Certain Stock Options of Dyne Therapeutics, Inc. are subject to a Lock-Up Agreement Ending on 8-FEB-2026. These Stock Options will be under lockup for 61 days starting from 9-DEC-2025 to 8-FEB-2026.

Details:
The directors and officers, each of which we refer to as a ?lock-up party,? have agreed that, without the prior written consent of Morgan Stanley & Co. LLC and Jefferies LLC on behalf of the underwriters, they will not offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of common stock or any securities convertible into or exercisable or exchangeable for shares of common stock , and will cause any direct or indirect affiliate to not, during the restricted period (60 days after the date of this prospectus).