Castle Biosciences CEO sells 8,580 shares
The transactions were made under a Rule 10b5-1 plan adopted June 2, 2026.
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Form Type
4
Rhea-AI Filing Summary
Castle Biosciences Inc. (CSTL) President and CEO Derek J. Maetzold exercised fully vested options for 8,580 common shares on September 21, 2026, at an exercise price of $2.39 per share, then sold those shares at a weighted-average $35.334 per share. The Maetzold Descendants 2020 Trust sold 3,198 shares and the Derek Maetzold 2020 Irrevocable Trust sold 2,718 shares, each at the same weighted-average price. The transactions were made under a Rule 10b5-1 plan adopted June 2, 2026.
Insider Trade Summary 10b5-1
Exercise and sale activity reported; no spread calculated
Exercise and Sale
5 txns
Insider
MAETZOLD DEREK J
Role
Pres. & Chief Exec. Officer
Sold
14,496 shs ($512K)
Approx. gross sale proceeds
$512K
Approx. exercise cost
$21K
Share of Position Sold
25.5%
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock option (right to buy) F1, F13 | 8,580 | $0.00 | $0.00 |
| Exercise | Common Stock F1 | 8,580 | $2.39 | $21K |
| Sale | Common Stock F1, F2 | 8,580 | $35.334 | $303K |
| Sale | Common Stock F1, F2, F3 | 3,198 | $35.334 | $113K |
| Sale | Common Stock F1, F2, F4 | 2,718 | $35.334 | $96K |
| Holding | Common Stock F5 | -- | -- | -- |
| Holding | Common Stock F6 | -- | -- | -- |
| Holding | Common Stock F7 | -- | -- | -- |
| Holding | Common Stock F8 | -- | -- | -- |
| Holding | Common Stock F9 | -- | -- | -- |
| Holding | Common Stock F10 | -- | -- | -- |
| Holding | Common Stock F11 | -- | -- | -- |
| Holding | Common Stock F12 | -- | -- | -- |
Holdings After Transaction:
Stock option (right to buy) — 8,165 options (Direct);
Common Stock — 21,479 shares (Direct);
Common Stock — 11,236 shares (Indirect, By The Maetzold Descendants 2020 Trust);
Common Stock — 9,550 shares (Indirect, By Derek Maetzold 2020 Irrevocable Trust);
Common Stock — 11,256 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk);
Common Stock — 11,256 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold);
Common Stock — 11,256 shares (Indirect, By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold);
Common Stock — 11,256 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)
Holdings Before and After:
Stock option (right to buy), 16,745 to 8,165 options (Direct);
Common Stock, 21,479 to 21,479 shares (Direct);
Common Stock, 14,434 to 11,236 shares (Indirect, By The Maetzold Descendants 2020 Trust);
Common Stock, 12,268 to 9,550 shares (Indirect, By Derek Maetzold 2020 Irrevocable Trust)
Other Insiders: 2 other insiders reported open-market sales of this stock in the 30 days up to this filing.
Footnotes (13)
- F1. These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on June 2, 2026.
- F2. This transaction was executed in multiple trades at prices ranging from $35.020 to $35.665, 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. 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.
- F10. Held by DJM Grantor Retained Annuity Trust No. 7 of which the Reporting Person is the trustee and beneficiary.
- F11. Held by DJM Grantor Retained Annuity Trust No. 8 of which the Reporting Person is the trustee and beneficiary.
- F12. Held by DJM Grantor Retained Annuity Trust No. 9 of which the Reporting Person is the trustee and beneficiary.
- F13. The shares subject to the option are fully vested.
Key Figures
Options exercised: 8,580 options
Exercise price: $2.39 per share
Direct common-stock sale: 8,580 shares at weighted-average $35.334 per share
+4 more
7 metrics
Options exercised
8,580 options
Fully vested options exercised for common shares on September 21, 2026
Exercise price
$2.39 per share
Options exercised on September 21, 2026
Direct common-stock sale
8,580 shares at weighted-average $35.334 per share
Derek J. Maetzold; September 21, 2026
Maetzold Descendants 2020 Trust sale
3,198 shares at weighted-average $35.334 per share
September 21, 2026
Derek Maetzold 2020 Irrevocable Trust sale
2,718 shares at weighted-average $35.334 per share
September 21, 2026
Options following exercise
8,165 options
Reported after the exercise on September 21, 2026
Post-sale trust holdings
11,236 shares; 9,550 shares
The Maetzold Descendants 2020 Trust; Derek Maetzold 2020 Irrevocable Trust, respectively
Key Terms
Rule 10b5-1 plan, weighted-average sale price, fully vested
3 terms
Rule 10b5-1 plan regulatory
"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.
weighted-average sale price financial
"price reported above reflects the weighted-average sale price"
fully vested financial
"shares subject to the option are fully vested"
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
How many CSTL options did Derek J. Maetzold exercise, and at what price?
He exercised fully vested options for 8,580 common shares on September 21, 2026, at an exercise price of $2.39 per share. The option transaction reported 8,165 options following the exercise.
AI-generated analysis. How Rhea-AI works. Not financial advice.
