Form 4: Castle Biosciences CEO Reports Routine Stock Transactions

Castle Biosciences' President and CEO, Derek J. Maetzold, reported routine transactions involving common stock and Restricted Stock Units, including tax withholdings and RSU conversions.

Summary

• Derek J. Maetzold, President & CEO and Director of Castle Biosciences, Inc. (CSTL), reported changes in his beneficial ownership.
• On March 3, 2026, 19,043 shares of common stock were disposed of at $27.57 per share to satisfy tax withholding obligations related to vested performance stock units.
• On March 4, 2026, 59,097 shares of common stock were acquired through the conversion/exercise of derivative securities (Restricted Stock Units).
• On March 4, 2026, an additional 17,931 shares of common stock were disposed of at $28.17 per share for tax withholding purposes.
• Following these transactions, Mr. Maetzold directly owns 105,821 shares of common stock.
• He also holds significant indirect beneficial ownership through various trusts, including The Maetzold Descendants 2020 Trust (52,923 shares), Derek Maetzold 2020 Irrevocable Trust (44,986 shares), and several other trusts.
• New grants of Restricted Stock Units (RSUs) were reported: 102,597 RSUs on March 3, 2026, which will vest in four equal annual installments starting March 3, 2027.
• Additionally, 31,110 RSUs from a March 4, 2024 grant and 27,987 RSUs from a March 4, 2025 grant were converted into common stock on March 4, 2026.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this as a neutral filing, reporting routine insider transactions related to executive compensation, including RSU vesting, conversion, and tax withholdings, which are standard practice and do not indicate any material change in company performance or outlook.

Positives

• Grant of 102,597 Restricted Stock Units (RSUs) to the CEO, indicating continued long-term incentive compensation.
• Conversion of 59,097 RSUs into common stock, reflecting the vesting and exercise of previously granted equity awards.

Negatives

• Disposal of 19,043 shares at $27.57 and 17,931 shares at $28.17 for tax withholding purposes, which reduces direct beneficial ownership.

Future Outlook

The filing indicates future vesting schedules for Restricted Stock Units, with 102,597 RSUs granted on March 3, 2026, set to vest in four equal annual installments beginning March 3, 2027. Additionally, previously granted RSUs from March 4, 2024, and March 4, 2025, continue their vesting schedules.

Industry Context

StockSavvy.ai notes that these transactions are typical for executive compensation, involving the vesting and conversion of Restricted Stock Units (RSUs) into common stock, followed by tax withholdings. This is a standard mechanism for aligning executive incentives with shareholder value over the long term, common across the biotechnology and diagnostics industry where Castle Biosciences operates.

Comparison to Industry Standards

• StockSavvy.ai observes that the structure of equity compensation, including RSU grants and subsequent tax withholdings upon vesting, aligns with common practices seen in comparable publicly traded biotechnology and diagnostics companies.
• For instance, companies like Guardant Health (GH) or Exact Sciences (EXAS) frequently utilize similar equity incentive plans for their executives, where a portion of vested shares is routinely sold to cover tax liabilities.
• The reported RSU grants and conversions are consistent with standard executive compensation packages designed to retain talent and incentivize performance over multi-year periods.

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 Trust FBO Emily Carol Kirk, where the reporting person is trustee and his child is the beneficiary.
• Indirect beneficial ownership through The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold, where the reporting person is trustee and his child is the beneficiary.
• Indirect beneficial ownership through The Maetzold 2018 Remainder Trust FBO John Derek Maetzold, where the reporting person is trustee and his child is the beneficiary.
• Indirect beneficial ownership through The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold, where the reporting person is trustee and his child is the beneficiary.
• Indirect beneficial ownership through DJM Grantor Retained Annuity Trust No. 5, 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 other Maetzold 2018 Remainder Trusts.
• Indirect beneficial ownership through DJM Grantor Retained Annuity Trust No. 7, where the reporting person is trustee and beneficiary.

Stakeholder Impact

• Shareholders: Reflects routine changes in executive ownership and compensation structure, which is a standard aspect of corporate governance.
• Employees: No direct impact on the broader employee base is indicated, but it highlights the company's executive compensation practices.
• Management: The transactions are part of the CEO's ongoing compensation and equity holdings, aligning his interests with long-term company performance.

Next Steps

• Vesting of 102,597 RSUs in four equal annual installments beginning March 3, 2027.
• Continued vesting of RSUs granted on March 4, 2024, and March 4, 2025.

Key Dates

Keywords

Castle Biosciences, CSTL, Form 4, insider transaction, beneficial ownership, Restricted Stock Units, RSU, common stock, executive compensation, tax withholding