Form 4: Castle Biosciences CEO Sells Shares Under 10b5-1 Plan

Castle Biosciences' President and CEO, Derek J. Maetzold, sold 830 shares of common stock for a weighted-average price of $40.35 per share under a pre-arranged 10b5-1 plan.

Summary

• Derek J. Maetzold, President and CEO of Castle Biosciences, Inc. (CSTL), reported the sale of 830 shares of common stock.
• The transaction occurred on December 22, 2025, at a weighted-average sale price of $40.35 per share, with individual trades ranging from $40.01 to $40.69.
• The sale was executed pursuant to a Rule 10b5-1 plan, which was adopted by Mr. Maetzold on May 8, 2025.
• Following this transaction, Mr. Maetzold directly beneficially owns 33,530 shares of common stock.
• Indirect beneficial ownership totals 261,372 shares held across various trusts, including The Maetzold Descendants 2020 Trust, Derek Maetzold 2020 Irrevocable Trust, several Maetzold 2018 Remainder Trusts, and DJM Grantor Retained Annuity Trusts No. 5, No. 6, and No. 7.

Sentiment

Score: 5

Explanation: The sale of shares by the CEO is a routine transaction executed under a pre-arranged 10b5-1 plan, which typically indicates personal financial planning rather than a change in outlook for the company. The number of shares sold is a small fraction of the total beneficial ownership.

Negatives

• An insider sale, even if pre-planned, can sometimes be perceived negatively by the market as it reduces the insider's direct stake in the company.

Future Outlook

N/A

Industry Context

This Form 4 filing details a routine insider stock sale by a key executive. Such transactions, especially when executed under a pre-arranged 10b5-1 plan, are generally not indicative of specific company or industry-wide developments but rather personal financial planning.

Related Party Transactions

• Indirect beneficial ownership through The Maetzold Descendants 2020 Trust, where the reporting person's spouse is trustee and spouse/children are beneficiaries.
• Indirect beneficial ownership through Derek Maetzold 2020 Irrevocable Trust, where the reporting person is trustee and his children are beneficiaries.
• Indirect beneficial ownership through The Maetzold 2018 Remainder Trusts FBO Emily Carol Kirk, Hannah Elizabeth Maetzold, John Derek Maetzold, and Peter Douglas Maetzold, where the reporting person is trustee and his children are beneficiaries.
• Indirect beneficial ownership through DJM Grantor Retained Annuity Trust No. 5 and No. 7, where the reporting person is trustee and beneficiary.
• Indirect beneficial ownership through DJM Grantor Retained Annuity Trust No. 6, where the reporting person is trustee and the beneficiaries are various Maetzold 2018 Remainder Trusts.

Stakeholder Impact

• Shareholders: A minor reduction in direct insider ownership, but overall beneficial ownership remains substantial. The pre-planned nature of the sale mitigates negative signaling.

Key Dates

Recommendation

The reported transaction is a routine insider sale executed under a pre-arranged 10b5-1 plan, which is typically for personal financial management and not indicative of a change in the company's fundamental outlook. The number of shares sold represents a small portion of the CEO's total beneficial ownership. Therefore, this filing alone does not provide sufficient new information to warrant a change in investment thesis, suggesting a 'hold' recommendation based solely on this report.

Keywords

Castle Biosciences, CSTL, Derek J. Maetzold, Insider Trading, Form 4, Stock Sale, CEO, 10b5-1 Plan, Equity Transaction