Cox John 4

What Happened
John Cox, CEO, President and a director of Dyne Therapeutics (DYN), disposed of 2,732 shares in an open-market sale on March 5, 2026 at $14.90 per share, for total proceeds of $40,707. According to the filing, the sale was an automatic transaction to satisfy tax withholding obligations tied to the vesting of restricted stock units (RSUs) and was not a discretionary trade.

Key Details

• Transaction date and price: 2026-03-05 — 2,732 shares @ $14.90 each. Total value: $40,707.
• Filing/Report dates: Period of Report 2026-03-05; Form 4 filed 2026-03-06.
• Transaction code: Sale (S); sale executed to satisfy tax withholding as described in footnote (see below).
• Shares owned after transaction: Not specified in the provided data. Filing notes include 279,895 unvested RSUs (F2).
• Footnotes: F1 — sale was automatic to satisfy tax withholding on RSU vesting (RSU grant dated Dec 4, 2024) and is provided for in the RSU agreement as a binding contract consistent with the affirmative defense under Rule 10b5-1; F3 — some shares are held in a trust for the benefit of a child.
• Timeliness: No late filing indicator shown in the provided data.

Context
The sale was executed to cover tax obligations from RSU vesting (a common, non-discretionary mechanism) and is disclosed as such in the filing. Such withholding sales are routine and generally viewed differently from voluntary insider sell decisions; they do not, by themselves, imply a change in the insider’s view of the company.