MAETZOLD DEREK J 4

What Happened
Derek J. Maetzold, President, CEO and Director of Castle Biosciences (CSTL), exercised options on March 11, 2026 to acquire 6,226 shares at $2.39 each (cost ~$14,880). He then sold a total of roughly 44,125 shares in open-market transactions on March 11–12, 2026 for aggregate proceeds of approximately $1,132,820. The sales were reported as executed under a Rule 10b5-1 trading plan.

Key Details

• Dates and prices: option exercise on 2026-03-11 (6,226 shares @ $2.39); open-market sales on 2026-03-11 at a weighted avg $26.11 and on 2026-03-12 at a weighted avg $25.28. Reported trade-price ranges were about $24.90–$26.63 across the executions.
• Aggregate sales: ~44,125 shares sold for ~$1,132,820 in total.
• Options: the shares subject to the option were fully vested (footnote F13). The filing also shows a 6,226-share derivative conversion/disposition reported at $0 (reported separately).
• Plan/authorization: sales were made pursuant to a Rule 10b5-1 plan adopted by Maetzold on December 3, 2025 (footnote F1).
• Trust holdings: several holding notes indicate shares are held in family/grantor retained annuity trusts of which Maetzold is trustee or beneficiary (footnotes F3–F12).
• Filing/timeliness: Form 4 was filed March 13, 2026, reporting trades on March 11–12; this appears to be a timely filing under normal Form 4 deadlines.
• Shares owned after transaction: not specified in the provided transaction details.

Context

• This filing shows an option exercise followed by substantial open-market sales under a pre-established 10b5-1 plan. For retail investors, purchases (buys) often signal a stronger positive insider conviction than routine sales; sales executed under 10b5-1 plans are commonly pre-scheduled and may reflect routine liquidity or diversification rather than a change in view about the company.
• The derivative/zero-dollar disposition reported alongside the exercise can reflect net settlement mechanics (e.g., option conversion, withholding or transfer) — the filing lists it but does not provide extra detail on settlement mechanics.