Dyne Therapeutics (DYN) CMO Kerr Douglas Sells Shares

What Happened
Kerr Douglas, Chief Medical Officer of Dyne Therapeutics (DYN), reported two sales totaling 5,035 shares for aggregate proceeds of about $115,546. On 2026-09-04 he sold 3,745 shares at a weighted-average price of $24.35 (range $24.27–$24.50) for approximately $91,191. On 2026-09-08 he sold 1,290 shares at a weighted-average price of $18.88 (range $18.77–$18.92) for approximately $24,355. Both sales were automatic disposals to satisfy tax withholding obligations arising from RSU vestings.

Key Details

• Transaction dates and prices:
  • 2026-09-04: 3,745 shares sold @ weighted avg $24.35 (prices $24.27–$24.50) — ~$91,191 (F2)
  • 2026-09-08: 1,290 shares sold @ weighted avg $18.88 (prices $18.77–$18.92) — ~$24,355 (F4)
• Total: 5,035 shares sold for ≈ $115,546.
• Nature of sales: Automatic tax-withholding sales tied to RSU vesting (grants dated 2024-09-03 and 2024-12-04). These are non‑discretionary per the RSU agreements and consistent with the Rule 10b5-1 affirmative defense (F1, F3).
• Holdings after transaction: Reported holdings include 125,126 unvested RSUs (F5). The filing does not provide a separate total of fully owned shares.
• Filing: Form 4 filed 2026-09-08 (covers transactions on 2026-09-04 and 2026-09-08). The footnotes note the weighted-average price ranges; the reporting person will provide breakdowns on request.

Context
These sales were routine, administrative dispositions to cover tax withholding on vested restricted stock units, not discretionary open‑market trades. Such withholding sales are common following RSU vesting and do not necessarily signal management sentiment about the company. Purchases by insiders are generally more informative as potential bullish signals; these RSU-withholding sales are primarily compensatory/tax-driven.