Castle Biosciences (CSTL) CEO Derek Maetzold Exercises Options, Sells Shares

What Happened

• Derek J. Maetzold, President & CEO and a director of Castle Biosciences (CSTL), exercised 12,428 stock options at $2.39 per share (cost $29,703) on 2026-08-28 and sold shares that same day. He sold 18,560 shares in open-market trades (multiple transactions) for gross proceeds of approximately $616,132. The filing also records a derivative disposal of 12,428 shares at $0 tied to the exercise event.
• These transactions were executed under a Rule 10b5-1 trading plan (adopted Dec 3, 2025). The option shares were fully vested per the filing.

Key Details

• Transaction date: August 28, 2026; Form 4 filed September 1, 2026 (timely within SEC rules).
• Exercise: 12,428 shares at $2.39; cost = $29,703.
• Open-market sales: 18,560 shares in multiple trades; reported weighted-average prices $33.14 and $33.88; gross proceeds ≈ $616,132.
• Net cash (sales proceeds minus exercise cost, before fees/taxes): ≈ $586,429.
• Notable footnotes: transactions pursuant to a 10b5-1 plan (F1); some sales were executed in multiple trades and reported as weighted-average prices with stated trade ranges (F2, F9); options fully vested (F14); several holdings recorded in family trusts (F3–F13).
• Shares owned after the transactions are not provided in the data you shared.

Context

• The filing shows an option exercise followed by same-day sales, a pattern often used as a cashless exercise or to provide liquidity to cover exercise/tax amounts. That pattern is common and factual — it does not by itself indicate the insider’s view on the company’s prospects.
• Sales (S) and exercise (M) codes: S = sale (open market), M = exercise/conversion of a derivative (option). Purchases are typically viewed as more informative for bullish signals; this filing primarily documents liquidity actions under a pre-established 10b5‑1 plan.