144 0001708269 XXXXXXXX LIVE 0001818794 Dyne Therapeutics, Inc. 001-39509 1560 Trapelo Road Waltham MA 02451 7817868230 Atlas Venture Fund XI, LP Shareholder Common Merrill Lynch 555 California Street 18th Floor San Francisco CA 94104 143749 2877854.98 165027119 04/21/2026 Nasdaq Common 07/31/2020 Private Placement Issuer N 143749 07/31/2020 Cash N Atlas Venture Fund XI, LP 300 Technology Sq 8th Floor Cambridge MA 02139 Common 04/20/2026 142571 2859490.52 Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139 Common 04/20/2026 71722 1438499.97 Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139 Common 04/20/2026 56355 1130290.09 Atlas Venture Associates XI, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139 Common 04/20/2026 1401 28099.31 04/21/2026 03/19/2026 Ommer Chohan