DYN files Rule 144 notice for 9,081 RSUs

DYN submitted a Rule 144 notice reporting planned transactions in its common stock.

Accepted by SEC EDGAR 03/05/2026 - 04:06 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

DYN submitted a Rule 144 notice reporting planned transactions in its common stock. The filing lists 9,081 Restricted Stock Units described as "Equity Compensation" with a 03/04/2026 date and identifies Stifel Nicolaus & Company Inc as the broker. The filing also records a prior sale by John Cox of 2,662 common shares on 12/05/2025 for $55,150.00.

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Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001498428
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Dyne Therapeutics, Inc.
SEC File Number	001-39509
Address of Issuer	1560 TRAPELO ROAD WALTHAM MASSACHUSETTS 02451
Phone	(781) 786-8230
Name of Person for Whose Account the Securities are To Be Sold	Cox John
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Stifel Nicolaus & Company Inc 501 N Broadway St. Louis MO 63102	2732	40707.00	164650000	03/05/2026	Nasdaq

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common Stock	03/04/2026	Restricted Stock Units	Issuer			9081	03/04/2026	Equity Compensation

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
John Cox 1560 Trapelo Rd Waltham MA 02451	Common Stock	12/05/2025	2662	55150.00

144: Remarks and Signature

Remarks
Date of Notice	03/05/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Luca Lotito, as a duly authorized representative of STIFEL, as attorney-in-fact for John Cox
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)