Castle Biosciences CEO sells 28,646 shares in plan
CASTLE BIOSCIENCES INC president and CEO Derek J. Maetzold exercised stock options and sold common shares under a Rule 10b5-1 trading plan adopted on December 3, 2025.
Rhea-AI Filing Summary
CASTLE BIOSCIENCES INC president and CEO Derek J. Maetzold exercised stock options and sold common shares under a Rule 10b5-1 trading plan adopted on December 3, 2025. On July 31 and August 3, 2026 he exercised options covering 17,144 shares at $2.39 per share and sold an aggregate 28,646 shares at weighted-average prices of $30.152 and $30.353, respectively, including sales by The Maetzold Descendants 2020 Trust and the Derek Maetzold 2020 Irrevocable Trust. The options exercised were fully vested, and he continues to report indirect holdings through several family trusts.
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Insights
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Insider Trade Summary 10b5-1
Exercise and sale activity reported; no spread calculated
Exercise and Sale
18 txns
Insider
MAETZOLD DEREK J
Role
Pres. & Chief Exec. Officer
Sold
28,646 shs ($867K)
Approx. gross sale proceeds
$867K
Approx. exercise cost
$41K
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock option (right to buy) F1, F15 | 10,664 | $0.00 | $0.00 |
| Exercise | Common Stock F1 | 10,664 | $2.39 | $25K |
| Sale | Common Stock F1, F6 | 10,664 | $30.353 | $324K |
| Sale | Common Stock F1, F6, F4 | 4,232 | $30.353 | $128K |
| Sale | Common Stock F1, F6, F5 | 3,597 | $30.353 | $109K |
| Exercise | Stock option (right to buy) F1, F15 | 6,480 | $0.00 | $0.00 |
| Exercise | Common Stock F1, F2 | 6,480 | $2.39 | $15K |
| Sale | Common Stock F1, F3 | 6,480 | $30.152 | $195K |
| Sale | Common Stock F1, F3, F4 | 1,983 | $30.152 | $60K |
| Sale | Common Stock F1, F3, F5 | 1,690 | $30.152 | $51K |
| holding | Common Stock F7 | -- | -- | -- |
| holding | Common Stock F8 | -- | -- | -- |
| holding | Common Stock F9 | -- | -- | -- |
| holding | Common Stock F10 | -- | -- | -- |
| holding | Common Stock F2, F11 | -- | -- | -- |
| holding | Common Stock F2, F12 | -- | -- | -- |
| holding | Common Stock F13 | -- | -- | -- |
| holding | Common Stock F2, F14 | -- | -- | -- |
Holdings After Transaction:
Stock option (right to buy) — 61,759 contracts (Direct);
Common Stock — 21,479 shares (Direct);
Common Stock — 31,781 shares (Indirect, By The Maetzold Descendants 2020 Trust);
Common Stock — 27,009 shares (Indirect, By Derek Maetzold 2020 Irrevocable Trust);
Common Stock — 11,812 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk);
Common Stock — 11,812 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold);
Common Stock — 11,812 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold);
Common Stock — 11,812 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold);
Common Stock — 11,963 shares (Indirect, By DJM Grantor Retained Annuity Trust No. 6);
Common Stock — 27,862 shares (Indirect, By DJM Grantor Retained Annuity Trust No. 7);
Common Stock — 40,935 shares (Indirect, By DJM Grantor Retained Annuity Trust No. 8);
Common Stock — 23,216 shares (Indirect, DJM Grantor Retained Annuity Trust No. 9)
Footnotes (15)
- F1. These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025.
- F2. Reflects the July 30, 2026 transfers of 6,755 shares of common stock from DJM Grantor Retained Annuity Trust No. 6 and 16,461 shares from DJM Grantor Retained Annuity Trust No. 7 to the Reporting Person's direct holdings, followed by the transfer of those shares to DJM Grantor Retained Annuity Trust No. 9.
- F3. This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, 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.
- F4. 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.
- F5. Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries.
- F6. This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, 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.
- F7. 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.
- F8. 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.
- F9. 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.
- F10. 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.
- 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. Held by DJM Grantor Retained Annuity Trust No. 8 of which the Reporting Person is the trustee and beneficiary.
- F14. Held by DJM Grantor Retained Annuity Trust No. 9 of which the Reporting Person is the trustee and beneficiary.
- F15. The shares subject to the option are fully vested.
Key Figures
Shares sold: 28,646 shares
Options exercised: 17,144 shares
Option exercise price: $2.3900 per share
+3 more
6 metrics
Shares sold
28,646 shares
Aggregate common shares sold across reported transactions
Options exercised
17,144 shares
Common shares underlying stock options exercised in July–August 2026
Option exercise price
$2.3900 per share
Conversion or exercise price of stock options exercised
Weighted-average sale price (31 Jul 2026)
$30.1520 per share
Weighted-average price for sales executed on July 31, 2026
Weighted-average sale price (3 Aug 2026)
$30.3530 per share
Weighted-average price for sales executed on August 3, 2026
10b5-1 plan adoption date
December 3, 2025
Date the CEO adopted the Rule 10b5-1 trading plan governing these trades
Key Terms
Rule 10b5-1 plan, Grantor Retained Annuity Trust, weighted-average sale price, beneficiaries
4 terms
Rule 10b5-1 plan regulatory
"These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person"
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.
Grantor Retained Annuity Trust financial
"Held by DJM Grantor Retained Annuity Trust No. 6 of which the Reporting Person is the trustee"
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 for the transaction"
beneficiaries financial
"of which the Reporting Person is the trustee and the beneficiaries are specified remainder trusts"
Beneficiaries are the people or organizations designated to receive benefits, such as money or assets, from a financial arrangement like a trust, insurance policy, or retirement plan. They matter to investors because choosing the right beneficiaries ensures that assets are passed on according to their wishes, providing financial security or support to loved ones when needed. Think of beneficiaries as the intended recipients of a gift or inheritance.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What insider transactions did CSTL report for CEO Derek Maetzold?
CASTLE BIOSCIENCES INC (CSTL) reported that CEO Derek Maetzold exercised options and sold shares. He exercised options for 17,144 shares at $2.39 and sold a total of 28,646 common shares on July 31 and August 3, 2026.
Were the Castle Biosciences (CSTL) CEO trades made under a Rule 10b5-1 plan?
Yes. Footnotes state these transactions were made pursuant to a Rule 10b5-1 plan. The plan was adopted on December 3, 2025, indicating the sales and option exercises followed a pre-established trading program.
What stock options did the CSTL CEO exercise in this Form 4?
Derek Maetzold exercised stock options convertible into 17,144 shares of common stock at an exercise price of $2.39 per share. The options are reported as fully vested and carry an expiration date of May 9, 2028 for the underlying grants.
Did family trusts participate in the Castle Biosciences (CSTL) stock sales?
Yes. Reported sales include 4,232 shares held by The Maetzold Descendants 2020 Trust and 3,597 shares held by the Derek Maetzold 2020 Irrevocable Trust, both reported as indirect ownership positions associated with the CEO.
AI-generated analysis. How Rhea-AI works. Not financial advice.
