Comparable stake leader
RTW INVESTMENTS, LP
SEC ownership of CASTLE BIOSCIENCES INC
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001447362.
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
30 Jun 2026
- Public ticker
- CSTL on Nasdaq
- Parsed ownership sources
-
13D/G and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
RTW INVESTMENTS, LP
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
RTW INVESTMENTS, LP
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
30 Jun 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001447362
- Issuer location
- Friendswood, TX
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of CASTLE BIOSCIENCES INC (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
RTW INVESTMENTS, LP
Disclosed value leader
BlackRock, Inc.
Comparable rows
50/50
Latest evidence
30 Jun 2026
13D/G
13F
Lead comparable stake: 9.3%
13D/G row: RTW INVESTMENTS, LP
Showing 1-8 of 50 holder rows.
Quick read
RTW INVESTMENTS, LP leads the comparable SEC ownership view at 9.3%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens RTW INVESTMENTS, LP's linked filing trail.
Comparable ownership
Top 5
RTW INVESTMENTS, LP
9.3%
BlackRock, Inc.
8.2%
Portolan Capital Management, LLC
4.4%
DIMENSIONAL FUND ADVISORS LP
3.9%
WASATCH ADVISORS LP
3.5%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| RTW INVESTMENTS, LP |
13D/G
13F
Company
|
9.3%
|
$67,717,124
2,758,335 shares
|
+$15,788,056 | 31 Mar 2026 |
| BlackRock, Inc. |
13F
13D/G
Company
|
8.2%
from 13D/G
|
$78,513,319
3,291,963 shares
|
— | 30 Jun 2026 |
| Portolan Capital Management, LLC |
13D/G
13F
Company
|
4.4%
|
$33,149,448
1,350,283 shares
|
-$6,403,033 | 31 Mar 2026 |
| DIMENSIONAL FUND ADVISORS LP |
13D/G
13F
Company
|
3.9%
|
$44,494,010
1,143,799 shares
|
-$12,848,347 | 31 Dec 2025 |
| WASATCH ADVISORS LP |
13D/G
13F
Company
|
3.5%
|
$20,078,930
998,455 shares
|
$0 | 31 Mar 2025 |
| PRINCIPAL FINANCIAL GROUP INC |
13F
Company
|
5.7%
|
$41,180,555
1,726,648 shares
|
— | 30 Jun 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13F
Company
|
4%
|
$29,251,953
1,226,497 shares
|
— | 30 Jun 2026 |
| ACADIAN ASSET MANAGEMENT LLC |
13F
Company
|
3%
|
$21,897,000
918,668 shares
|
— | 30 Jun 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Net insider flow leans to selling over the last 12 months. Net value: -$15,302,673.
Buys
$0
Insiders: 0
Sells
$15,302,673
Insiders: 5
Net
-$15,302,673
Shares: -522,658
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 522,658
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 184,183 | $0 | $5,152,335 | -$5,152,335 |
| 3-6 | 0 | 167,659 | $0 | $4,282,092 | -$4,282,092 |
| 6-9 | 0 | 86,595 | $0 | $3,358,218 | -$3,358,218 |
| 9-12 | 0 | 84,221 | $0 | $2,510,029 | -$2,510,029 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-14 of 14 reporting-owner rows connected to CASTLE BIOSCIENCES INC. Open a relationship link for the CIK-to-CIK filing trail.
Rows
14
Largest Forms 3/4/5 holder
Derek J. Maetzold
Net 12M change
-$15,302,672
Latest report
17 Aug 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Derek J. Maetzold | Pres. & Chief Exec. Officer, Director | $11,494,354 | -$9,161,743 | -44% | Mixed | 14 Aug 2026 |
| KABAKOFF DAVID S | Director | $10,282,139 | Mixed | 17 Jun 2021 | ||
| Kristen M. Oelschlager | Chief Operating Officer | $3,875,974 | -$2,600,943 | -40% | Mixed | 03 Aug 2026 |
| Tobin W. Juvenal | Chief Commercial Officer | $3,454,305 | -$1,870,381 | -35% | Mixed | 17 Aug 2026 |
| Frank Stokes | Chief Financial Officer | $2,284,750 | -$1,458,878 | -39% | Mixed | 14 Aug 2026 |
| Mara G. Aspinall | Director | $1,101,224 | Mixed | 23 May 2024 | ||
| Rodney Cotton | Director | $1,018,142 | Mixed | 28 May 2026 | ||
| Ellen Goldberg | Director | $1,004,610 | Mixed | 28 May 2026 | ||
| Tiffany Olson | Director | $984,087 | Mixed | 28 May 2026 | ||
| Kim Caple | Director | $886,770 | Mixed | 28 May 2026 | ||
| Miles Harrison | Director | $874,741 | Mixed | 28 May 2026 | ||
| Daniel Bradbury | Director | $874,741 | Mixed | 28 May 2026 | ||
| G. Bradley Cole | Director | $809,560 | -$210,727 | -21% | Mixed | 28 May 2026 |
| Bernhard E. Spiess | Chief Business Officer | $389,976 | Mixed | 10 Dec 2021 |
Recent insider transactions for CASTLE BIOSCIENCES INC
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Tobin W. Juvenal | CSTL | Common Stock | Sale | -2.23% | $51,191 | $29.59 | -1,730 | 75,964 | 17 Aug 2026 | Direct |
| Frank Stokes | CSTL | Common Stock | Sale | -41.4% | $741,511 | $29.77 | -24,908 | 35,177 | 14 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.35% | $8,346 | $30.02 | -278 | 11,534 | 14 Aug 2026 | By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.35% | $8,346 | $30.02 | -278 | 11,534 | 14 Aug 2026 | By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.35% | $8,346 | $30.02 | -278 | 11,534 | 14 Aug 2026 | By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.35% | $8,346 | $30.02 | -278 | 11,534 | 14 Aug 2026 | By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -11.8% | $69,226 | $30.02 | -2,306 | 17,301 | 14 Aug 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -11.8% | $81,474 | $30.02 | -2,714 | 20,355 | 14 Aug 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -4.87% | $33,022 | $30.02 | -1,100 | 21,479 | 14 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 5.12% | 1,100 | 22,579 | 14 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -2.83% | -1,100 | 37,757 | 14 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.36% | $14,512 | $30.68 | -473 | 19,607 | 05 Aug 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.35% | $17,059 | $30.68 | -556 | 23,069 | 05 Aug 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -10.6% | $78,114 | $30.68 | -2,546 | 21,479 | 05 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 11.8% | 2,546 | 24,025 | 05 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -6.15% | -2,546 | 38,857 | 05 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Common Stock | Sale | -25.6% | $215,557 | $31.11 | -6,929 | 20,080 | 04 Aug 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -25.7% | $253,727 | $31.11 | -8,156 | 23,625 | 04 Aug 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -48.7% | $633,261 | $31.11 | -20,356 | 21,479 | 04 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 94.8% | 20,356 | 41,835 | 04 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -33% | -20,356 | 41,403 | 04 Aug 2026 | Direct | ||
| Kristen M. Oelschlager | CSTL | Common Stock | Sale | -39.2% | $255,622 | $29.77 | -8,586 | 13,288 | 03 Aug 2026 | Direct |
| Tobin W. Juvenal | CSTL | Common Stock | Sale | -2.14% | $48,872 | $28.25 | -1,730 | 78,995 | 03 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -11.8% | $109,180 | $30.35 | -3,597 | 27,009 | 03 Aug 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -11.8% | $128,454 | $30.35 | -4,232 | 31,781 | 03 Aug 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -33.2% | $323,684 | $30.35 | -10,664 | 21,479 | 03 Aug 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 49.6% | 10,664 | 32,143 | 03 Aug 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -14.7% | -10,664 | 61,759 | 03 Aug 2026 | Direct | ||
| Tobin W. Juvenal | CSTL | Common Stock | Sale | -17.7% | $507,302 | $29.31 | -17,310 | 80,725 | 31 Jul 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -5.23% | $50,957 | $30.15 | -1,690 | 30,606 | 31 Jul 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -5.22% | $59,791 | $30.15 | -1,983 | 36,013 | 31 Jul 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -23.2% | $195,385 | $30.15 | -6,480 | 21,479 | 31 Jul 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 30.2% | 6,480 | 27,959 | 31 Jul 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -8.21% | -6,480 | 72,423 | 31 Jul 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.3% | $6,717 | $24.16 | -278 | 11,812 | 27 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.3% | $6,717 | $24.16 | -278 | 11,812 | 27 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.3% | $6,717 | $24.16 | -278 | 11,812 | 27 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.3% | $6,717 | $24.16 | -278 | 11,812 | 27 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -3.45% | $27,862 | $24.16 | -1,153 | 32,296 | 27 Jul 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -3.45% | $32,791 | $24.16 | -1,357 | 37,996 | 27 Jul 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -22.4% | $150,160 | $24.16 | -6,214 | 21,479 | 27 Jul 2026 | Direct |
| Derek J. Maetzold | CSTL | Common Stock | Options Exercise | 28.9% | 6,214 | 27,693 | 27 Jul 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Stock option (right to buy) | Options Exercise | -7.3% | -6,214 | 78,903 | 27 Jul 2026 | Direct | ||
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.25% | $6,372 | $22.92 | -278 | 12,090 | 14 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.25% | $6,372 | $22.92 | -278 | 12,090 | 14 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.25% | $6,372 | $22.92 | -278 | 12,090 | 14 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.25% | $6,372 | $22.92 | -278 | 12,090 | 14 Jul 2026 | By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -3.33% | $26,427 | $22.92 | -1,153 | 33,449 | 14 Jul 2026 | By Derek Maetzold 2020 Irrevocable Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -3.33% | $31,102 | $22.92 | -1,357 | 39,353 | 14 Jul 2026 | By The Maetzold Descendants 2020 Trust |
| Derek J. Maetzold | CSTL | Common Stock | Sale | -2.5% | $12,606 | $22.92 | -550 | 21,479 | 14 Jul 2026 | Direct |
* marks a reported price that did not pass the local price check.