through the self-tender offer that White Mountains completed in December 2025, through which it repurchased 64,064 of its common shares at a purchase price of $2,082.60 per share ($2,050.00 excluding expenses) for a total cost of approximately $133 million, including expenses. Of the shares White Mountains repurchased in 2025, 5,097 were to satisfy employee income tax withholding pursuant to employee benefit.

During 2025, HG Global received $24 million in cash payments of principal on the BAM Surplus Notes.

During 2025, Kudu borrowed $113 million in term loans under the Kudu Credit Facility.

During 2025, White Mountains contributed $76 million to Kudu, of which $15 million was used to repurchase certain management equity incentives that were then replaced with new equity incentive units.

During 2025, Bamboo borrowed $110 million in term loans under the Bamboo Credit Facility.

#### Acquisitions and Dispositions

On April 1, 2025, White Mountains closed on its acquisition of Enterprise Solutions. White Mountains paid $58 million of cash consideration, which included a post-acquisition contribution of $2 million, and Enterprise Solutions borrowed $15 million in new debt as part of the transaction.

On July 18, 2025, White Mountains deployed $150 million into BroadStreet through the BroadStreet SPV.

On September 2, 2025, White Mountains closed its acquisition of Distinguished. White Mountains paid $225 million of cash consideration, including a post-closing purchase price adjustment of $1 million. In addition, Distinguished borrowed $50 million of incremental debt and utilized $7 million of cash on hand as part of the transaction.

On December 5, 2025, White Mountains completed the Bamboo Sale Transaction for net cash proceeds at closing of $848 million.

### Cash flows from investing and financing activities for the year ended December 31, 2024

#### Financing and Other Capital Activities

During 2024, the Company declared and paid a $3 million cash dividend to its common shareholders.

During 2024, White Mountains repurchased and retired 5,269 of its common shares for $8 million, all of which were to satisfy employee income tax withholding pursuant to employee benefit plans.

During 2024, Ark repaid the outstanding balance of $30 million and extinguished the Ark 2007 Subordinated Notes.

During 2024, Kudu borrowed $35 million in term loans under the Kudu Credit Facility.

During the six months ended December 31, 2024, subsequent to BAM’s deconsolidation, HG Global received a $16 million cash payment of principal on the BAM Surplus Notes.

BAM received $26 million in MSC during the six months ended June 30, 2024, prior to its deconsolidation.

#### Acquisitions and Dispositions

On January 2, 2024, White Mountains completed the acquisition of Bamboo, investing $297 million in equity into Bamboo, which included the contribution of $36 million to retire Bamboo’s legacy credit facility and the contribution of $20 million of primary capital.

On May 10, 2024, MediaAlpha completed a secondary offering of 7.6 million shares at $19.00 per share ($18.24 per share net of underwriting fees). In the secondary offering, White Mountains sold 5.0 million shares for net proceeds of $91 million.

### Cash flows from investing and financing activities for the year ended December 31, 2023

#### Financing and Other Capital Activities

During 2023, the Company declared and paid a $3 million cash dividend to its common shareholders.

During 2023, White Mountains repurchased and retired 24,165 of its common shares for $33 million. Of the shares White Mountains repurchased in 2023, 4,629 were to satisfy employee income tax withholding pursuant to employee benefit plans.

During 2023, Kudu borrowed $12 million in term loans under the Kudu Credit Facility.

During 2023, Kudu repaid $17 million in term loans under the Kudu Credit Facility.

#### Acquisitions and Dispositions

On June 28, 2023, White Mountains completed a tender offer to purchase 5.9 million additional shares of MediaAlpha at a purchase price of $10.00 per share for a total cost of $59 million.

### TRANSACTIONS WITH RELATED PERSONS

White Mountains does not have any transactions with related persons to report as of December 31, 2025.

### NON-GAAP FINANCIAL MEASURES

This report includes 12 non-GAAP financial measures that have been reconciled from their most comparable GAAP financial measures.

### Ark’s tangible book value and tangible capital

Ark’s tangible book value is a non-GAAP financial measure derived by adjusting GAAP book value to exclude goodwill, other intangible assets, the related deferred tax liability and the contingent consideration liability. The contingent consideration liability represents the estimated fair value of the additional shares that could be earned by management rollover shareholders if and to the extent that White Mountains achieves certain MOIC return thresholds. If earned, these additional shares would result in a reallocation of economics among Ark’s shareholders, which is reflected in the fair value of the contingent consideration liability recorded by White Mountains, but would have no impact on Ark’s stand-alone book value or tangible book value. White Mountains believes that this non-GAAP financial measure is useful to management and investors in evaluating Ark’s enterprise value. See page 59 for the reconciliation of Ark’s GAAP equity to tangible book value. Ark’s tangible capital is a non-GAAP financial measure derived by adding debt to tangible book value. See page 59 for the reconciliation of Ark’s GAAP equity to tangible capital.

### Kudu’s EBITDA and adjusted EBITDA

Kudu's EBITDA and adjusted EBITDA are non-GAAP financial measures. EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to GAAP net income (loss). Adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate EBITDA. The items relate to (i) net realized and unrealized investment gains (losses) on Kudu's Participation Contracts, (ii) non-cash equity-based compensation expense and (iii) transaction expenses.

A description of each item follows:

- *Net realized and unrealized investment gains (losses)* - Represents net unrealized investment gains and losses on Kudu’s Participation Contracts, which are recorded at fair value under GAAP, and realized investment gains and losses recorded on Kudu’s Participation Contracts sold during the period.
- *Non-cash equity-based compensation expense* - Represents non-cash expenses related to Kudu’s management compensation that are settled with equity units in Kudu.
- *Transaction expenses* - Represents costs directly related to Kudu’s mergers and acquisitions activity, such as external lawyer, banker, consulting and placement agent fees, which are not capitalized and are expensed under GAAP.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Kudu’s performance. The reconciliation of Kudu’s GAAP net income (loss) to EBITDA and adjusted EBITDA is included on page 67.

### Bamboo’s MGA pre-tax income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA

Bamboo’s MGA pre-tax income (loss), MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA are non-GAAP financial measures.

MGA pre-tax income (loss) and MGA net income (loss) are non-GAAP financial measures that exclude the results of the Bamboo Captive, which is consolidated by Bamboo MGA under GAAP, from Bamboo’s consolidated GAAP pre-tax income (loss) and net income (loss). The following table presents the reconciliation from Bamboo’s consolidated GAAP pre-tax income (loss) to MGA pre-tax income (loss):

| Millions | January 1, 2025 - December 5, 2025 | Year Ended December 31, 2024 |
| --- | ---: | ---: |
| Bamboo’s consolidated GAAP pre-tax income (loss) | **$40.1** | **$32.7** |
| Remove pre-tax (income) loss, Bamboo Captive | **1.0** | **(1.0)** |
| MGA pre-tax income (loss) | **$41.1** | **$31.7** |

MGA EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to MGA net income (loss). MGA adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those added back to calculate MGA EBITDA. The items relate to (i) non-cash equity-based compensation expense, (ii) software implementation expenses, (iii) restructuring expenses and (iv) transaction expenses. A description of each item follows:

- *Non-cash equity-based compensation expense* - Represents non-cash expenses related to Bamboo’s management compensation that are settled with equity units in Bamboo.
- *Software implementation expenses* - Represents costs directly related to Bamboo’s implementation of new software.
- *Restructuring expenses* - Represents costs directly related to Bamboo’s corporate restructuring and capital planning activities.
- *Transaction expenses* - Represents costs directly related to transaction activities at Bamboo, which are not capitalized and are expensed under GAAP.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Bamboo’s performance. See page 69 for the reconciliation of Bamboo’s consolidated GAAP net income (loss) to MGA net income (loss), MGA EBITDA and MGA adjusted EBITDA.

### Distinguished’s ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA

Distinguished’s ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA are non-GAAP financial measures. ScaleCo net income (loss) is a non-GAAP financial measure that excludes the results of the GrowthCo vertical, which is consolidated under GAAP, from Distinguished’s consolidated GAAP net income (loss). ScaleCo EBITDA is a non-GAAP financial measure that adds back interest expense on debt, income tax (expense) benefit, depreciation and amortization of other intangible assets to ScaleCo net income (loss). ScaleCo adjusted EBITDA is a non-GAAP financial measure that excludes certain other items in GAAP net income (loss) in addition to those items added back to calculate ScaleCo EBITDA. The items relate to (i) non-cash equity-based compensation expense and (ii) transaction expenses. A description of each item follows:

- *Non-cash equity-based compensation expense* - Represents non-cash expenses related to Distinguished’s management compensation that are settled with equity units in Distinguished.
- *Transaction expenses* - Represents costs directly related to transaction activities at Distinguished, which are not capitalized and are expensed under GAAP.

White Mountains believes that these non-GAAP financial measures are useful to management and investors in evaluating Distinguished’s performance. White Mountains also believes that excluding the results of the GrowthCo vertical, which Distinguished views as an investment in start-up programs, is useful to understanding the performance of Distinguished’s established programs. See page 71 for the reconciliation of Distinguished’s consolidated GAAP net income (loss) to ScaleCo net income (loss), ScaleCo EBITDA and ScaleCo adjusted EBITDA.

### Total consolidated portfolio return excluding MediaAlpha

Total consolidated portfolio return excluding MediaAlpha is a non-GAAP financial measure that removes the net investment income and net realized and unrealized investment gains (losses) from White Mountains’s investment in MediaAlpha. White Mountains believes this non-GAAP measure to be useful to management and investors by showing the underlying performance of White Mountains’s investment portfolio without regard to White Mountains’s investment in MediaAlpha.

The following table presents return reconciliations from GAAP to the reported percentages:

|  | Year Ended December 31, 2025 | 2024 | 2023 |
| --- | ---: | ---: | ---: |
| Total consolidated portfolio return | **9.1%** | 6.9% | 11.4% |
| Remove MediaAlpha | **(0.2)** | (0.4) | — |
| Total consolidated portfolio return excluding MediaAlpha | **8.9%** | 6.5% | 11.4% |

### CRITICAL ACCOUNTING ESTIMATES

Management’s Discussion and Analysis of Financial Condition and Results of Operations discuss the Company’s consolidated financial statements, which have been prepared in accordance with GAAP. The financial statements presented herein include all adjustments considered necessary by management to fairly present the financial condition, results of operations and cash flows of White Mountains.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Certain of these estimates are considered critical in that they involve a higher degree of judgment and are subject to a significant degree of variability. On an ongoing basis, management evaluates its estimates and bases its estimates on historical experience and on various other factors that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources.

### 1\. Fair Value Measurements

### General

White Mountains records certain assets and liabilities at fair value in its consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants (an exit price) at a particular measurement date. Fair value measurements are categorized into a hierarchy that distinguishes between inputs based on market data from independent sources (observable inputs) and a reporting entity’s internal assumptions based upon the best information available when external market data is limited or unavailable (unobservable inputs). Quoted prices in active markets for identical assets have the highest priority (“Level 1”), followed by observable inputs other than quoted prices including prices for similar but not identical assets or liabilities (“Level 2”) and unobservable inputs, including the reporting entity’s estimates of the assumptions that market participants would use, having the lowest priority (“Level 3”).

The valuation of assets and liabilities measured at fair value requires management to make estimates and apply judgment to matters that may carry a significant degree of uncertainty. In determining its estimates of fair value, White Mountains uses a variety of valuation approaches and inputs. Whenever possible, White Mountains estimates fair value using valuation methods that maximize the use of quoted market prices or other observable inputs. Where appropriate, assets and liabilities measured at fair value have been adjusted for the effect of counterparty credit risk.

Fair value estimates for instruments that trade infrequently and have few or no quoted market prices or other observable inputs are classified as Level 3 measurements. The determination of the fair value of these Level 3 instruments involves significant management judgment and the use of valuation analyses and unobservable inputs that are inherently subjective and uncertain. These unobservable inputs reflect White Mountains’s assumptions of what market participants would use in valuing the instrument. See Item 1A. Risk Factors, “***Our investment portfolio includes securities that do not have readily observable market prices. We use valuation methodologies that are inherently subjective and uncertain to value these securities. The values of securities established using these methodologies may never be realized, which could materially adversely affect our results of operations and financial condition.”*** on page 36.

See **Note 1 — “Basis of Presentation and Significant Accounting Policies”** on page F-8 for White Mountains’s accounting policies for investment securities.

As of December 31, 2025, White Mountains’s most significant assets classified as Level 3 measurements include the BAM Surplus Notes, Kudu’s Participation Contracts, the Bamboo SPV and PassportCard/DavidShield. As of December 31, 2025, the Bamboo SPV was measured at fair value based on the value implied in the Bamboo Sale Transaction. See **Note 2 — “Significant Transactions”** on page F-19.

### BAM Surplus Notes

As of December 31, 2025, the fair value of the BAM Surplus Notes was $339 million. On a quarterly basis, White Mountains values the BAM Surplus Notes using a discounted cash flow analysis. The discounted cash flow analysis used to fair value the BAM Surplus Notes depends on key inputs, such as projections of future revenues and earnings for BAM, expected payments on the BAM Surplus Notes through maturity and a discount rate to reflect time value and related uncertainty of the repayment pattern. The expected payments on the BAM Surplus Notes are based on management judgment, considering current performance, budgets and projected future results. These expected payments depend on BAM’s ability to generate excess cash flows from its operations, driven primarily by assumptions regarding future trends for the issuance of municipal bonds, interest rates, credit spreads, insured market penetration, competitive activity in the market for municipal bond insurance and other factors affecting the demand for and pricing of BAM’s municipal bond insurance, as well as BAM’s investment returns. The discount rate considers comparably-rated companies and instruments, adjusted for risks specific to BAM and the BAM Surplus Notes. As of December 31, 2025, White Mountains concluded that a discount rate of 8.05% was appropriate for the valuation of the BAM Surplus Notes.

When making its fair value selection, which is within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, facts and circumstances specific to BAM’s business and industry and any infrequent or unusual results for the period. See Item 1A. Risk Factors, “***We may be subject to volatility from the valuation of the BAM Surplus Notes, which could materially adversely affect our results of operations and financial condition.”*** on page 33.

With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of the BAM Surplus Notes as of December 31, 2025, resulting from changes to the discount rate used in the discounted cash flow analysis:

| Millions | Discount Rate |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: |
|  | **6.0%** | **7.0%** | **8.05%** | **9.0%** | **10.0%** |
| BAM Surplus Notes, at fair value | $398 | $369 | **$339** | $312 | $283 |

### Kudu’s Participation Contracts

As of December 31, 2025, Kudu has a portfolio of Participation Contracts with a total fair value of $1,285 million. On a quarterly basis, White Mountains fair values each of Kudu’s Participation Contracts, typically using a discounted cash flow analysis. The discounted cash flow analyses used to fair value Kudu’s Participation Contracts include key inputs, such as projections of future revenues and earnings of Kudu’s managers, a discount rate and a terminal cash flow exit multiple. The expected future cash flows are based on management judgment, considering current performance, budgets and projected future results. The discount rates reflect the weighted average cost of capital, considering comparable public company data and adjusted for risks specific to the business and industry. The terminal cash flow exit multiple is generally based on expectations of annual cash flow to Kudu from each of its managers in the terminal year of the discounted cash flow analysis. In determining fair value, White Mountains considers factors for each of Kudu’s managers, such as performance of products and vehicles, expected asset growth rates, new fund launches, fee rates by product, capacity constraints, operating cash flows and other qualitative factors, including the assessment of key personnel. The inputs to each discounted cash flow analysis vary depending on the nature of each of Kudu’s managers. As of December 31, 2025, White Mountains concluded that pre-tax discount rates in the range of 16% to 25% and terminal cash flow exit multiples in the range of 7 to 22 times were appropriate for the valuations of Kudu’s Participation Contracts.

When making its fair value selections, which are within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, including any relevant market multiples and multiples implied by recent transactions, facts and circumstances specific to Kudu’s managers and any infrequent or unusual results for the period.

With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of Kudu’s Participation Contracts as of December 31, 2025, resulting from changes in key inputs to the discounted cash flow analysis, including discount rates and terminal cash flow exit multiples:

| Millions | Discount Rate(1) |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: |
| **Terminal Cash Flow Exit Multiple** | **-2%** | **-1%** | **16% - 25%** | **+1%** | **+2%** |
| **+2** | $1,554 | $1,457 | $1,368 | $1,283 | $1,209 |
| **+1** | $1,504 | $1,412 | $1,326 | $1,245 | $1,174 |
| **7x to 22x** | $1,455 | $1,366 | **$1,285** | $1,207 | $1,139 |
| **-1** | $1,406 | $1,321 | $1,243 | $1,169 | $1,104 |
| **-2** | $1,356 | $1,276 | $1,202 | $1,136 | $1,075 |

(1) Since Kudu’s Participation Contracts are not subject to corporate taxes within Kudu Investment Management, LLC, pre-tax discount rates are applied to pre-tax cash flows in determining fair values.

### PassportCard/DavidShield

As of December 31, 2025, the fair value of White Mountains’s investment in PassportCard/DavidShield was $170 million. On a quarterly basis, White Mountains values its investment in PassportCard/DavidShield using a discounted cash flow analysis. The discounted cash flow analysis used to fair value PassportCard/DavidShield includes key inputs, such as projections of future revenues and earnings, a discount rate and a terminal revenue growth rate. The expected future cash flows are based on management judgment, considering current performance, budgets and projected future results. The discount rate reflects the weighted average cost of capital, considering comparable public company data and adjusted for risks specific to the business and industry. The terminal revenue growth rate is based on company, industry and macroeconomic expectations of perpetual revenue growth subsequent to the end of the discrete period in the discounted cash flow analysis. As of December 31, 2025, White Mountains concluded that an after-tax discount rate of 24% and a terminal revenue growth rate of 4% were appropriate for the valuation of its investment in PassportCard/DavidShield.

When making its fair value selection, which is within a range of reasonable values derived from the discounted cash flow analysis, White Mountains considers all available information, including any relevant market multiples and multiples implied by recent transactions, facts and circumstances specific to PassportCard/DavidShield’s businesses and industries and any infrequent or unusual results for the period.

With a discounted cash flow analysis, small changes to key inputs may result in significant changes to fair value. The following table presents the estimated effect on the fair value of White Mountains’s investment in PassportCard/DavidShield as of December 31, 2025, resulting from changes in key inputs to the discounted cash flow analysis, including the discount rate and terminal revenue growth rate:

| Millions | Discount Rate |  |  |  |  |
| ---: | ---: | ---: | ---: | ---: | ---: |
| **Terminal Revenue Growth Rate** | **22%** | **23%** | **24%** | **25%** | **26%** |
| **5.0%** | $200 | $186 | $173 | $162 | $152 |
| **4.0%** | $195 | $182 | **$170** | $159 | $150 |
| **3.0%** | $191 | $179 | $167 | $157 | $148 |

89

### 2\. Ark’s Loss and LAE Reserves

### General

Ark establishes loss and LAE reserves that are estimates of amounts needed to pay claims and related expenses in the future for insured events that have already occurred. The process of estimating loss and LAE reserves involves a considerable degree of judgment by management and, as of any given date, is inherently uncertain. See **Note 5 — “Loss and Loss Adjustment Expense Reserves”** on page F-36 for a description of Ark’s loss and LAE reserves and actuarial methods.

Ark performs an actuarial review of its recorded loss and LAE reserves each quarter, using several generally accepted actuarial methods to evaluate its loss reserves, each of which has its own strengths and weaknesses. Management bases its level of reliance on a particular method based on the facts and circumstances at the time the reserve estimates are made.

As part of Ark’s quarterly actuarial review, Ark compares the previous quarter’s projections of incurred, paid and case reserve activity, including amounts incurred but not reported, to actual amounts experienced in the quarter. Differences between previous estimates and actual experience are evaluated to determine whether a given actuarial method for estimating loss and LAE reserves should be relied upon to a greater or lesser extent than it had been in the past. While some variance is expected each quarter due to the inherent uncertainty in estimating loss and LAE reserves, persistent or large variances would indicate that prior assumptions and/or reliance on certain actuarial methods may need to be revised going forward.

Upon completion of each quarterly review, Ark selects indicated loss and LAE reserve levels based on the results of the relevant actuarial methods, which are the primary consideration in determining management’s best estimate of required loss and LAE reserves. However, in making its best estimate, management also considers other qualitative factors that may lead to a difference between held reserves and actuarially indicated reserve levels. Typically, these qualitative factors are considered when management and Ark’s actuaries conclude that there is insufficient historical incurred and paid loss information or that there is particular uncertainty about whether trends included in the historical incurred and paid loss information are likely to repeat in the future. Such qualitative factors include, among others, recent entry into new markets or new products, improvements in the claims department that are expected to lessen future ultimate loss costs, legal and regulatory developments, inflation, climate change or other uncertainties that may arise.

The process of establishing loss and LAE reserves, including amounts incurred but not reported, is complex and imprecise, as it must consider many variables that are subject to the outcome of future events. As a result, informed subjective estimates and judgments as to Ark’s ultimate exposure to losses are an integral component of the loss and LAE reserving process. Ark categorizes and tracks insurance and reinsurance reserves by “reserving class of business” for each underwriting office, London and Bermuda, and then aggregates the reserving classes by line of business, which are summarized herein as property and accident & health, marine & energy, specialty, casualty-active and casualty-runoff.

Ark regularly reviews the appropriateness of its loss and LAE reserves at the reserving class of business level, considering a variety of trends that impact the ultimate settlement of claims for the subsets of claims in each particular reserving class. Loss and LAE are categorized by the year in which the policy is underwritten (the year of account, or underwriting year) for purposes of Ark’s claims management and estimation of the ultimate loss and LAE reserves. For purposes of Ark’s reporting under GAAP, loss and LAE are categorized by the accident year.

### Loss and LAE Reserves by Line of Business

The following table summarizes Ark’s loss and LAE reserves, net of reinsurance recoverables on unpaid losses, as of December 31, 2025:

| Millions | December 31, 2025 Case | IBNR | Total |
| --- | ---: | ---: | ---: |
| Property and Accident & Health | $236.8 | $341.5 | $578.3 |
| Marine & Energy | 146.4 | 422.6 | 569.0 |
| Specialty | 96.8 | 411.4 | 508.2 |
| Casualty-Active | 36.0 | 194.6 | 230.6 |
| Casualty-Runoff | 28.2 | 28.9 | 57.1 |
| Total loss and LAE reserves, net of reinsurance recoverables | **$544.2** | **$1,399.0** | **$1,943.2** |

90

For loss and LAE reserves as of December 31, 2025, Ark considers that the impact of the various reserving factors, as described in **Note 5 — “Loss and Loss Adjustment Expense Reserves”** on page F-36, on future paid losses would be similar to the impact of those factors on historical paid losses.

The major causes of material uncertainty (i.e., reserving factors) generally will vary for each line of business, as well as for each separately analyzed reserving class of business within the line of business. Also, reserving factors can have offsetting or compounding effects on estimated loss and LAE reserves. In most cases, it is not possible to measure the effect of a single reserving factor and construct a meaningful sensitivity expectation. Actual results will likely vary from expectations for each of these assumptions, resulting in an ultimate claim liability that is different from that being estimated currently.

Additional causes of material uncertainty exist in most product lines and may impact the types of claims that could occur within a particular line of business or reserving class of business. Examples where reserving factors within a line of business or reserving class of business are subject to change include changing types of insureds (e.g., size of account, industry insured, jurisdiction), changing underwriting standards or changing policy provisions (e.g., deductibles, policy limits, endorsements).

### Ark Loss and LAE Development

See **Note 5 — “Loss and Loss Adjustment Expense Reserves”** on page F-36 for prior year loss and LAE development discussions for the year ended December 31, 2025.

### Range of Reserves

The following table shows the recorded loss and LAE reserves and the high and low ends of Ark’s range of reasonable loss and LAE reserve estimates, net of reinsurance recoverables on unpaid losses, as of December 31, 2025. See **Note 5 — “Loss and Loss Adjustment Expense Reserves”** on page F-36 for a description of Ark’s loss and LAE reserves and actuarial methods.

| Millions | December 31, 2025 Low | Recorded | High |
| --- | ---: | ---: | ---: |
| Total loss and LAE reserves, net of reinsurance recoverables | $1,510.2 | **$1,943.2** | $2,023.8 |

The recorded reserves represent management's best estimate of unpaid loss and LAE reserves. Management’s best estimate of reserves is in the upper portion of the actuarial range of estimates in response to potential volatility in the actuarial indications and estimates for large claims. Ark uses the results of several different standard actuarial methods to develop its best estimate of ultimate loss and LAE reserves.

On an annual basis, Ark uses an independent external actuary to provide actuarial opinions on the reasonableness of loss and LAE reserves for its operating subsidiaries. Ark uses the independent actuarial review solely to corroborate Ark’s recorded loss and LAE reserves. The result of the independent actuarial review indicated that Ark’s net recorded loss and LAE reserves fall within the range noted above.

Although Ark believes its loss and LAE reserves are reasonably stated, ultimate losses may deviate, perhaps materially, from the recorded reserve amounts and could be above the high end of the range of actuarial projections. This is because ranges are developed based on known events as of the valuation date, whereas the ultimate disposition of losses is subject to the outcome of events and circumstances that may be unknown as of the valuation date.

#### Sensitivity Analysis

Below is a discussion of possible variations from current estimates of loss and LAE reserves due to changes in certain key assumptions. Each of the impacts described below is estimated individually, without consideration for any correlation among key assumptions. Further, there is uncertainty around other assumptions not explicitly quantified in the discussion below. Therefore, it would be inappropriate to take each of the amounts described below and add them together in an attempt to estimate volatility for Ark’s reserves in total. It is important to note that the volatilities and variations discussed below are not meant to be worst-case scenarios or an all-inclusive list, and therefore it is possible that future volatilities and variations may be more than amounts discussed below.

- *Sustained elevated levels of inflation:* Elevated levels of economic inflation have been observed since 2021. While most global economies are seeing these elevated levels begin to decline, inflation continues to be a key focus point for central bank policy. The extent to which inflation will impact the ultimate cost of insurance claims remains uncertain, particularly in the casualty lines of business with key social inflation drivers being court awards, changes in technology and the legal environment. For example, a hypothetical increase in inflation rates by 4% per annum would increase the recorded loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for the casualty reserving lines of business by approximately $20 million, or approximately 7% of the recorded casualty loss and LAE reserves of $288 million.
- *Catastrophe losses:* The years 2017 through 2025 have been active for major loss events, including natural catastrophes. As time has passed, the emerging claims information for major loss events has been better than expected. As of December 31, 2025, Ark has recorded $230 million of loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for major loss events, of which $171 million is held as IBNR reserves. Some, but perhaps not all, of the IBNR reserves may be needed to handle adverse reporting from clients.
- *Conflict in Ukraine and Russia*: The conflict in Ukraine and Russia has and will continue to have a significant impact on the insurance industry. Recent U.K. High Court rulings on leasing claims provided more certainty on coverages related to aviation hull war risk claims, but there are additional court cases to be decided and there is uncertainty as to how claims will be presented to reinsurers. For the year ended December 31, 2025, Ark recognized $91 million of unfavorable loss reserve development related to aviation losses from the conflict in Ukraine and Russia, driven by the U.K. High Court rulings. This is a complex loss event that will continue to be litigated and negotiated in the future. As such, there remains uncertainty with respect to the ultimate impact to both insurers and reinsurers.

### Loss and LAE Reserve Summary

The following table summarizes the loss and LAE reserve activity of Ark’s insurance and reinsurance subsidiaries for the year ended December 31, 2025. The amounts in the table include balances ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements.

| Millions | Year Ended December 31, 2025 |
| --- | ---: |
| Gross beginning balance | $2,127.5 |
| Less: beginning reinsurance recoverable on unpaid losses | (466.2) |
| Net loss and LAE reserves | 1,661.3 |
| Loss and LAE incurred relating to: |  |
| Current year losses | 925.1 |
| Prior year losses | (106.3) |
| Net incurred loss and LAE | 818.8 |
| Loss and LAE paid relating to: |  |
| Current year losses | (187.9) |
| Prior year losses | (370.1) |
| Net paid loss and LAE | (558.0) |
| Foreign currency translation and other adjustments to loss and LAE reserves | 21.1 |
| Net ending balance | 1,943.2 |
| Plus: ending reinsurance recoverable on unpaid losses | 537.8 |
| Gross ending balance | **$2,481.0** |

During the year ended December 31, 2025, Ark experienced $106 million of net favorable prior year loss reserve development, driven primarily by the property and accident & health ($85 million) and specialty ($27 million) reserving lines of business, partially offset by net unfavorable development in the marine & energy ($5 million) and casualty-active ($4 million) reserving lines of business. For property and accident & health, the net favorable prior year loss reserve development was driven primarily by positive claims experience for the 2024 and 2023 accident years. For specialty, the net favorable prior year loss reserve development was driven primarily by positive claims experience for the 2023 accident year, partially offset by negative claims experience for the 2022 and 2024 accident years. In addition, the net favorable prior year loss reserve development for specialty includes $91 million of unfavorable development related to aviation losses from the conflict in Ukraine and Russia resulting from the 2025 U.K. High Court rulings on leasing claims.

The following table summarizes the unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses, for each of Ark’s major reserving lines of business as of December 31, 2025. The amounts in the table include balances ceded by Ark to WM Outrigger Re, which eliminate in White Mountains’s consolidated financial statements.

| Millions | As of December 31, 2025 |
| --- | ---: |
| Property and Accident & Health | $578.3 |
| Marine & Energy | 569.0 |
| Specialty | 508.2 |
| Casualty-Active | 230.6 |
| Casualty-Runoff | 57.1 |
| Unpaid loss and LAE reserves, net of reinsurance recoverables on unpaid losses | 1,943.2 |
| Plus: Reinsurance recoverables on unpaid losses |  |
| Property and Accident & Health | 171.9 |
| Marine & Energy | 208.9 |
| Specialty | 44.4 |
| Casualty-Active | 113.0 |
| Casualty-Runoff | (.4) |
| Total Reinsurance recoverables on unpaid losses | 537.8 |
| Total unpaid loss and LAE reserves | **$2,481.0** |

The following five tables cover each of Ark’s property and accident & health, marine & energy, specialty, casualty-active and casualty-runoff reserving lines of business and are net of reinsurance. Each of the five tables includes three sections as follows:

The top section of the table presents, for each of the previous ten accident years, (1) cumulative total undiscounted incurred loss and LAE as of each of the previous ten year-end evaluations, (2) total IBNR plus expected development on reported claims as of December 31, 2025 and (3) the cumulative number of reported claims as of December 31, 2025.

The middle section of the table presents cumulative paid loss and LAE for each of the previous ten accident years as of each of the previous ten year-end evaluations. Also included in this section is a calculation of the loss and LAE reserves as of December 31, 2025, which is then included in the reconciliation to the consolidated balance sheet presented above. The total unpaid loss and LAE reserves as of December 31, 2025 is calculated as the cumulative incurred loss and LAE from the top section less the cumulative paid loss and LAE from the middle section, plus any outstanding liabilities from accident years prior to 2015.

The bottom section of the table is supplementary information about the average historical claims duration as of December 31, 2025. It shows the weighted average annual percentage payout of incurred loss and LAE by accident year as of each age. For example, the first column is calculated as the incremental paid loss and LAE in the first calendar year for each given accident year (e.g., calendar year 2025 for accident year 2025, calendar year 2024 for accident year 2024) divided by the cumulative incurred loss and LAE as of December 31, 2025 for that accident year. The resulting ratios are weighted using cumulative incurred loss and LAE as of December 31, 2025.

*$ in Millions*

| Property and Accident & Health Accident Year | Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | As of December 31, 2025 Total IBNR plus expected development on reported claims | Cumulative number of reported claims |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 2016 | $22.7 | $17.8 | $18.6 | $18.7 | $18.7 | $18.9 | $18.8 | $18.8 | $18.8 | $18.8 | $.2 | 3,434 |
| 2017 |  | 31.6 | 38.3 | 45.8 | 44.8 | 43.4 | 42.9 | 44.3 | 43.9 | 43.3 | 15.6 | 4,629 |
| 2018 |  |  | 41.4 | 47.8 | 49.7 | 47.4 | 47.4 | 47.0 | 47.0 | 49.0 | 2.7 | 4,293 |
| 2019 |  |  |  | 34.6 | 31.7 | 27.4 | 24.2 | 23.5 | 23.2 | 21.5 | .5 | 4,030 |
| 2020 |  |  |  |  | 78.1 | 76.3 | 75.3 | 79.1 | 81.0 | 84.8 | 6.0 | 4,664 |
| 2021 |  |  |  |  |  | 173.0 | 156.8 | 168.9 | 171.5 | 169.7 | 8.1 | 3,533 |
| 2022 |  |  |  |  |  |  | 245.7 | 269.6 | 280.0 | 281.9 | 9.0 | 4,100 |
| 2023 |  |  |  |  |  |  |  | 216.9 | 178.6 | 130.4 | 20.8 | 3,688 |
| 2024 |  |  |  |  |  |  |  |  | 364.8 | 324.6 | 106.4 | 4,495 |
| 2025 |  |  |  |  |  |  |  |  |  | 394.1 | 171.7 | 3,899 |
|  |  |  |  |  |  |  |  |  | Total | **$1,518.1** |  |  |

| Property and Accident & Health Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 | 2025 |
| --- | ---: |
| 2016 $8.6 $13.3 $16.6 $17.0 $17.1 $17.4 $18.0 $18.2 $18.4 | $18.4 |
| 2017 17.0 26.1 31.9 33.1 29.9 27.7 25.9 28.7 | 29.3 |
| 2018 15.8 32.7 40.6 40.6 41.4 43.4 44.2 | 45.2 |
| 2019 6.9 17.0 18.6 18.8 19.6 20.9 | 19.9 |
| 2020 11.4 34.5 47.5 56.3 67.4 | 72.4 |
| 2021 31.0 87.5 132.3 145.6 | 150.9 |
| 2022 71.7 194.5 232.0 | 250.2 |
| 2023 20.2 53.8 | 78.5 |
| 2024 55.4 | 134.6 |
| 2025 | 142.8 |
| Total | 942.2 |
| All outstanding liabilities before 2016, net of reinsurance | 2.4 |
| Loss and LAE reserves, net of reinsurance | **$578.3** |

| Property and Accident & Health | Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance |  |  |  |  |  |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| **Years** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10** |
|  | 27.4% | 31.9% | 18.4% | 6.4% | 2.9% | 1.9% | 0.4% | 0.9% | 0.2% | 0.1% |

95

*$ in Millions*

| Marine & Energy Accident Year | Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | As of December 31, 2025 Total IBNR plus expected development on reported claims | Cumulative number of reported claims |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 2016 | $23.8 | $20.0 | $16.0 | $14.9 | $14.6 | $15.2 | $14.5 | $14.0 | $13.7 | $13.8 | $— | 3,776 |
| 2017 |  | 26.5 | 19.7 | 17.9 | 17.3 | 16.9 | 16.0 | 16.3 | 16.4 | 16.4 | .2 | 4,141 |
| 2018 |  |  | 26.2 | 20.6 | 18.1 | 18.5 | 18.0 | 18.4 | 17.4 | 17.0 | .2 | 3,245 |
| 2019 |  |  |  | 24.2 | 22.0 | 22.1 | 21.9 | 22.3 | 21.6 | 21.8 | .4 | 2,413 |
| 2020 |  |  |  |  | 30.4 | 27.7 | 29.1 | 27.9 | 27.6 | 27.6 | .8 | 1,594 |
| 2021 |  |  |  |  |  | 87.7 | 70.5 | 68.4 | 75.6 | 79.8 | 3.8 | 1,530 |
| 2022 |  |  |  |  |  |  | 150.8 | 154.9 | 157.5 | 218.6 | 56.8 | 2,083 |
| 2023 |  |  |  |  |  |  |  | 198.6 | 189.9 | 123.2 | 36.8 | 2,341 |
| 2024 |  |  |  |  |  |  |  |  | 243.3 | 248.1 | 138.4 | 2,195 |
| 2025 |  |  |  |  |  |  |  |  |  | 235.3 | 184.9 | 1,618 |
|  |  |  |  |  |  |  |  |  | Total | **$1,001.6** |  |  |

| Marine & Energy Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 | 2025 |
| --- | ---: |
| 2016 $5.6 $10.2 $12.9 $13.3 $13.4 $14.1 $13.8 $13.8 $13.8 | $13.8 |
| 2017 5.2 11.3 13.1 14.4 14.4 14.3 14.3 14.6 | 15.9 |
| 2018 2.7 12.9 14.6 15.3 16.0 15.9 16.1 | 16.3 |
| 2019 3.4 10.9 12.9 14.7 15.7 18.4 | 19.3 |
| 2020 3.2 12.9 16.3 18.9 22.4 | 23.2 |
| 2021 6.4 24.9 38.9 52.7 | 64.4 |
| 2022 12.3 66.7 98.6 | 145.5 |
| 2023 10.6 42.7 | 61.3 |
| 2024 21.4 | 60.1 |
| 2025 | 19.4 |
| Total | 439.2 |
| All outstanding liabilities before 2016, net of reinsurance | 6.6 |
| Loss and LAE reserves, net of reinsurance | **$569.0** |

| Marine & Energy | Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance |  |  |  |  |  |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| **Years** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10** |
|  | 12.1% | 27.1% | 17.3% | 12.1% | 6.4% | 6.5% | 0.5% | 0.4% | 0.1% | 0.1% |

96

*$ in Millions*

| Specialty Accident Year | Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | As of December 31, 2025 Total IBNR plus expected development on reported claims | Cumulative number of reported claims |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 2016 | $18.5 | $14.5 | $11.1 | $11.4 | $12.0 | $12.0 | $9.1 | $8.6 | $12.5 | $12.2 | $.2 | 1,936 |
| 2017 |  | 18.3 | 13.2 | 12.3 | 11.8 | 11.9 | 10.9 | 10.6 | 11.2 | 11.1 | — | 2,201 |
| 2018 |  |  | 14.7 | 16.6 | 17.0 | 16.2 | 15.1 | 15.9 | 16.9 | 17.5 | .9 | 2,129 |
| 2019 |  |  |  | 22.1 | 19.8 | 18.9 | 25.9 | 30.1 | 20.0 | 26.8 | .7 | 2,396 |
| 2020 |  |  |  |  | 24.5 | 23.5 | 19.3 | 20.4 | 17.3 | 17.7 | 1.3 | 2,028 |
| 2021 |  |  |  |  |  | 71.8 | 63.0 | 51.8 | 44.0 | 41.7 | 6.6 | 1,735 |
| 2022 |  |  |  |  |  |  | 181.9 | 178.5 | 172.6 | 179.6 | 58.3 | 1,577 |
| 2023 |  |  |  |  |  |  |  | 216.6 | 199.4 | 153.4 | 41.3 | 1,734 |
| 2024 |  |  |  |  |  |  |  |  | 223.2 | 231.3 | 133.2 | 1,798 |
| 2025 |  |  |  |  |  |  |  |  |  | 226.8 | 169.4 | 1,831 |
|  |  |  |  |  |  |  |  |  | Total | **$918.1** |  |  |

| Specialty Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 | 2025 |
| --- | ---: |
| 2016 $3.2 $8.0 $9.2 $10.0 $10.4 $10.5 $8.7 $8.4 $11.8 | $11.8 |
| 2017 3.3 6.8 8.6 8.8 8.8 9.5 9.3 9.9 | 9.9 |
| 2018 2.9 8.5 10.2 10.6 12.0 13.2 14.4 | 14.8 |
| 2019 5.0 7.2 7.6 18.5 25.2 17.7 | 19.8 |
| 2020 5.4 11.0 13.4 18.8 18.5 | 19.2 |
| 2021 5.1 24.1 35.8 34.6 | 35.3 |
| 2022 16.1 62.5 84.9 | 113.2 |
| 2023 19.2 76.3 | 109.1 |
| 2024 28.9 | 53.8 |
| 2025 | 24.1 |
| Total | 411.0 |
| All outstanding liabilities before 2016, net of reinsurance | 1.1 |
| Loss and LAE reserves, net of reinsurance | **$508.2** |

| Specialty | Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance |  |  |  |  |  |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| **Years** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10** |
|  | 18.2% | 26.8% | 13.2% | 8.7% | 6.3% | 2.5% | 2.1% | 1.8% | (1.2)% | 1.0% |

97

*$ in Millions*

| Casualty-Active Accident Year | Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | As of December 31, 2025 Total IBNR plus expected development on reported claims | Cumulative number of reported claims |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 2016 | $8.8 | $8.3 | $8.9 | $9.0 | $9.1 | $9.2 | $9.2 | $10.1 | $11.8 | $11.9 | $.4 | 1,606 |
| 2017 |  | 11.6 | 11.7 | 10.8 | 9.3 | 9.1 | 10.5 | 10.7 | 10.9 | 10.6 | .7 | 1,693 |
| 2018 |  |  | 12.9 | 13.3 | 11.1 | 10.9 | 8.6 | 9.2 | 9.4 | 10.5 | .9 | 1,175 |
| 2019 |  |  |  | 14.8 | 13.7 | 12.3 | 10.6 | 11.4 | 13.0 | 14.4 | 1.4 | 1,062 |
| 2020 |  |  |  |  | 13.5 | 12.1 | 10.9 | 9.2 | 8.8 | 9.5 | 1.7 | 731 |
| 2021 |  |  |  |  |  | 21.4 | 22.4 | 16.6 | 16.3 | 21.7 | 4.1 | 1,050 |
| 2022 |  |  |  |  |  |  | 33.0 | 38.1 | 34.7 | 17.3 | 9.8 | 1,774 |
| 2023 |  |  |  |  |  |  |  | 61.0 | 65.9 | 57.1 | 39.4 | 2,234 |
| 2024 |  |  |  |  |  |  |  |  | 60.0 | 82.0 | 71.9 | 2,171 |
| 2025 |  |  |  |  |  |  |  |  |  | 68.2 | 63.4 | 1,723 |
|  |  |  |  |  |  |  |  |  | Total | **$303.2** |  |  |

| Casualty-Active Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 | 2025 |
| --- | ---: |
| 2016 $.2 $1.0 $2.3 $4.0 $4.6 $5.3 $6.5 $8.1 $9.7 | $10.3 |
| 2017 .8 1.7 2.8 3.4 4.2 5.7 7.5 8.3 | 9.1 |
| 2018 .3 1.4 3.5 4.3 4.3 6.2 7.1 | 8.0 |
| 2019 .3 1.4 2.3 3.0 5.7 8.3 | 10.2 |
| 2020 .5 1.0 2.0 3.3 5.3 | 6.0 |
| 2021 .5 .9 3.1 9.6 | 12.6 |
| 2022 .5 1.6 2.5 | 3.6 |
| 2023 .9 5.6 | 10.8 |
| 2024 1.9 | 4.6 |
| 2025 | 1.0 |
| Total | 76.2 |
| All outstanding liabilities before 2016, net of reinsurance | 3.6 |
| Loss and LAE reserves, net of reinsurance | **$230.6** |

| Casualty-Active | Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance |  |  |  |  |  |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| **Years** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10** |
|  | 3.8% | 7.5% | 11.4% | 12.9% | 10.0% | 11.2% | 7.2% | 5.1% | 4.2% | 3.4% |

98

*$ in Millions*

| Casualty-Runoff Accident Year | Incurred Loss and LAE, Net of Reinsurance For the Years Ended December 31, 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | As of December 31, 2025 Total IBNR plus expected development on reported claims | Cumulative number of reported claims |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 2016 | $32.6 | $32.3 | $40.5 | $38.6 | $38.9 | $38.6 | $37.7 | $37.5 | $37.5 | $38.1 | $1.9 | 2,156 |
| 2017 |  | 30.7 | 34.0 | 31.5 | 32.1 | 31.6 | 29.9 | 28.3 | 28.5 | 27.9 | 2.0 | 1,606 |
| 2018 |  |  | 33.6 | 28.2 | 27.3 | 26.6 | 26.2 | 28.0 | 27.8 | 28.2 | 2.9 | 1,284 |
| 2019 |  |  |  | 26.5 | 23.3 | 23.4 | 24.9 | 23.6 | 23.7 | 22.5 | 4.2 | 976 |
| 2020 |  |  |  |  | 15.9 | 12.3 | 13.9 | 10.9 | 9.5 | 9.2 | 2.3 | 573 |
| 2021 |  |  |  |  |  | 10.5 | 7.0 | 5.5 | 4.5 | 3.9 | 1.5 | 284 |
| 2022 |  |  |  |  |  |  | .8 | 2.6 | 2.6 | 2.3 | 1.3 | 80 |
| 2023 |  |  |  |  |  |  |  | 2.7 | 3.6 | 3.1 | 1.8 | 40 |
| 2024 |  |  |  |  |  |  |  |  | 1.2 | 1.1 | .5 | 20 |
| 2025 |  |  |  |  |  |  |  |  |  | .7 | — | 41 |
|  |  |  |  |  |  |  |  |  | Total | **$137.0** |  |  |

| Casualty-Runoff Millions Cumulative Paid Loss and LAE, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 2017 2018 2019 2020 2021 2022 2023 2024 | 2025 |
| --- | ---: |
| 2016 $3.9 $10.2 $17.7 $22.7 $25.4 $27.8 $28.8 $31.0 $32.5 | $34.1 |
| 2017 3.2 9.4 14.7 18.5 21.4 22.5 22.8 23.5 | 24.8 |
| 2018 3.4 7.4 12.6 14.9 16.3 18.2 21.3 | 22.7 |
| 2019 3.3 5.8 7.8 12.1 15.1 15.9 | 17.3 |
| 2020 .8 1.3 3.1 6.0 6.3 | 6.5 |
| 2021 .5 1.7 1.9 2.3 | 2.4 |
| 2022 .3 .6 .7 | .9 |
| 2023 .9 1.0 | 1.1 |
| 2024 .5 | .5 |
| 2025 | .6 |
| Total | 110.9 |
| All outstanding liabilities before 2016, net of reinsurance | 31.0 |
| Loss and LAE reserves, net of reinsurance | **$57.1** |

| Casualty-Runoff | Average Annual Percentage Payout of Incurred Loss and LAE by Age, Net of Reinsurance |  |  |  |  |  |  |  |  |  |
| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| **Years** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10** |
|  | 8.8% | 13.9% | 15.3% | 14.8% | 8.5% | 6.7% | 5.9% | 4.2% | 3.2% | 2.2% |

99

### 3\. Goodwill and Other Intangible Assets

As of December 31, 2025, goodwill and other intangible assets recognized in connection with business and asset acquisitions totaled $1,020 million, of which $642 million was attributable to White Mountains’s common shareholders.

Under the acquisition method, White Mountains recognizes and measures the assets acquired, including other intangible assets, at their acquisition date fair values. Goodwill represents the excess of the amount paid to acquire a business over the fair value of identifiable net assets at the acquisition date.

Goodwill and other intangible assets with indefinite lives are not amortized but rather are evaluated for impairment on an annual basis, or whenever indications of potential impairment exist. In the absence of any indications of potential impairment, the evaluation of goodwill and indefinite-lived intangible assets is performed no later than the interim period in which the anniversary of the acquisition date falls. White Mountains initially evaluates goodwill and indefinite-lived intangible assets using a qualitative approach (step zero) to determine whether it is more likely than not that the implied fair value is greater than the carrying value. If the results of the qualitative evaluation indicate that it is more likely than not that the carrying value of goodwill or the indefinite-lived intangible assets exceeds the implied fair value, White Mountains performs a quantitative analysis to compare the fair value with the carrying value. If the carrying value exceeds the estimated fair value, then an impairment charge is recognized through current period pre-tax income (loss).

Other intangible assets with finite lives are initially measured at their acquisition date fair values and subsequently amortized over their economic lives. Finite-lived intangible assets are presented net of accumulated amortization on the balance sheet. Finite-lived intangible assets are reviewed for impairment when events occur or there are changes in circumstances indicating that their carrying value may exceed fair value. An impairment exists when the carrying value of a finite-lived intangible asset exceeds the fair value.

During the year ended December 31, 2025, White Mountains performed its periodic reviews for potential impairment and recognized an impairment of goodwill of $9 million and other intangible assets of $1 million related to an Other Operating Business within Other Operations. Impairment charges are presented within general and administrative expenses on the statement of operations.

As of December 31, 2025, White Mountains had total goodwill and other intangible assets of $1,020 million, $578 million of which relates to Distinguished and $293 million of which relates to Ark. See **Note 4 — “Goodwill and Other Intangible Assets”** on page F-34.

See **Item 1A. Risk Factors, “*****If we are required to write down goodwill and other intangible assets, it could materially adversely affect our results of operations and financial condition.”*** on page 29.

### FORWARD-LOOKING STATEMENTS

This report may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included or referenced in this report which address activities, events or developments which White Mountains expects or anticipates will or may occur in the future are forward-looking statements. The words “could”, “will”, “believe”, “intend”, “expect”, “anticipate”, “project”, “estimate”, “predict” and similar expressions are also intended to identify forward-looking statements. These forward-looking statements include, among others, statements with respect to White Mountains’s:

- change in book value per share or return on equity;
- business strategy;
- financial and operating targets or plans;
- incurred loss and LAE and the adequacy of its loss and LAE reserves and related reinsurance;
- projections of revenues, income (or loss), earnings (or loss) per share, EBITDA, adjusted EBITDA, dividends, market share or other financial forecasts of White Mountains or its businesses;
- expansion and growth of its business and operations; and
- future capital expenditures.

These statements are based on certain assumptions and analyses made by White Mountains in light of its experience and perception of historical trends, current conditions and expected future developments, as well as other factors believed to be appropriate in the circumstances. However, whether actual results and developments will conform to its expectations and predictions is subject to risks and uncertainties that could cause actual results to differ materially from expectations, including:

- the risks associated with Item 1A of this Report on Form 10-K;
- claims arising from catastrophic events, such as hurricanes, windstorms, earthquakes, floods, wildfires, tornadoes, tsunamis, severe weather, public health crises, terrorist attacks, war and war-like actions, explosions, infrastructure failures or cyber attacks;
- recorded loss reserves subsequently proving to have been inadequate;
- the market value of White Mountains’s investment in MediaAlpha;
- business opportunities (or lack thereof) that may be presented to it and pursued;
- actions taken by rating agencies, such as financial strength or credit ratings downgrades or placing ratings on negative watch;
- the continued availability of capital and financing;
- the continued availability of fronting and reinsurance capacity;
- deterioration of general economic, market or business conditions, including due to outbreaks of contagious disease and corresponding mitigation efforts;
- competitive forces, including the conduct of other insurers;
- changes in domestic or foreign laws or regulations, or their interpretation, applicable to White Mountains, its competitors or its customers; and
- other factors, most of which are beyond White Mountains’s control.

Consequently, all of the forward-looking statements made in this report are qualified by these cautionary statements, and there can be no assurance that the actual results or developments anticipated by White Mountains will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, White Mountains or its business or operations. White Mountains assumes no obligation to publicly update any such forward-looking statements, whether as a result of new information, future events or otherwise.

## Market risk

As filed, 8,009 characters.

White Mountains’s consolidated balance sheet includes a substantial amount of assets and liabilities whose fair values are subject to market risk. The term market risk refers to the risk of loss arising from adverse changes in interest rates, credit spreads, equity markets prices and other relevant market rates and prices. Due to the size of White Mountains’s investment portfolio, market risk could have a significant effect on White Mountains’s consolidated financial condition, results of operations and cash flows.

### Interest Rate and Credit Spread Risk

White Mountains invests in interest rate sensitive securities. White Mountains generally manages the interest rate risk associated with its portfolio of fixed maturity investments by monitoring the average duration of the portfolio. As of December 31, 2025, White Mountains’s fixed maturity investments are comprised primarily of debt securities issued by corporations, U.S. government and agency obligations, foreign government and agency obligations, mortgage and asset-backed securities and collateralized loan obligations.

Increases and decreases in prevailing interest rates generally translate into decreases and increases in fair values of fixed maturity investments, respectively. Additionally, fair values of interest rate sensitive instruments may be affected by the creditworthiness of the issuer, prepayment options, relative values of alternative investments, the liquidity of the instrument and various other market factors.

The following table presents the estimated effects of hypothetical increases and decreases in market interest rates on White Mountains’s fixed maturity investments:

*$ in Millions*

|  | Fair Value at December 31, 2025 | Assumed Change in Relevant Interest Rate | Estimated Fair Value After Change in Interest Rate | Pre-Tax Increase (Decrease) in Fair Value |
| --- | ---: | --- | ---: | ---: |
| Fixed maturity investments | **$2,770.5** | 100 bps decrease | $2,839.6 | $69.1 |
|  |  | 50 bps decrease | 2,805.3 | 34.8 |
|  |  | 50 bps increase | 2,735.5 | (35.0) |
|  |  | 100 bps increase | 2,700.5 | (70.0) |

The magnitude of the fair value decrease in rising interest rate scenarios may be more significant than the fair value increase in comparable falling interest rate scenarios. This can occur because (i) the analysis floors interest rates at a de minimis level in falling interest rate scenarios, muting price increases, (ii) portions of the fixed maturity investment portfolio may be callable, muting price increases in falling interest rate scenarios and/or (iii) portions of the fixed maturity investment portfolio may experience cash flow extension in higher interest rate environments, which generally results in lower prices.

White Mountains’s overall strategy for fixed maturity investments is to purchase securities that are attractively priced in relation to their investment risks. Widening and tightening of credit spreads translate into decreases and increases in fair values of fixed maturity investments, respectively.

The following table presents the estimated pre-tax effects of hypothetical widening and tightening of credit spreads on White Mountains’s fixed maturity investments by asset class:

| Millions | December 31, 2025 Fair Value | Tighten 50 | Tighten 25 | Widen 25 | Widen 50 |
| --- | ---: | ---: | ---: | ---: | ---: |
| U.S. government and agency obligations | **$460.3** | $— | $— | $— | $— |
| Foreign government and agency obligations | **32.5** | — | — | — | — |
|  |  | **Tighten 100** | **Tighten 50** | **Widen 50** | **Widen 100** |
| Agency mortgage-backed securities | **354.0** | 5.1 | 5.1 | (10.3) | (20.1) |
| Other asset-backed securities | **39.0** | .6 | .5 | (.6) | (1.2) |
|  |  | **Tighten 200** | **Tighten 100** | **Widen 100** | **Widen 200** |
| Debt securities issued by corporations | **1,537.7** | 15.8 | 15.4 | (38.9) | (77.8) |
|  |  | **Tighten 300** | **Tighten 200** | **Widen 200** | **Widen 300** |
| Collateralized loan obligations | **347.0** | 28.6 | 27.8 | (38.7) | (58.1) |

The magnitude of the fair value decrease in wider credit spread scenarios may be more significant than the fair value increase in comparable tighter credit spread scenarios. This can occur because the analysis limits the credit spread tightening in order to establish a floor for yields of non-government bonds above yields of government bonds, thereby muting price increases.

### Common Equity Securities, Investment in MediaAlpha and Other Long-Term Investments Price Risk

The carrying values of White Mountains’s common equity securities, investment in MediaAlpha and other long-term investments are based on quoted market prices or management’s estimates of fair value as of the balance sheet date. Market prices of common equity securities, in general, are subject to fluctuations, which could cause the amount realized upon sale or exercise of these instruments to differ significantly from the current reported value. The fluctuations may result from perceived changes in the underlying economic characteristics of the investment, the relative price of alternative investments, supply and demand imbalances for a particular security or various other market factors. Assuming a hypothetical 10% and 30% increase or decrease in the value of White Mountains’s common equity securities, investment in MediaAlpha and other long-term investments as of December 31, 2025, the carrying value of White Mountains’s common equity securities, investment in MediaAlpha and other long-term investments would increase or decrease by $367 million and $1,102 million, respectively, on a pre-tax basis. See “**CRITICAL ACCOUNTING ESTIMATES — Fair Value Measurements”** on page 88 for further discussion related to the valuation of Kudu’s Participation Contracts and White Mountains’s investment in PassportCard/DavidShield.

### BAM Surplus Notes

The carrying value of the BAM Surplus Notes is based on management’s estimate of fair value as of the balance sheet date. Assuming a hypothetical 10% and 30% increase or decrease in the value of the BAM Surplus Notes as of December 31, 2025, the carrying value of the BAM Surplus Notes would increase or decrease by $34 million and $102 million, respectively, on a pre-tax basis. See “**CRITICAL ACCOUNTING ESTIMATES — Fair Value Measurements”** on page 88 for further discussion related to the valuation of the BAM Surplus Notes.

### Long-Term Obligations

White Mountains carries its debt obligations at face value less unamortized debt issuance costs and original issue discount. White Mountains is required to disclose the fair value of certain financial instruments not carried at fair value, including the debt obligations. See **Note 18 — “Fair Value of Financial Instruments”** on page F-78 for the fair value and carrying value of White Mountains’s debt obligations as of December 31, 2025 and 2024.

### Foreign Currency Exposure

As of December 31, 2025, White Mountains had net assets of $376 million denominated in foreign currencies primarily related to Ark/WM Outrigger’s non-U.S. contracts, Kudu’s non-U.S. Participation Contracts and a private debt instrument, as well as certain other foreign consolidated and unconsolidated entities. See “***Summary of Investment Results -*** **Foreign Currency Exposure”** on page 78 for fair value of White Mountains’s foreign denominated net assets (liabilities) by segment as of December 31, 2025.

The following table illustrates the pre-tax effect of a hypothetical 20% increase (decrease) in the U.S. dollar exchange rate on the carrying value of net assets denominated in foreign currencies as of December 31, 2025:

*$ in Millions*

| Carrying Value of Foreign Denominated Net Assets | Hypothetical Change | Hypothetical Pre-Tax Increase (Decrease) in Carrying Value | Hypothetical Percentage Increase (Decrease) in Stockholders’ Equity |
| ---: | --- | ---: | ---: |
| **$376.4** | 20% increase | $(75.3) | (1.2)% |
|  | 20% decrease | $75.3 | 1.2% |

## Controls and procedures

As filed, 1,244 characters.

The Principal Executive Officer (“PEO”) and the Principal Financial Officer (“PFO”) of White Mountains have evaluated the effectiveness of its disclosure controls and procedures (as defined in Rule 13a-15(e) of the Exchange Act) as of December 31, 2025. Based on that evaluation, the PEO and PFO have concluded that White Mountains’s disclosure controls and procedures are adequate and effective.

The PEO and the PFO of White Mountains have evaluated the effectiveness of its internal control over financial reporting as of December 31, 2025. Based on that evaluation, the PEO and PFO have concluded that White Mountains’s internal control over financial reporting is effective. Management’s annual report on internal control over financial reporting is included on page F-80 of this report. The attestation report on the effectiveness of White Mountains’s internal control over financial reporting by PricewaterhouseCoopers LLP is included on page F-81 of this report.

There were no changes to White Mountains’s internal controls over financial reporting that occurred during the fourth quarter of 2025 that have materially affected, or are reasonably likely to materially affect, White Mountains’s internal control over financial reporting.

Filed Feb 27, 2026.
Source: SEC EDGAR, the filing index for accession 0001628280-26-012603. Last ingested by Listed: Oct 30, 2026, 21:03 ET. No prices; not investment advice.