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DYN 424B5: Secondary offering

Dyne Therapeutics

Filed with the SEC on · accession 0001193125-26-310573

DYN filed a 424B5 (prospectus (offering)) with the SEC on Jul 21, 2026. Dyne Therapeutics filed a prospectus supplement for a $300 million common stock offering, with an underwriters' option for an additional $45 million. The stock moved +1.6% by the first close after the filing.

Summary of the filing

Dyne Therapeutics filed a prospectus supplement for a $300 million common stock offering, with an underwriters' option for an additional $45 million. The offering is being managed by Morgan Stanley, Jefferies, Evercore ISI, LifeSci Capital, and Raymond James.

For details, click here →How to read a 424B5 →

Key details

Total offering amount$300.0M
Over-allotment option$45.0M
IssuerDyne Therapeutics, Inc.
Joint book-running managerMorgan Stanley
Joint book-running managerJefferies
Joint book-running managerEvercore ISI
Joint book-running managerLifeSci Capital
Lead managerRaymond James

How DYN stock reacted

Close before

$23.45

Jul 20, 2026

First close after

+1.62%

$23.83

5 trading days

+9.30%

$25.63

Since filing

-25.97%

$17.36

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Frequently asked questions

What did DYN file with the SEC on Jul 21, 2026?

DYN filed a 424B5 (Secondary offering). Dyne Therapeutics filed a prospectus supplement for a $300 million common stock offering, with an underwriters' option for an additional $45 million. The offering is being managed by Morgan Stanley, Jefferies, Evercore ISI, LifeSci Capital, and Raymond James.

What does a secondary offering mean for DYN stock?

New shares dilute existing holders and are often sold at a discount to the market price.

How do I read a 424B5?

The final terms of an offering of shares or bonds. Look at price, number of shares and the discount to the market price. Large offerings dilute existing shareholders.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A 424B5 (prospectus (offering)): The final terms of an offering of shares or bonds.

How did DYN stock react to this filing?

DYN closed at $23.45 before the filing and $23.83 on Jul 21, 2026 (+1.62%). Five trading days later: $25.63 (+9.30%).

Other DYN SEC filings

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