Dyne Therapeutics CEO John Cox Sells 4,986 Shares

What Happened

• John Cox, CEO, President and a director of Dyne Therapeutics (DYN), disposed of 4,986 shares in an open-market/private sale on August 13, 2026 for a weighted-average price of $26.28 per share, yielding about $131,032 in proceeds. This sale was to satisfy tax withholding tied to the vesting of restricted stock units (RSUs) granted Feb 12, 2026 and was executed under the RSU agreement (not a discretionary trade).

Key Details

• Transaction date: 2026-08-13; filing date (Form 4): 2026-08-17 (marked late).
• Shares sold: 4,986; weighted-average price: $26.28; price range across trades: $26.17–$26.39.
• Proceeds: ~$131,032.
• Holdings after transaction: reporting notes 248,314 unvested RSUs remain; some shares are held in a trust for the benefit of the reporting person’s child (no separate sale reported).
• Notable footnotes: sale was automatic to satisfy tax withholding in connection with RSU vesting and is provided for in a binding RSU agreement consistent with an affirmative defense under Rule 10b5-1; the filer can provide a per-trade price breakdown on request.
• Timeliness: filing was submitted 4 days after the transaction date and is marked late.

Context

• This was a tax-withholding sale tied to RSU vesting (routine) rather than an independent open-market sell decision; such transactions are common following vesting and do not necessarily signal management’s view of the company. Purchases by insiders tend to be more informative about positive sentiment than routine withholding sales.