Castle Biosciences CEO sells 14.5K shares
CASTLE BIOSCIENCES INC (CSTL) reported insider activity by President & Chief Executive Officer Derek J. Maetzold.
Rhea-AI Filing Summary
CASTLE BIOSCIENCES INC (CSTL) reported insider activity by President & Chief Executive Officer Derek J. Maetzold. On September 11, 2026, he exercised options for 8,584 shares of common stock at $2.39 per share and, on the same date, entities associated with him sold a total of 14,518 shares of common stock in open-market transactions at prices including $32.00 and $32.78 per share. The option shares were fully vested, and the company reports that these transactions were made under a Rule 10b5-1 trading plan adopted on June 2, 2026.
Positive
- None.
Negative
- None.
Insider Trade Summary 10b5-1
Exercise and sale activity reported; no spread calculated
Exercise and Sale
16 txns
Insider
MAETZOLD DEREK J
Role
Pres. & Chief Exec. Officer
Sold
14,518 shs ($465K)
Approx. gross sale proceeds
$465K
Approx. exercise cost
$21K
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock option (right to buy) F1, F13 | 8,584 | $0.00 | $0.00 |
| Exercise | Common Stock F1 | 8,584 | $2.39 | $21K |
| Sale | Common Stock F1, F2 | 8,361 | $32.00 | $268K |
| Sale | Common Stock F1, F2, F3 | 3,124 | $32.00 | $100K |
| Sale | Common Stock F1, F2, F4 | 2,656 | $32.00 | $85K |
| Sale | Common Stock F1 | 223 | $32.78 | $7K |
| Sale | Common Stock F1, F3 | 83 | $32.78 | $3K |
| Sale | Common Stock F1, F4 | 71 | $32.78 | $2K |
| 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) — 16,745 contracts (Direct);
Common Stock — 21,479 shares (Direct);
Common Stock — 14,434 shares (Indirect, By The Maetzold Descendants 2020 Trust);
Common Stock — 12,268 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)
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 $31.700 to $32.508, 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: 8,584 shares
Option exercise price: $2.39 per share
Shares sold: 14,518 shares
+4 more
7 metrics
Options exercised
8,584 shares
Stock option exercise into common stock on September 11, 2026
Option exercise price
$2.39 per share
Exercise price for 8,584 options exercised on September 11, 2026
Shares sold
14,518 shares
Total CSTL common shares sold in open-market transactions on September 11, 2026
Reported sale prices
$32.00 and $32.78 per share
Per-share sale prices for CSTL stock; trades occurred in a $31.700–$32.508 range
Remaining option shares
16,745 shares
Option shares reported as outstanding after the 8,584-share exercise
Trust holding (example)
11,256 shares
Common stock held by each Maetzold 2018 Remainder Trust FBO named beneficiaries
Largest GRAT holding
40,935 shares
CSTL common stock held by DJM Grantor Retained Annuity Trust No. 8
Key Terms
Rule 10b5-1 plan, weighted-average sale price, Grantor Retained Annuity Trust, beneficiaries, +1 more
5 terms
Rule 10b5-1 plan regulatory
"These transactions were made pursuant to a Rule 10b5-1 plan adopted"
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
"The price reported above reflects the weighted-average sale price"
Grantor Retained Annuity Trust financial
"Held by DJM Grantor Retained Annuity Trust No. 7 of which"
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.
beneficiaries financial
"of which the Reporting Person is the trustee and the beneficiaries are"
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.
derivative security financial
"Exercise or conversion of derivative security"
A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What did CSTL’s CEO do in this Form 4 transaction?
Derek J. Maetzold, CEO of CSTL, exercised options for 8,584 shares of common stock at $2.39 per share and related accounts sold a total of 14,518 shares of common stock in open-market transactions on September 11, 2026.
Were the CSTL insider transactions made under a Rule 10b5-1 plan?
Yes. A footnote states the transactions were made pursuant to a Rule 10b5-1 plan adopted by Derek J. Maetzold on June 2, 2026, and the filing’s Rule 10b5-1 checkbox is marked as affirming a trading plan.
How many CSTL options did the CEO exercise and what remains?
The CEO exercised options covering 8,584 shares of CSTL common stock at an exercise price of $2.39 per share. After this exercise, 16,745 option shares remain reported for this option series, which is fully vested and expires on May 9, 2028.
AI-generated analysis. How Rhea-AI works. Not financial advice.
