Castle Biosciences CEO Derek Maetzold's Stock Transactions Under 10b5-1 Plan

This Form 4 filing reports that Derek J. Maetzold, President and CEO of Castle Biosciences Inc., executed multiple stock transactions on July 14, 2026, pursuant to a Rule 10b5-1 trading plan adopted on December 3, 2025. The transactions include the exercise of stock options for 550 shares at $2.39 per share and the sale of 550 personally held shares at a weighted average price of $22.92. Additionally, Maetzold sold shares held indirectly through various family trusts totaling 3,624 shares at the same $22.92 price. Following these transactions, Maetzold directly holds 21,479 shares and maintains significant indirect holdings through multiple grantor retained annuity trusts and family trusts. All transactions were executed under the pre-established 10b5-1 plan, which provides an affirmative defense against insider trading allegations.