GlobeNewswire Inc | Sep 21, 2020 04:05PM EDT

September 21, 2020

WALTHAM, Mass., Sept. 21, 2020 (GLOBE NEWSWIRE) -- Dyne Therapeutics, Inc. (Nasdaq: DYN), a muscle disease company focused on advancing innovative life-transforming therapeutics for patients with genetically driven diseases, today announced the closing of its initial public offering of 14,089,314 shares of its common stock at an initial public offering price of$19.00per share, including 1,837,736 additional shares of common stock issued upon the exercise in full by the underwriters of their option to purchase additional shares. All of the shares in the offering were sold byDyne. The gross proceeds of the offering, before deducting the underwriting discount and commissions and other offering expenses payable byDyne, were approximately$268 million.

The shares began trading on the Nasdaq Global Select Market onThursday, September 17, 2020under the ticker symbol DYN.

J.P. Morgan, Jefferies, Piper Sandler and Stifel acted as joint book-running managers for the offering.

A registration statement relating to the securities sold in this offering was filed with, and declared effective by, theSecurities and Exchange Commission (the SEC). Copies of the registration statement can be accessed through the SECs website atwww.sec.gov. This offering was made only by means of a prospectus. Copies of the final prospectus relating to this offering may be obtained fromJ.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, via telephone at (866) 803-9204 or via email at prospectus-eq_fi@jpmchase.com; Jefferies LLC, Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 2nd Floor, New York, New York 10022, via telephone at (877) 821-7388 or via email at Prospectus_Department@Jefferies.com; Piper Sandler & Co., Attention: Prospectus Department, 800 Nicollet Mall, J12S03, Minneapolis, Minnesota 55402, via telephone at (800) 747-3924 or via email at prospectus@psc.com; or Stifel, Nicolaus & Company, Incorporated, Attention: Syndicate, One Montgomery Street, Suite 3700, San Francisco, California 94104, via telephone at (415) 364-2720 or via email at syndprospectus@stifel.com.

This press release shall not constitute an offer to sell, or a solicitation of an offer to buy these securities, nor shall there be any offer or sale of, these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or jurisdiction.

About Dyne Therapeutics

Dyne Therapeutics is building a leading muscle disease company focused on advancing innovative life-transforming therapeutics for patients with genetically driven diseases. The Company utilizes its proprietary FORCE platform to overcome the current limitations of muscle tissue delivery with modern oligonucleotide therapeutic candidates. Dyne is developing a broad portfolio of therapeutics for muscle diseases, including lead programs in myotonic dystrophy type 1 (DM1), Duchenne muscular dystrophy (DMD) and facioscapulohumeral muscular dystrophy (FSHD).

Contacts:

Dyne TherapeuticsAmy Reillyareilly@dyne-tx.com857-341-1203

Media

Ten Bridge CommunicationsStephanie Simon stephanie@tenbridgecommunications.com617-581-9333