CASTLE BIOSCIENCES INC CSTL
COM · Common Stock · CUSIP 14843C105 · ISIN US14843C1053
- SectorHealth care
- IndustryServices-Medical Laboratories
- HeadquartersFriendswood, TX
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($3.8m this quarter). Holder counts are more reliable. Shares outstanding: 30.5m as of 2026-07-23, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $23.87. Options: 1 managers hold calls ($54.9k notional), 0 hold puts (—).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 157 |
| Q4 2022 | 154 |
| Q1 2023 | 149 |
| Q2 2023 | 131 |
| Q3 2023 | 136 |
| Q4 2023 | 154 |
| Q1 2024 | 152 |
| Q2 2024 | 160 |
| Q3 2024 | 186 |
| Q4 2024 | 197 |
| Q1 2025 | 181 |
| Q2 2025 | 153 |
| Q3 2025 | 173 |
| Q4 2025 | 195 |
| Q1 2026 | 187 |
| Q2 2026 | 177 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q3 2024 | 114 | 63 |
| Q4 2024 | 100 | 92 |
| Q1 2025 | 102 | 98 |
| Q2 2025 | 84 | 87 |
| Q3 2025 | 98 | 67 |
| Q4 2025 | 102 | 85 |
| Q1 2026 | 96 | 97 |
| Q2 2026 | 99 | 86 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $983.7k | $215.8k | 0.22 |
| Q4 2025 | $2.8m | $0 | 0.00 |
| Q1 2026 | $1.9m | $437.0k | 0.23 |
| Q2 2026 | $54.9k | $0 | 0.00 |
Biggest buyers
| MACKENZIE FINANCIAL CORP | Added | +719.4k |
| Jefferies Financial Group Inc. | New | +647.4k |
| ACADIAN ASSET MANAGEMENT LLC | Added | +434.2k |
| Point72 Asset Management, L.P. | New | +357.3k |
| KENNEDY CAPITAL MANAGEMENT LLC | New | +348.4k |
| BlackRock, Inc. | Added | +309.0k |
| FIRST TRUST ADVISORS LP | New | +145.1k |
| CITADEL ADVISORS LLC | Added | +144.4k |
| Allspring Global Investments Holdings, LLC | Added | +131.8k |
| AQR CAPITAL MANAGEMENT LLC | Added | +101.7k |
Biggest sellers
| Portolan Capital Management, LLC | Reduced | -1.0m |
| EVENTIDE ASSET MANAGEMENT, LLC | Sold out | -386.4k |
| PALISADE CAPITAL MANAGEMENT, LP | Reduced | -304.0k |
| SCHRODER INVESTMENT MANAGEMENT GROUP | Sold out | -298.9k |
| Nuveen, LLC | Reduced | -290.4k |
| DIMENSIONAL FUND ADVISORS LP | Reduced | -248.7k |
| SG Americas Securities, LLC | Sold out | -244.9k |
| TUDOR INVESTMENT CORP ET AL | Reduced | -208.5k |
| WASATCH ADVISORS LP | Reduced | -175.7k |
| RENAISSANCE TECHNOLOGIES LLC | Reduced | -161.6k |
Biggest calls
| SIMPLEX TRADING, LLC | Reduced | $54.9k2.3k shares |
Biggest puts
| None |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| RTW INVESTMENTS, LP 13G · institution +2.1 pts · filed 2026-05-15 | 9.3% |
| BlackRock, Inc. 13G · institution filed 2025-04-23 | 8.2% |
Fell to 5% or below in the last year: Portolan Capital Management, LLC (4.5%, 2026-05-15), VANGUARD GROUP INC (0.0%, 2026-03-26), DIMENSIONAL FUND ADVISORS LP (3.9%, 2026-01-21)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 0 | — | 4 | $3.0m | $3.0m |
| Q1 2025 | 0 | — | 4 | $1.9m | $1.9m |
| Q2 2025 | 0 | — | 1 | $693.7k | $693.7k |
| Q3 2025 | 0 | — | 2 | $1.3m | $927.2k |
| Q4 2025 | 0 | — | 4 | $4.9m | $3.7m |
| Q1 2026 | 0 | — | 4 | $4.1m | $3.9m |
| Q2 2026 | 0 | — | 2 | $1.1m | $1.1m |
| Q3 2026 | 0 | — | 4 | $7.8m | $6.3m |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-09-21 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $303.1k8.6k shares |
| 2026-09-21 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $209.0k5.9k shares |
| 2026-09-15 | Juvenal Tobin W Chief Commercial Officer | Sold plan | $115.8k3.3k shares |
| 2026-09-14 | Juvenal Tobin W Chief Commercial Officer | Sold plan | $106.8k3.3k shares |
| 2026-09-11 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $267.6k8.4k shares |
| 2026-09-11 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold Descendants 2020 Trust | Sold plan | $100.0k3.1k shares |
| 2026-09-11 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By Derek Maetzold 2020 Irrevocable Trust | Sold plan | $85.0k2.7k shares |
| 2026-09-11 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $7.3k223 shares |
| 2026-09-11 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $5.0k154 shares |
| 2026-09-01 | Oelschlager Kristen M Chief Operating Officer | Sold plan | $138.6k4.2k shares |
| 2026-08-31 | Juvenal Tobin W Chief Commercial Officer | Sold plan | $56.8k1.7k shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $380.2k11.5k shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk | Sold plan | $83.0k2.5k shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold | Sold plan | $77.6k2.3k shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $32.4k956 shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold | Sold plan | $14.5k434 shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold | Sold plan | $9.2k278 shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By Derek Maetzold 2020 Irrevocable Trust | Sold plan | $8.5k257 shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold Descendants 2020 Trust | Sold plan | $8.5k257 shares |
| 2026-08-28 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $2.1k63 shares |
| 2026-08-25 | Oelschlager Kristen M Chief Operating Officer · The Fritz Shorter Trust | Sold | $426.3k12.4k shares |
| 2026-08-25 | Juvenal Tobin W Chief Commercial Officer | Sold plan | $317.1k9.1k shares |
| 2026-08-24 | Oelschlager Kristen M Chief Operating Officer · The Fritz Shorter Trust | Sold | $411.6k12.2k shares |
| 2026-08-17 | Juvenal Tobin W Chief Commercial Officer | Sold plan | $51.2k1.7k shares |
| 2026-08-14 | Stokes Frank Chief Financial Officer | Sold | $741.5k24.9k shares |
| 2026-08-14 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk | Sold plan | $81.5k2.7k shares |
| 2026-08-14 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold | Sold plan | $69.2k2.3k shares |
| 2026-08-14 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $33.0k1.1k shares |
| 2026-08-14 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director | Sold plan | $16.7k556 shares |
| 2026-08-14 | MAETZOLD DEREK J Pres. & Chief Exec. Officer, director · By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold | Sold plan | $8.3k278 shares |
The latest 30 of 112 trades.
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 3.3m $78.5m | Added +309.0k |
| RTW INVESTMENTS, LP 0.57% of their portfolio | 2.8m $66.3m | Added +20.0k |
| PRINCIPAL FINANCIAL GROUP INC 0.02% of their portfolio | 1.7m $41.2m | Reduced -43.2k |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 1.2m $29.3m | Added +49.0k |
| ACADIAN ASSET MANAGEMENT LLC 0.03% of their portfolio | 918.7k $21.9m | Added +434.2k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 840.8k $20.1m | Reduced -21.0k |
| SUMMIT PARTNERS PUBLIC ASSET MANAGEMENT, LLC 0.51% of their portfolio | 824.9k $19.7m | Reduced -115.8k |
| STATE STREET CORP 0.00% of their portfolio | 822.1k $19.6m | Added +53.0k |
| Allianz Asset Management GmbH 0.02% of their portfolio | 811.3k $19.9m | Unchanged |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 795.9k $19.0m | Added +67.8k |
| MACKENZIE FINANCIAL CORP 0.02% of their portfolio | 793.5k $18.9m | Added +719.4k |
| DIMENSIONAL FUND ADVISORS LP 0.00% of their portfolio | 791.1k $18.9m | Reduced -248.7k |
| Jefferies Financial Group Inc. 0.14% of their portfolio | 647.4k $15.4m | New |
| Qube Research & Technologies Ltd 0.02% of their portfolio | 589.3k $14.1m | Added +29.7k |
| AIGH Capital Management LLC 1.18% of their portfolio | 545.1k $13.0m | Reduced -45.5k |
| RENAISSANCE TECHNOLOGIES LLC 0.01% of their portfolio | 371.2k $8.9m | Reduced -161.6k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 358.4k $8.5m | Added +17.2k |
| Point72 Asset Management, L.P. 0.01% of their portfolio | 357.3k $8.5m | New |
| KENNEDY CAPITAL MANAGEMENT LLC 0.15% of their portfolio | 348.4k $8.3m | New |
| Connor, Clark & Lunn Investment Management Ltd. 0.01% of their portfolio | 331.7k $7.9m | Reduced -45.4k |
| MORGAN STANLEY 0.00% of their portfolio | 329.7k $7.9m | Reduced -99.2k |
| Portolan Capital Management, LLC 0.29% of their portfolio | 328.8k $7.8m | Reduced -1.0m |
| PANAGORA ASSET MANAGEMENT INC 0.02% of their portfolio | 301.0k $7.2m | Added +78.7k |
| Allspring Global Investments Holdings, LLC 0.01% of their portfolio | 292.5k $7.0m | Added +131.8k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 285.2k $6.8m | Added +12.1k |
| WASATCH ADVISORS LP 0.04% of their portfolio | 279.3k $6.7m | Reduced -175.7k |
| CITADEL ADVISORS LLC 0.00% of their portfolio | 265.4k $6.3m | Added +144.4k |
| KORNITZER CAPITAL MANAGEMENT INC /KS 0.13% of their portfolio | 264.2k $6.3m | Reduced -161 |
| SILVERCREST ASSET MANAGEMENT GROUP LLC 0.04% of their portfolio | 256.1k $6.1m | Reduced -12.4k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 254.5k $6.1m | Added +12.7k |
| Advisors Capital Management, LLC 0.06% of their portfolio | 238.2k $5.7m | Reduced -10.2k |
| NEW YORK STATE COMMON RETIREMENT FUND 0.01% of their portfolio | 234.7k $5.6m | Added +1.7k |
| PALISADE CAPITAL MANAGEMENT, LP 0.24% of their portfolio | 231.9k $5.5m | Reduced -304.0k |
| Nuveen, LLC 0.00% of their portfolio | 231.7k $5.5m | Reduced -290.4k |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.09% of their portfolio | 221.3k $5.3m | Reduced -33.8k |
| Trexquant Investment LP 0.03% of their portfolio | 206.1k $4.9m | Added +75.7k |
| MILLENNIUM MANAGEMENT LLC 0.00% of their portfolio | 205.4k $4.9m | Reduced -147.9k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 197.5k $4.7m | Added +9.3k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 166.6k $4.0m | Added +101.7k |
| FIRST TRUST ADVISORS LP 0.00% of their portfolio | 145.1k $3.5m | New |
| Parkman Healthcare Partners LLC 0.35% of their portfolio | 144.8k $3.5m | Added +18.6k |
| Empowered Funds, LLC 0.02% of their portfolio | 142.3k $3.4m | Added +10.2k |
| HRT FINANCIAL LP 0.01% of their portfolio | 115.9k $2.8m | Added +100.0k |
| D. E. Shaw & Co., Inc. 0.00% of their portfolio | 112.8k $2.7m | Reduced -99.2k |
| Man Group plc 0.00% of their portfolio | 108.8k $2.6m | Added +61.6k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 100.4k $2.4m | Reduced -148.5k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 98.7k $2.4m | Added +30.9k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 98.0k $2.3m | Added +9.4k |
| FRANKLIN RESOURCES INC 0.00% of their portfolio | 97.7k $2.3m | Added +6.8k |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 0.00% of their portfolio | 92.7k $2.2m | Added +65.6k |
| UBS Group AG 0.00% of their portfolio | 89.4k $2.1m | Added +40.2k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 84.8k $2.1m | Reduced -4.0k |
| SummitTX Capital, L.P. 0.05% of their portfolio | 79.0k $1.9m | Added +12.0k |
| SEI INVESTMENTS CO 0.00% of their portfolio | 74.4k $1.8m | Added +39.4k |
| ALGERT GLOBAL LLC 0.02% of their portfolio | 70.5k $1.7m | Added +35.7k |
| Orion Porfolio Solutions, LLC 0.01% of their portfolio | 69.7k $1.7m | Reduced -5.2k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 69.6k $1.7m | Reduced -52.6k |
| AMERICAN CENTURY COMPANIES INC 0.00% of their portfolio | 65.4k $1.6m | Reduced -13.7k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 64.3k $1.5m | Reduced -618 |
| NORGES BANK 0.00% of their portfolio | 60.1k $1.4m | Not comparable |
| FMR LLC 0.00% of their portfolio | 55.9k $1.3m | Added +5.5k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 55.2k $1.3m | Reduced -6.7k |
| Invesco Ltd. 0.00% of their portfolio | 54.9k $1.3m | Reduced -6.1k |
| Swiss National Bank 0.00% of their portfolio | 53.7k $1.3m | Reduced -3.6k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 53.2k $1.3m | Added +15.4k |
| JANE STREET GROUP, LLC 0.00% of their portfolio | 44.8k $1.1m | Added +2.2k |
| XTX Topco Ltd 0.01% of their portfolio | 39.9k $952.2k | Added +19.6k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 39.0k $930.4k | Added +632 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 37.8k $901.6k | Added +10.3k |
| KBC Group NV 0.00% of their portfolio | 36.0k $860.0k | Reduced -890 |
| Y-Intercept (Hong Kong) Ltd 0.02% of their portfolio | 31.9k $761.2k | Added +8.4k |
| HARBOR CAPITAL ADVISORS, INC. 0.05% of their portfolio | 31.7k $757.0k | Added +6.1k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 31.7k $761.4k | Added +22.4k |
| STRS OHIO 0.00% of their portfolio | 30.5k $727.4k | Added +5.5k |
| BARCLAYS PLC 0.00% of their portfolio | 30.3k $723.4k | Added +3.5k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 30.1k $718.8k | Added +6.0k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 29.5k $704.6k | Added +16.7k |
| Engineers Gate Manager LP 0.01% of their portfolio | 29.5k $703.1k | Added +11.2k |
| Inspire Investing, LLC 0.03% of their portfolio | 29.0k $692.8k | Added +8.0k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 27.1k $665.3k | Added +1.8k |
| Universal- Beteiligungs- und Servicegesellschaft mbH 0.00% of their portfolio | 25.2k $601.5k | Reduced -9.2k |
| TRUIST FINANCIAL CORP 0.00% of their portfolio | 23.8k $567.3k | Added +5 |
| Tidal Investments LLC 0.00% of their portfolio | 22.2k $529.1k | New |
| Legal & General Group Plc 0.00% of their portfolio | 20.5k $490.1k | Reduced -2.6k |
| Schonfeld Strategic Advisors LLC 0.00% of their portfolio | 19.9k $475.3k | Reduced -22.5k |
| First Bank & Trust 0.07% of their portfolio | 18.6k $443.4k | Added +2.1k |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 17.7k $421.0k | Unchanged |
| MetLife Investment Management, LLC 0.00% of their portfolio | 17.0k $405.6k | Added +286 |
| Counterpoint Mutual Funds LLC 0.04% of their portfolio | 16.5k $393.8k | New |
| Campbell & CO Investment Adviser LLC 0.02% of their portfolio | 16.5k $393.0k | Reduced -132.3k |
| Quantinno Capital Management LP 0.00% of their portfolio | 16.4k $391.8k | Reduced -29.0k |
| CITIGROUP INC 0.00% of their portfolio | 16.1k $385.0k | Added +12.1k |
| PERKINS CAPITAL MANAGEMENT INC 0.29% of their portfolio | 16.1k $384.9k | Added +725 |
| Diversify Advisory Services, LLC 0.01% of their portfolio | 15.9k $389.4k | New |
| DIVERSIFY WEALTH MANAGEMENT, LLC 0.01% of their portfolio | 15.9k $389.4k | Added +172 |
| Zurcher Kantonalbank (Zurich Cantonalbank) 0.00% of their portfolio | 15.6k $371.6k | Added +551 |
| Jupiter Topco LLC 0.00% of their portfolio | 15.0k $358.2k | First filing |
| TUDOR INVESTMENT CORP ET AL 0.00% of their portfolio | 14.5k $344.9k | Reduced -208.5k |
| LPL Financial LLC 0.00% of their portfolio | 14.2k $339.1k | Added +4.5k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 13.8k $328.8k | Added +109 |