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

Castle Biosciences President and CEO Derek J. Maetzold sold 32,346 shares of common stock in December 2025 through a pre-arranged Rule 10b5-1 trading plan.

Summary

• Derek J. Maetzold, President and Chief Executive Officer, and a Director of Castle Biosciences Inc. (CSTL), disposed of a total of 32,346 shares of common stock.
• The transactions occurred on December 15, 2025, and December 16, 2025.
• These sales were executed pursuant to a Rule 10b5-1 plan adopted by Mr. Maetzold on May 8, 2025.
• On December 15, 2025, 18,513 shares were sold at a weighted-average price of $38.747 per share, with trades ranging from $38.240 to $39.220.
• Also on December 15, 2025, an additional 1,012 shares were sold at a weighted-average price of $39.304 per share, with trades ranging from $39.240 to $39.390.
• On December 16, 2025, 12,821 shares were sold at a weighted-average price of $38.554 per share, with trades ranging from $38.135 to $39.070.
• Following these transactions, Mr. Maetzold directly beneficially owns 34,869 shares of common stock.
• Mr. Maetzold also indirectly beneficially owns 261,372 shares through 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, 6, and 7.

Sentiment

Score: 5

Explanation: The sentiment is neutral. While insider selling can be perceived negatively, the transactions were conducted under a pre-arranged Rule 10b5-1 plan, suggesting they are part of a personal financial strategy rather than a reaction to new adverse company developments. This mitigates the negative signal typically associated with insider sales.

Positives

• The sales were conducted under a pre-arranged Rule 10b5-1 trading plan, which indicates the transactions were scheduled in advance and not based on new, non-public information, potentially mitigating concerns about the timing of the sales.

Negatives

• Insider selling, even when pre-planned, can sometimes be perceived negatively by investors as it reduces the direct ownership stake of a key executive in the company.
• The total value of shares sold by the CEO exceeds $1.25 million, representing a significant divestment.

Risks

• Investor sentiment could be negatively impacted by the perception of insider selling, potentially leading to short-term downward pressure on the stock price.

Future Outlook

na

Industry Context

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Related Party Transactions

• Derek J. Maetzold, the reporting person, holds indirect beneficial ownership through several trusts where he or his family members serve as trustees or beneficiaries. These include The Maetzold Descendants 2020 Trust, Derek Maetzold 2020 Irrevocable Trust, The Maetzold 2018 Remainder Trusts (FBO Emily Carol Kirk, Hannah Elizabeth Maetzold, John Derek Maetzold, Peter Douglas Maetzold), and DJM Grantor Retained Annuity Trusts No. 5, 6, and 7.

Stakeholder Impact

• Shareholders may interpret the insider selling as a signal, potentially influencing their investment decisions and leading to short-term fluctuations in the stock price.
• The reduction in direct ownership by the CEO could be viewed by some as a decrease in alignment of interests, although the pre-planned nature of the sales lessens this concern.

Key Dates

Recommendation

The sales by the CEO were conducted under a pre-arranged Rule 10b5-1 plan, indicating they are part of a personal financial strategy rather than a reaction to new company-specific information. While insider selling can be perceived negatively, the planned nature mitigates concerns about immediate adverse company developments. Investors should monitor future filings and company performance for further insights, but this specific transaction alone does not warrant a change from a 'hold' position.

Keywords

Castle Biosciences, CSTL, Form 4, Insider Trading, Stock Sale, CEO, Derek Maetzold, 10b5-1 Plan, Beneficial Ownership