Castle Biosciences (CSTL) CEO sells 9,836 shares via 10b5-1 plan
Filing Impact
Filing Sentiment
Form Type
4
Rhea-AI Filing Summary
Castle Biosciences CEO Derek Maetzold reported option exercises and share sales in Castle Biosciences Inc. common stock. On July 1, 2026, he exercised options for 6,214 shares at $2.39 per share and related entities sold a combined 9,836 shares in open-market transactions at a weighted-average price of $24.29, pursuant to a pre-arranged Rule 10b5-1 plan.
Following these transactions, one direct holding shows 21,479 shares of common stock, and various family and grantor retained annuity trusts associated with Maetzold continue to hold additional indirect positions.
Positive
- None.
Negative
- None.
Insights
Pre-planned option exercise with routine net share sale.
Derek Maetzold, CEO of Castle Biosciences, exercised options for 6,214 shares at $2.39 and entities associated with him sold 9,836 shares at a weighted-average price of $24.29 on July 1, 2026.
The filing states these sales were made under a pre-arranged Rule 10b5-1 plan, which typically indicates a scheduled, systematic approach rather than discretionary market timing. After the sale, one direct account shows 21,479 common shares, while several trusts continue to hold sizable indirect stakes.
This pattern—exercise of fully vested options and partial monetization through planned sales—appears routine and does not, by itself, signal a major change in insider conviction. The absence of remaining derivative positions in this filing suggests those particular options have been fully exercised.
Insider Trade Summary 10b5-1
Net Seller: 9,836 shares ($238,916)
Net Sell
12 txns
Insider
MAETZOLD DEREK J
Role
Pres. & Chief Exec. Officer
Sold
9,836 shs ($239K)
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Exercise | Stock option (right to buy) | 6,214 | $0.00 | -- |
| Exercise | Common Stock | 6,214 | $2.39 | $15K |
| Sale | Common Stock | 6,214 | $24.29 | $151K |
| Sale | Common Stock | 1,357 | $24.29 | $33K |
| Sale | Common Stock | 1,153 | $24.29 | $28K |
| Sale | Common Stock | 278 | $24.29 | $7K |
| Sale | Common Stock | 278 | $24.29 | $7K |
| Sale | Common Stock | 278 | $24.29 | $7K |
| Sale | Common Stock | 278 | $24.29 | $7K |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
Holdings After Transaction:
Stock option (right to buy) — 85,667 shares (Direct, null);
Common Stock — 27,693 shares (Direct, null);
Common Stock — 40,710 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 $23.68 to $24.57, 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. 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. Held by DJM Grantor Retained Annuity Trust No. 8 of which the Reporting Person is the trustee and beneficiary. The shares subject to the option are fully vested.
Key Figures
Shares sold: 9,836 shares
Sale price: $24.29 per share
Options exercised: 6,214 shares
+5 more
8 metrics
Shares sold
9,836 shares
Open-market sales on July 1, 2026
Sale price
$24.29 per share
Weighted-average sale price for common stock
Options exercised
6,214 shares
Common stock acquired via option exercise
Option exercise price
$2.39 per share
Exercise price of stock option
Direct common shares after
21,479 shares
Direct holding following transactions
Remaining options
85,667 options
Stock option balance after exercise
Sale date
July 1, 2026
Trade and exercise date reported in Form 4
Option expiration
May 9, 2028
Expiration date of the exercised option grant
Key Terms
Rule 10b5-1 plan, Grantor Retained Annuity Trust, stock option (right to buy), weighted-average sale price, +1 more
5 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.
stock option (right to buy) financial
"security_title": "Stock option (right to buy)""
weighted-average sale price financial
"executed in multiple trades at prices ranging from $23.68 to $24.57, inclusive. The price reported above reflects the weighted-average sale price."
beneficiaries financial
"of which the Reporting Person is the trustee and his children are beneficiaries."
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
What insider transactions did CSTL CEO Derek Maetzold report on July 1, 2026?
On July 1, 2026, entities associated with CSTL CEO Derek Maetzold sold 9,836 shares of Castle Biosciences common stock and he exercised options for 6,214 shares at $2.39. The sales occurred at a weighted-average price of $24.29 per share.
What stock options did Derek Maetzold exercise in this CSTL Form 4?
He exercised fully vested stock options covering 6,214 Castle Biosciences shares at an exercise price of $2.39 per share. A related derivative table shows 85,667 stock options remaining after the exercise, with an expiration date of May 9, 2028 for that option grant.