Dyne Therapeutics, Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

Check the appropriate box:

Dyne Therapeutics, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

DYNE THERAPEUTICS, INC.

1560 Trapelo Road

Waltham, Massachusetts 02451

(781) 786-8230

NOTICE OF 2025 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on Friday, May 30, 2025

Dear Stockholder:

You are cordially invited to the 2025 Annual Meeting of Stockholders (the “2025 Annual Meeting”) of Dyne Therapeutics, Inc. The 2025 Annual Meeting will be held exclusively via the Internet in a virtual meeting format at www.proxydocs.com/DYN on Friday, May 30, 2025 at 11:00 a.m. Eastern Time. At the meeting, the stockholders will consider and vote on the following matters:

1. To elect two Class II directors, Edward Hurwitz and Dirk Kersten, each to serve for a three-year term expiring at the 2028 annual meeting of stockholders and until his respective successor has been duly elected and qualified;

2. To vote, on an advisory basis, to approve the compensation of our named executive officers;

3. To hold an advisory vote on the frequency of future advisory votes on the compensation of our named executive officers;

4. To ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025; and

5. To transact any other business that may properly come before the 2025 Annual Meeting or any adjournment or postponement thereof.

You may attend the 2025 Annual Meeting online atwww.proxydocs.com/DYN, where you will be able to vote your shares electronically during the meeting and submit questions during the meeting. Stockholders will not be able to attend the annual meeting in person. In order to attend the 2025 Annual Meeting online, you must register in advance at www.proxydocs.com/DYNprior to the commencement of the 2025 Annual Meeting. Upon completing your registration, you will receive further instructions via email, including a unique link that will allow you access to the 2025 Annual Meeting and to vote and submit questions during the 2025 Annual Meeting. Please follow the instructions found on your Notice Regarding the Availability of Proxy Materials, Proxy Card and/or Voting Instruction Card and subsequent instructions that will be delivered to you via email.

Stockholders of record at the close of business on April 4, 2025 will be entitled to notice of and to vote electronically during the 2025 Annual Meeting or any adjournment or postponement thereof. A list of registered stockholders as of the close of business on the record date will be available for examination by any stockholder for any purpose germane to the 2025 Annual Meeting during normal business hours at our principal executive offices at 1560 Trapelo Road, Waltham, Massachusetts 02451 during the 10-day period ending on the day before the 2025 Annual Meeting. We have elected to provide access to our proxy materials over the Internet under the Securities and Exchange Commission’s “notice and access” rules. We believe that providing our proxy materials over the Internet expedites stockholders’ receipt of proxy materials, lowers costs and reduces the environmental impact of our annual meeting.

We encourage all stockholders to attend the 2025 Annual Meeting online. However, whether or not you plan to attend the 2025 Annual Meeting, we encourage you to read the proxy statement and submit your proxy or voting instructions as soon as possible. Please review the instructions on each of your voting options described in the proxy statement.

By the Order of the Board of Directors,

/s/ John G. Cox

John G. Cox

President and Chief Executive Officer

Waltham, Massachusetts

April 15, 2025

Important Notice Regarding Internet Availability of Proxy Materials for the 2025 Annual Meeting of Stockholders to be Held on May 30, 2025: The proxy materials and our 2024 Annual Report to Stockholders, which includes our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, are available atwww.proxydocs.com/DYN. These documents are also available to any stockholder who wishes to receive a paper copy by calling 866-648-8133, visitingwww.investorelections.com/DYN or emailing paper@investorelections.com. Any requests for a paper copy of these documents should be received by May 17, 2025, in order to ensure timely delivery.

TABLE OF CONTENTS

DYNE THERAPEUTICS, INC.

1560 Trapelo Road

Waltham, Massachusetts 02451

(781) 786-8230