Derek J. Maetzold, President and Chief Executive Officer of Castle Biosciences Inc., filed a Form 4 on September 15, 2026, disclosing stock option exercises and common stock sales executed on September 11, 2026, pursuant to a Rule 10b5-1 plan.

Key Highlights

  • Option exercise: Maetzold exercised 8,584 fully vested stock options at an exercise price of $2.39 per share on September 11, 2026.
  • Direct share sales: He disposed of 8,361 shares at a weighted-average price of $32 (ranging from $31.700 to $32.508) and 223 shares at $32.78, all directly held.
  • Trust share sales: Shares held through The Maetzold Descendants 2020 Trust and Derek Maetzold 2020 Irrevocable Trust were also sold on the same date at the same prices.
  • Post-transaction direct ownership: Following all reported transactions, Maetzold directly held 21,479 shares of common stock.
  • Remaining options: After the exercise, Maetzold holds 16,745 stock options directly, with an expiration date of May 9, 2028.
  • 10b5-1 plan: All transactions were made pursuant to a Rule 10b5-1 plan adopted by the reporting person on June 2, 2026.

Maetzold's September 2026 Option Exercise and Share Sales at Castle Biosciences

According to the filing, Derek J. Maetzold, who serves as President and Chief Executive Officer and is also identified as a Director of Castle Biosciences Inc. (NASDAQ:CSTL), executed a series of transactions on September 11, 2026. He first exercised 8,584 stock options at a conversion price of $2.39, acquiring an equivalent number of common shares. The filing notes those options were fully vested and would have expired May 9, 2028. The exercise left Maetzold with 16,745 stock options remaining.

Maetzold then sold shares both directly and through trusts. Direct sales totaled 8,361 shares at a weighted-average price of $32 (executed across multiple trades from $31.700 to $32.508, inclusive) and 223 shares at $32.78. Concurrent indirect sales were executed through The Maetzold Descendants 2020 Trust (3,124 shares at $32 and 83 shares at $32.78) and Derek Maetzold 2020 Irrevocable Trust (2,656 shares at $32 and 71 shares at $32.78). The filing notes that the Descendants 2020 Trust is administered by his spouse as trustee, while the Irrevocable Trust names Maetzold himself as trustee with his children as beneficiaries.

The filing also lists several additional indirectly held positions with no reported transactions, including shares held across four Maetzold 2018 Remainder Trusts (11,256 shares each) and four DJM Grantor Retained Annuity Trusts ranging from 11,963 to 40,935 shares. All transactions reported were made pursuant to a Rule 10b5-1 plan that Maetzold adopted on June 2, 2026, according to the filing.

What Was Disclosed

The Form 4 filed September 15, 2026 discloses that Castle Biosciences CEO Derek J. Maetzold exercised 8,584 stock options and sold shares directly and through multiple trusts on September 11, 2026, under a pre-established Rule 10b5-1 trading plan.