SEC Form 4 · accession 0001193125-26-281119

Dyne Therapeutics, Inc. · DYN

Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗

Table I — non-derivative securities

Table II — derivative securities

Explanation of responses

• F1This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by ForDyne B.V. ("ForDyne") on November 11, 2025.
• F2The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $20.13 to $20.97, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range(s) set forth in the footnotes of this Form 4.
• F3The shares are held directly by ForDyne. ForDyne is jointly owned by Forbion Capital Fund IV Cooperatief U.A. ("FCF IV") and Forbion Growth Opportunities Fund II Cooperatief U.A. ("FGO II"). Forbion IV Management B.V. ("Forbion Management") may be deemed to have voting and dispositive power over 2,421,886 of the shares of common stock held by ForDyne. Investment decisions with respect to the shares held by ForDyne can be made by FCPM III Services B.V., the director of Forbion Management, which may delegate such powers to its investment committee which may delegate such powers to the authorized representatives of Forbion Management. Messrs. Slootweg, van Osch, Mulder, van Houten, Reithinger and Boorsma (the "Partners") are partners of FCPM III Services B.V., which acts as the investment advisor to the directors of ForDyne. The Reporting Person is a partner of Forbion Management and a member of the investment committee of Forbion Management.
• F4(Continued from Footnote 2) Forbion Growth II Management B.V. ("FGO II Management"), the director of FGO II, may be deemed to have voting and dispositive power over 1,426,370 of the shares of common stock held by ForDyne. Investment decisions with respect to the shares held by ForDyne can be made by FCPM III Services B.V., the director of FGO II Management, which may delegate such powers to its investment committee which may delegate such powers to the authorized representatives of FGO II Management. The Partners are partners of FCPM III Services B.V., which acts as the investment advisor to the directors of ForDyne. The Reporting Person is a partner of FGO II Management and a member of the investment committee of FGO II Management. The Reporting Person disclaims beneficial ownership of the shares, except to the extent of his pecuniary interest therein.
• F5The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $20.45 to $21.44, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range(s) set forth in the footnotes of this Form 4.
• F6The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices within the range of $21.45 to $21.495, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range(s) set forth in the footnotes of this Form 4.