Castle Biosciences (CSTL) CEO executes 10b5-1 share sales, exercises options
Filing Impact
Filing Sentiment
Form Type
4
Rhea-AI Filing Summary
Castle Biosciences (CSTL) President and CEO Derek J. Maetzold reported exercising stock options and selling shares in a pre-planned transaction. He exercised options for 550 shares of common stock at $2.39 per share, then sold a total of 4,172 common shares at a weighted-average price of $25.551 per share under a Rule 10b5-1 trading plan.
After these transactions, Maetzold holds 21,479 common shares directly and 13,732 options, with additional indirect holdings through several family trusts, including 50,209 shares in The Maetzold Descendants 2020 Trust and 42,673 shares in the Derek Maetzold 2020 Irrevocable Trust.
Positive
- None.
Negative
- None.
Insider Trade Summary 10b5-1
Net Seller: 4,172 shares ($106,599)
Net Sell
12 txns
Insider
MAETZOLD DEREK J
Role
Pres. & Chief Exec. Officer
Sold
4,172 shs ($107K)
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock option (right to buy) | 550 | $0.00 | -- |
| Exercise | Common Stock | 550 | $2.39 | $1K |
| Sale | Common Stock | 550 | $25.551 | $14K |
| Sale | Common Stock | 1,357 | $25.551 | $35K |
| Sale | Common Stock | 1,153 | $25.551 | $29K |
| Sale | Common Stock | 278 | $25.551 | $7K |
| Sale | Common Stock | 278 | $25.551 | $7K |
| Sale | Common Stock | 278 | $25.551 | $7K |
| Sale | Common Stock | 278 | $25.551 | $7K |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
Holdings After Transaction:
Stock option (right to buy) — 13,732 shares (Direct);
Common Stock — 22,029 shares (Direct);
Common Stock — 50,209 shares (Indirect, By The Maetzold Descendants 2020 Trust)
Footnotes (1)
- These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. This transaction was executed in multiple trades at prices ranging from $25.050 to $25.955, 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. 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. Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries. 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. 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. 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. 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. Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary. 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. Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary. The shares subject to the option are fully vested.
Key Figures
Options exercised: 550 shares at $2.39
Shares sold: 4,172 shares at $25.551
Direct common shares after: 21,479 shares
+4 more
7 metrics
Options exercised
550 shares at $2.39
Stock option exercise into common stock
Shares sold
4,172 shares at $25.551
Weighted-average sale price for open-market sales
Direct common shares after
21,479 shares
Direct CSTL holdings following transactions
Options remaining
13,732 options
Stock options held after the 550-share exercise
Descendants 2020 Trust holding
50,209 shares
Common shares held by The Maetzold Descendants 2020 Trust
Irrevocable Trust holding
42,673 shares
Common shares held by Derek Maetzold 2020 Irrevocable Trust
DJM GRAT No. 5 holding
85,959 shares
Common shares held by DJM Grantor Retained Annuity Trust No. 5
Key Terms
Rule 10b5-1 plan, stock option (right to buy), Grantor Retained Annuity Trust, weighted-average sale price, +1 more
5 terms
Rule 10b5-1 plan financial
"These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025."
A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.
stock option (right to buy) financial
"security_title: Stock option (right to buy) ... conversion_or_exercise_price: 2.3900"
Grantor Retained Annuity Trust financial
"Held by DJM Grantor Retained Annuity Trust No. 5 of which the Reporting Person is the trustee and beneficiary."
A grantor retained annuity trust (GRAT) is an estate-planning tool where the person who creates the trust transfers assets into it but receives fixed cash payments (an annuity) from the trust for a set number of years; whatever remains after that term passes to designated beneficiaries. It matters to investors because it can shift future appreciation of assets out of the creator’s taxable estate—like putting an asset into a timed vending machine that pays you fixed amounts while any extra value that grows inside the machine goes to heirs with reduced gift or estate tax consequences.
weighted-average sale price financial
"The price reported above reflects the weighted-average sale price."
fully vested financial
"The shares subject to the option are fully vested."
FAQ
What insider transactions did CSTL CEO Derek Maetzold report on this Form 4?
Derek Maetzold reported exercising options for 550 Castle Biosciences shares at $2.39 and selling 4,172 common shares at a weighted-average $25.551. The filing also updates his remaining direct and trust-held share positions following these transactions.
What indirect Castle Biosciences holdings are associated with Derek Maetzold’s family trusts?
The filing lists several family trusts holding CSTL shares, including 50,209 shares in The Maetzold Descendants 2020 Trust and 42,673 shares in the Derek Maetzold 2020 Irrevocable Trust, plus multiple 2018 remainder trusts and three DJM Grantor Retained Annuity Trusts.
Did Derek Maetzold retain stock options in CSTL after this option exercise?
Yes. After exercising options for 550 shares at a $2.39 strike price, Derek Maetzold still holds 13,732 stock options. The filing indicates the option shares involved in this transaction were fully vested at the time of exercise.