# Castle Biosciences Inc: overview

CSTL · Nasdaq · CIK 1447362 · [Healthcare](/sectors/healthcare.md) · fiscal year ends Dec 31

Pages: [Overview](/companies/cstl.md) · [Financials](/companies/cstl/financials.md) · [Filings](/companies/cstl/filings.md) · [Insiders](/companies/cstl/insiders.md)

Latest reported revenue: [$103.5m](/filings/0001628280-26-051052.md) for Q2 FY2026, three months to 2026-06-30, from the 10-Q filed Jul 30, 2026 (XBRL us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax, accession 0001628280-26-051052).

## Last eight quarters

| Line item | Unit | Q3 FY2024 (2024-09-30) | Q4 FY2024 (2024-12-31) | Q1 FY2025 (2025-03-31) | Q2 FY2025 (2025-06-30) | Q3 FY2025 (2025-09-30) | Q4 FY2025 (2025-12-31) | Q1 FY2026 (2026-03-31) | Q2 FY2026 (2026-06-30) |
| --- | --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| Revenue | $m | [85.8](/filings/0001628280-25-048254.md) | [86.3 d](/filings/0001628280-26-012272.md) | [88.0](/filings/0001628280-26-031263.md) | [86.2](/filings/0001628280-26-051052.md) | [83.0](/filings/0001628280-25-048254.md) | [87.0 d](/filings/0001628280-26-012272.md) | [83.7](/filings/0001628280-26-031263.md) | [104](/filings/0001628280-26-051052.md) |
| Gross margin | % | not reported | not reported | not reported | not reported | not reported | not reported | not reported | not reported |
| Operating margin | % | [5.9%](/filings/0001628280-25-048254.md) | [4.7% d](/filings/0001628280-26-012272.md) | [(31.7%)](/filings/0001628280-26-031263.md) | [(4.9%)](/filings/0001628280-26-051052.md) | [(8.2%)](/filings/0001628280-25-048254.md) | [(4.4%) d](/filings/0001628280-26-012272.md) | [(22.0%)](/filings/0001628280-26-031263.md) | [(3.0%)](/filings/0001628280-26-051052.md) |
| Net margin | % | [2.6%](/filings/0001628280-25-048254.md) | [11.1% d](/filings/0001628280-26-012272.md) | [(29.4%)](/filings/0001628280-26-051052.md) | [5.2%](/filings/0001628280-26-051052.md) | [(0.6%)](/filings/0001628280-25-048254.md) | [(2.7%) d](/filings/0001628280-26-012272.md) | [(17.4%)](/filings/0001628280-26-051052.md) | [(2.0%)](/filings/0001628280-26-051052.md) |
| Diluted EPS | $ per share | [0.08](/filings/0001628280-25-048254.md) | not reported | [(0.90)](/filings/0001628280-26-031263.md) | [0.15](/filings/0001628280-26-051052.md) | [(0.02)](/filings/0001628280-25-048254.md) | not reported | [(0.49)](/filings/0001628280-26-031263.md) | [(0.07)](/filings/0001628280-26-051052.md) |
| Free cash flow | $m | [17.0 d](/filings/0001628280-25-048254.md) | [16.8 d](/filings/0001628280-26-012272.md) | [(10.8)](/filings/0001628280-26-031263.md) | [11.6 d](/filings/0001628280-26-051052.md) | [7.8 d](/filings/0001628280-25-048254.md) | [19.7 d](/filings/0001628280-26-012272.md) | [(34.6)](/filings/0001628280-26-031263.md) | [6.6 d](/filings/0001628280-26-051052.md) |

- Revenue. XBRL Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax. Derived values: 12-month figure less the 9-month figure.
- Gross margin (gross profit / revenue). XBRL Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax. Derived values: 12-month figure less the 9-month figure.
- Operating margin (operating income / revenue). XBRL Operating income: us-gaap:OperatingIncomeLoss; Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax. Derived values: 12-month figure less the 9-month figure.
- Net margin (net income / revenue). XBRL Net income: us-gaap:NetIncomeLoss; Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax. Derived values: 12-month figure less the 9-month figure.
- Diluted EPS. XBRL Diluted EPS: us-gaap:EarningsPerShareDiluted.
- Free cash flow (operating cash flow − capital expenditure). XBRL Operating cash flow: us-gaap:NetCashProvidedByUsedInOperatingActivities; Capital expenditure: us-gaap:PaymentsToAcquirePropertyPlantAndEquipment. Derived values: 9-month figure less the 6-month figure; 12-month figure less the 9-month figure; 6-month figure less the 3-month figure.

## Last five fiscal years

| Line item | Unit | FY2021 (2021-12-31) | FY2022 (2022-12-31) | FY2023 (2023-12-31) | FY2024 (2024-12-31) | FY2025 (2025-12-31) |
| --- | --- | ---: | ---: | ---: | ---: | ---: |
| Revenue | $m | [94.1](/filings/0001447362-23-000038.md) | [137](/filings/0001447362-25-000031.md) | [220](/filings/0001628280-26-012272.md) | [332](/filings/0001628280-26-012272.md) | [344](/filings/0001628280-26-012272.md) |
| Gross margin | % | not reported | not reported | not reported | not reported | not reported |
| Operating margin | % | [(42.6%)](/filings/0001447362-23-000038.md) | [(53.2%)](/filings/0001447362-25-000031.md) | [(30.9%)](/filings/0001628280-26-012272.md) | [2.6%](/filings/0001628280-26-012272.md) | [(12.4%)](/filings/0001628280-26-012272.md) |
| Net margin | % | [(33.3%)](/filings/0001447362-23-000038.md) | [(49.0%)](/filings/0001447362-25-000031.md) | [(26.1%)](/filings/0001628280-26-012272.md) | [5.5%](/filings/0001628280-26-012272.md) | [(7.0%)](/filings/0001628280-26-012272.md) |
| Diluted EPS | $ per share | [(1.24)](/filings/0001447362-23-000038.md) | [(2.58)](/filings/0001447362-25-000031.md) | [(2.14)](/filings/0001628280-26-012272.md) | [0.62](/filings/0001628280-26-012272.md) | [(0.83)](/filings/0001628280-26-012272.md) |
| Free cash flow | $m | [(22.5)](/filings/0001447362-23-000038.md) | [(47.3)](/filings/0001447362-25-000031.md) | [(19.2)](/filings/0001628280-26-012272.md) | [36.5](/filings/0001628280-26-012272.md) | [28.3](/filings/0001628280-26-012272.md) |

- Revenue. XBRL Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax.
- Gross margin (gross profit / revenue). XBRL Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax.
- Operating margin (operating income / revenue). XBRL Operating income: us-gaap:OperatingIncomeLoss; Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax.
- Net margin (net income / revenue). XBRL Net income: us-gaap:NetIncomeLoss; Revenue: us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax.
- Diluted EPS. XBRL Diluted EPS: us-gaap:EarningsPerShareDiluted.
- Free cash flow (operating cash flow − capital expenditure). XBRL Operating cash flow: us-gaap:NetCashProvidedByUsedInOperatingActivities; Capital expenditure: us-gaap:PaymentsToAcquirePropertyPlantAndEquipment.

Each value links to the filing it came from. d marks a derived value. A ratio is not reported when any input is missing.

## Insider purchases and sales

The last 20 open-market transactions on Form 4 (codes P and S). Reported price is as stated on the form, not a market price. [All insider transactions](/companies/cstl/insiders.md)

| Date | Insider | Role | Transaction | Shares | Reported price | Value | Filing |
| --- | --- | --- | --- | ---: | ---: | ---: | --- |
| 2026-10-26 | [Juvenal Tobin W](/insiders/1856542.md) | Chief Commercial Officer, Officer | Sale (S) | 3,288 | $33.08 | $108.8k | [Form 4](/filings/0001628280-26-067887.md) |

## Funds that report holding it

From each manager’s latest Form 13F, largest reported value first. Reported value is as filed: filing data, not a price. [All funds](/funds.md)

| Fund | Quarter ended | Reported value | Shares | Put or call | Change on the quarter before |
| --- | --- | ---: | ---: | --- | --- |
| [BlackRock, Inc.](/funds/2012383.md) | 2026-06-30 | $78.5m | 3,291,963 |  | Added +309,017 |
| [RTW INVESTMENTS, LP](/funds/1493215.md) | 2026-06-30 | $66.3m | 2,778,335 |  | Added +20,000 |
| [PRINCIPAL FINANCIAL GROUP INC](/funds/1126328.md) | 2026-06-30 | $41.2m | 1,726,648 |  | Reduced −43,229 |
| [VANGUARD CAPITAL MANAGEMENT LLC](/funds/2100119.md) | 2026-06-30 | $29.3m | 1,226,497 |  | Added +48,975 |
| [VANGUARD PORTFOLIO MANAGEMENT LLC](/funds/2100121.md) | 2026-06-30 | $20.1m | 840,785 |  | Reduced −20,986 |
| [Allianz Asset Management GmbH](/funds/1535323.md) | 2026-06-30 | $19.9m | 811,324 |  | Unchanged |
| [SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC](/funds/1638555.md) | 2026-06-30 | $19.7m | 824,872 |  | Reduced −115,813 |
| [STATE STREET CORP](/funds/93751.md) | 2026-06-30 | $19.6m | 822,079 |  | Added +53,000 |
| [GEODE CAPITAL MANAGEMENT, LLC](/funds/1214717.md) | 2026-06-30 | $19.0m | 795,912 |  | Added +67,812 |
| [MACKENZIE FINANCIAL CORP](/funds/919859.md) | 2026-06-30 | $18.9m | 793,507 |  | Added +719,396 |

## Recent filings

[All 884 filings](/companies/cstl/filings.md)

| Filed | Accepted | Form | What it is | Accession |
| --- | --- | --- | --- | --- |
| 2026-07-30 | 16:09 ET | [10-Q](/filings/0001628280-26-051052.md) | Quarterly report, period 2026-06-30 | 0001628280-26-051052 |
| 2026-07-30 | 16:06 ET | [8-K](/filings/0001628280-26-051045.md) | 2.02 Results of operations; 7.01 Regulation FD disclosure; 9.01 Financial statements and exhibits | 0001628280-26-051045 |
| 2026-05-29 | 16:14 ET | [8-K](/filings/0001628280-26-039189.md) | 5.07 Shareholder vote results | 0001628280-26-039189 |
| 2026-05-06 | 16:09 ET | [10-Q](/filings/0001628280-26-031263.md) | Quarterly report, period 2026-03-31 | 0001628280-26-031263 |
| 2026-05-06 | 16:07 ET | [8-K](/filings/0001628280-26-031255.md) | 2.02 Results of operations; 7.01 Regulation FD disclosure; 9.01 Financial statements and exhibits | 0001628280-26-031255 |
| 2026-04-08 | 10:13 ET | [DEF 14A](/filings/0001628280-26-024166.md) | Proxy statement, period 2026-05-28 | 0001628280-26-024166 |
| 2026-02-26 | 16:09 ET | [10-K](/filings/0001628280-26-012272.md) | Annual report, period 2025-12-31 | 0001628280-26-012272 |
| 2026-02-26 | 16:07 ET | [8-K](/filings/0001628280-26-012263.md) | 2.02 Results of operations; 7.01 Regulation FD disclosure; 9.01 Financial statements and exhibits | 0001628280-26-012263 |
| 2026-01-13 | 09:43 ET | [8-K](/filings/0001628280-26-001909.md) | 2.02 Results of operations; 7.01 Regulation FD disclosure; 9.01 Financial statements and exhibits | 0001628280-26-001909 |
| 2025-11-03 | 16:16 ET | [10-Q](/filings/0001628280-25-048254.md) | Quarterly report, period 2025-09-30 | 0001628280-25-048254 |

## Latest annual report

[Form 10-K for the fiscal year ended Dec 31, 2025](/filings/0001628280-26-012272.md), filed Feb 26, 2026.

## Forecast league

Q3 FY2026, the quarter ended 2026-09-30, is open for forecasts until the first results filing for it is accepted by EDGAR. Results are due by \[object Promise\]. [Forecast this quarter](/leagues/2026q3/targets/3764ea46-2451-4774-b507-9a350232df3a)

## About the filer

- CIK: 1447362
- Tickers: CSTL
- Exchange: Nasdaq
- SIC code: 8071 Services-Medical Laboratories
- State of incorporation: DE
- Filer category: Accelerated filer

Source: SEC EDGAR, XBRL company facts, the filing index and Forms 4. Last ingested by Listed: Oct 30, 2026, 16:13 ET. No prices; not investment advice.