Dyne Therapeutics (DYN) CEO John Cox Sells 5,658 Shares

What Happened John Cox, CEO, President and a director of Dyne Therapeutics (DYN), sold 5,658 shares in an open-market disposition on September 8, 2026, for a weighted average price of $18.88 per share, totaling approximately $106,823. The sale was executed to satisfy tax withholding obligations connected with the vesting of restricted stock units (RSUs) and was not a discretionary trade.

Key Details

• Transaction date: 2026-09-08. Transaction type: Sale (S); sale was to satisfy tax withholding tied to RSU vesting (see footnote F1).
• Price: weighted average $18.88; execution prices ranged $18.77–$18.92 (footnote F2).
• Shares sold: 5,658; proceeds ≈ $106,823.
• Ownership after transaction: the Form 4 notes 239,233 unvested RSUs (footnote F3). The filing does not provide a total beneficial ownership figure after this withholding sale.
• Additional note: some shares are held in a trust for the benefit of a child (footnote F4).
• Timeliness: Report filed and dated 2026-09-08 (no late filing indicated).

Context The sale was an automatic, contractual sale to cover tax withholding on vested RSUs (footnote F1). Such withholding sales are common and typically routine administrative actions rather than discretionary insider selling. The filing states the sale is consistent with a binding contract and the Rule 10b5-1 affirmative defense; it therefore should not be interpreted as a directional signal about Cox’s view of the company.