MAETZOLD DEREK J 4
4 · CASTLE BIOSCIENCES INC · Filed Mar 13, 2026
Research Summary
AI-generated summary of this filing
Castle Biosciences (CSTL) CEO Derek Maetzold Sells Shares
What Happened
Derek J. Maetzold, President, CEO and Director of Castle Biosciences (CSTL), exercised options on March 11, 2026 to acquire 6,226 shares at $2.39 each (cost ~$14,880). He then sold a total of roughly 44,125 shares in open-market transactions on March 11–12, 2026 for aggregate proceeds of approximately $1,132,820. The sales were reported as executed under a Rule 10b5-1 trading plan.
Key Details
- Dates and prices: option exercise on 2026-03-11 (6,226 shares @ $2.39); open-market sales on 2026-03-11 at a weighted avg $26.11 and on 2026-03-12 at a weighted avg $25.28. Reported trade-price ranges were about $24.90–$26.63 across the executions.
- Aggregate sales: ~44,125 shares sold for ~$1,132,820 in total.
- Options: the shares subject to the option were fully vested (footnote F13). The filing also shows a 6,226-share derivative conversion/disposition reported at $0 (reported separately).
- Plan/authorization: sales were made pursuant to a Rule 10b5-1 plan adopted by Maetzold on December 3, 2025 (footnote F1).
- Trust holdings: several holding notes indicate shares are held in family/grantor retained annuity trusts of which Maetzold is trustee or beneficiary (footnotes F3–F12).
- Filing/timeliness: Form 4 was filed March 13, 2026, reporting trades on March 11–12; this appears to be a timely filing under normal Form 4 deadlines.
- Shares owned after transaction: not specified in the provided transaction details.
Context
- This filing shows an option exercise followed by substantial open-market sales under a pre-established 10b5-1 plan. For retail investors, purchases (buys) often signal a stronger positive insider conviction than routine sales; sales executed under 10b5-1 plans are commonly pre-scheduled and may reflect routine liquidity or diversification rather than a change in view about the company.
- The derivative/zero-dollar disposition reported alongside the exercise can reflect net settlement mechanics (e.g., option conversion, withholding or transfer) — the filing lists it but does not provide extra detail on settlement mechanics.
Insider Transaction Report
Form 4
MAETZOLD DEREK J
DirectorPres. & Chief Exec. Officer
Transactions
- Exercise/Conversion
Common Stock
[F1]2026-03-11$2.39/sh+6,226$14,880→ 112,047 total - Sale
Common Stock
[F1][F2]2026-03-11$26.11/sh−17,310$451,947→ 94,737 total - Sale
Common Stock
[F1][F2][F3]2026-03-11$26.11/sh−1,357$35,430→ 51,566 total(indirect: By Trust) - Sale
Common Stock
[F1][F2][F4]2026-03-11$26.11/sh−1,160$30,286→ 43,826 total(indirect: By Trust) - Sale
Common Stock
[F1][F2][F5]2026-03-11$26.11/sh−282$7,363→ 3,336 total(indirect: By Trust) - Sale
Common Stock
[F1][F2][F6]2026-03-11$26.11/sh−279$7,284→ 3,336 total(indirect: By Trust) - Sale
Common Stock
[F1][F2][F7]2026-03-11$26.11/sh−279$7,284→ 3,336 total(indirect: By Trust) - Sale
Common Stock
[F1][F2][F8]2026-03-11$26.11/sh−279$7,284→ 3,336 total(indirect: By Trust) - Sale
Common Stock
[F1][F9]2026-03-12$25.28/sh−23,179$585,942→ 71,558 total - Exercise/Conversion
Stock option (right to buy)
[F1][F13]2026-03-11−6,226→ 14,282 totalExercise: $2.39Exp: 2028-11-11→ Common Stock (6,226 underlying)
Holdings
- 85,959(indirect: By Trust)
Common Stock
[F10] - 18,718(indirect: By Trust)
Common Stock
[F11] - 44,323(indirect: By Trust)
Common Stock
[F12]
Footnotes (13)
- [F1]These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.
- [F10]Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary.
- [F11]Held by DJM Grantor Retained Annuity Trust No. 6 of which the Reporting Person is the trustee and the beneficiaries are The Maetzold 2018 Remainder Trust FBO John Derek Maetzold, The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk, The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold and The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold.
- [F12]Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.
- [F13]The shares subject to the option are fully vested.
- [F2]This transaction was executed in multiple trades at prices ranging from $25.800 to $26.630, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
- [F3]Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries.
- [F4]Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.
- [F5]Held by The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary.
- [F6]Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
- [F7]Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
- [F8]Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary.
- [F9]This transaction was executed in multiple trades at prices ranging from $24.900 to $25.705, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
Signature
/s/ Frank Stokes, Attorney-in-fact|2026-03-13