Castle Biosciences Inc
CSTL- Exchange
- Nasdaq
- Industry
- Services-Medical Laboratories
- SEC CIK
- 0001447362
In the last 90 days, Castle Biosciences Inc insiders filed 0 open-market purchases and 20 sales; 176 institutions reported holding it in 13F filings for Q2 2026, worth $653.8M in total; no superinvestor holds it.
Key figures
- Market capClose on Nov 12, 2026
- $1.06B
- Insider buysOpen market, last 90 days
- 0
- Insider sellsLast 90 days, $6.72M in total
- 20
- 13F holdersQ2 2026, −7 vs. previous quarter
- 176
- 13F valueReported value at the end of Q2 2026
- $653.8M
- Superinvestors holdingAt the end of Q2 2026
- 0
Price chart
Financials
See financial statementsFrom SEC filings, in USD.
- Revenue, FY2025
- $344.2M
- +3.7% year over year
- Net income, FY2025
- -$24.2M
- −232.4% year over year
- Free cash flow, FY2025
- $28.3M
- −22.5% year over year
- Revenue, Q3 FY2026
- $102.9M
- +23.9% year over year
Revenue flow, FY2025
Green is profit; orange is costs, expenses and taxes. Percentages are shares of revenue.
Net loss for FY2025: $24.2M (7.0% of revenue).
Short interest
See short dataFrom FINRA, settlement date Oct 30, 2026.
- Short interest
- 2.11M
- Shares sold short
- Change
- +92.5K
- +4.6% vs. previous
- Days to cover
- 6.06
- At average daily volume
Superinvestors holding CSTL, Q2 2026
Go to the superinvestors tabNo superinvestor reported holding CSTL at the end of Q2 2026.
Latest insider trades
See all insider tradesOpen-market purchases and sales by Castle Biosciences Inc insiders from Form 4, newest first.
| Filed (ET) | Trade date | Filing delay | Insider | Transaction | Shares | Avg price | Value | Holding change | Flags |
|---|---|---|---|---|---|---|---|---|---|
| Nov 12, 2026 (view filing)4:13 PM ET | Nov 9-11 | 3 days | Juvenal Tobin WChief Commercial Officer | SSale | −6.12K | $33.77 | −$206.5K | −15.7%32.7K after | 2 lots10b5-1 |
| Nov 4, 2026 (view filing)4:07 PM ET | Nov 2 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −8.58K | $36.10 | −$309.8K | −68.7%3.90K after | 2 lots10b5-1 |
| Nov 4, 2026 (view filing)4:07 PM ET | Nov 2 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −5.92K | $36.10 | −$213.6K | −80.9%1.40K after | 4 lots10b5-1 |
| Oct 30, 2026 (view filing)4:06 PM ET | Oct 28 | 2 days | Juvenal Tobin WChief Commercial Officer | SSale | −6.58K | $36.42 | −$239.6K | −14.5%38.9K after | 2 lots10b5-1 |
| Oct 28, 2026 (view filing)4:08 PM ET | Oct 26 | 2 days | Juvenal Tobin WChief Commercial Officer | SSale | −3.29K | $33.08 | −$108.8K | −6.7%45.4K after | 10b5-1 |
| Oct 21, 2026 (view filing)4:18 PM ET | Oct 19 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −8.58K | $31.91 | −$273.8K | −40.7%12.5K after | 10b5-1 |
| Oct 21, 2026 (view filing)4:18 PM ET | Oct 19 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −5.92K | $31.91 | −$188.8K | −59.0%4.11K after | 2 lots10b5-1 |
| Oct 14, 2026 (view filing)4:06 PM ET | Oct 12 | 2 days | Juvenal Tobin WChief Commercial Officer | SSale | −3.29K | $33.64 | −$110.6K | −6.3%48.7K after | 10b5-1 |
| Oct 7, 2026 (view filing)4:10 PM ET | Oct 5 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −8.58K | $35.57 | −$305.2K | −28.9%21.1K after | 10b5-1 |
| Oct 7, 2026 (view filing)4:10 PM ET | Oct 5 | 2 days | Maetzold Derek JPres. & Chief Exec. Officer | SSale | −5.92K | $35.57 | −$210.4K | −46.4%6.83K after | 2 lots10b5-1 |
Top 10 13F holders, Q2 2026
See all 176 holdersThe largest institutional positions in Castle Biosciences Inc at the end of Q2 2026; share changes are against Q1 2026.
| Institution | Shares | Value | % of portfolio | Change in shares | Action |
|---|---|---|---|---|---|
| BlackRock, Inc. | 3,291,963 | $78.5M | 0.00% | +309,017+10.4% | Added |
| RTW Investments, LP | 2,778,335 | $66.3M | 0.57% | +20,000+0.7% | Added |
| Principal Financial Group Inc | 1,726,648 | $41.2M | 0.02% | −43,229−2.4% | Reduced |
| Vanguard Capital Management LLC | 1,226,497 | $29.3M | 0.00% | +48,975+4.2% | Added |
| Acadian Asset Management LLC | 918,668 | $21.9M | 0.03% | +434,227+89.6% | Added |
| Allianz Asset Management GmbH | 879,258 | $21.0M | 0.02% | +67,934+8.4% | Added |
| Vanguard Portfolio Management LLC | 840,785 | $20.1M | 0.00% | −20,986−2.4% | Reduced |
| Summit Partners Public Asset Management, LLC | 824,872 | $19.7M | 0.51% | −115,813−12.3% | Reduced |
| State Street Corp | 822,079 | $19.6M | 0.00% | +53,000+6.9% | Added |
| Geode Capital Management, LLC | 795,912 | $19.0M | 0.00% | +67,812+9.3% | Added |
Holders of 5% or more of CSTL
See all 2 holders and filingsHolders whose latest Schedule 13D or 13G filing reports 5% or more of Castle Biosciences Inc.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| RTW Investments, LP | 13G/A | 9.30%2.76M shares | +2.10 ppfrom 7.20% | Feb 17, 20262 filings | May 15, 2026 | SEC |
| BlackRock, Inc. | 13G/A | 8.20%2.34M shares | – | Apr 23, 20251 filing | Apr 23, 2025 | SEC |
Politician trades
All politician trades in CSTL2 members of Congress reported 3 trades in Castle Biosciences Inc since 2020. Newest filings:
| Filed | Politician | Type | Amount |
|---|---|---|---|
| Apr 17, 2022 |  Josh Gottheimer House · NJ | Sell (partial) | $1K-$15K |
| Jan 11, 2021 |  Gilbert Ray Cisneros, Jr. House · CA | Buy | $1K-$15K |
| Jan 7, 2021 | Josh Gottheimer House · NJ | Buy | $1K-$15K |
House · NJ · Apr 17, 2022
Sell (partial)$1K-$15K
House · CA · Jan 11, 2021
Buy$1K-$15K
House · NJ · Jan 7, 2021
Buy$1K-$15K