DYN files Form 144 reporting affiliate stock sales

DYN filed a Form 144 reporting proposed affiliate sales of Common Stock and disclosing recent dispositions.

Rhea-AI Filing Summary

DYN filed a Form 144 reporting proposed affiliate sales of Common Stock and disclosing recent dispositions.

The filing references securities issued in a Private Placement dated 04/26/2019 and lists recent sales on 04/20/2026 by Atlas Venture entities, including Atlas Venture Fund XI, LP: 142,571 shares for $2,859,490.52 and Atlas Venture Opportunity Fund II, L.P.: 71,722 shares for $1,438,499.97.

Insights

Securities Counsel

Form 144 discloses affiliate share dispositions and prior private placement origin.

The filing lists proposed sales of Common Stock tied to a Private Placement dated 04/26/2019 and reports multiple dispositions on 04/20/2026 by Atlas Venture entities. Cash consideration amounts are shown per holder in the excerpt.

Cash‑flow treatment to the issuer is not stated in the excerpt; subsequent filings or transaction confirmations may clarify whether proceeds went to selling holders or the company.

Key Figures

Disposition date: 04/20/2026 Atlas Venture Fund XI, LP shares: 142,571 shares Atlas Venture Fund XI, LP proceeds: $2,859,490.52 +3 more

6 metrics

Disposition date 04/20/2026 date of listed sales by Atlas Venture entities

Atlas Venture Fund XI, LP shares 142,571 shares shares sold on 04/20/2026

Atlas Venture Fund XI, LP proceeds $2,859,490.52 cash amount shown for 142,571 shares

Atlas Venture Opportunity Fund II shares 71,722 shares shares sold on 04/20/2026

Atlas Venture Opportunity Fund II proceeds $1,438,499.97 cash amount shown for 71,722 shares

Private Placement date 04/26/2019 origin date for the securities referenced

Key Terms

Form 144, Private Placement, Broker‑dealer

3 terms

Form 144 regulatory

"reported proposed affiliate sales of Common Stock and disclosing recent dispositions"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Private Placement financial

"references securities issued in a Private Placement dated 04/26/2019"

A private placement is a sale of securities directly to a selected group of investors, typically institutions or accredited investors, instead of through a public offering. It lets a company raise money faster and with fewer regulatory steps; for existing shareholders it matters because the newly issued shares, often sold at a discount, increase the share count and can dilute their ownership.

Broker‑dealer market

"Common | Merrill Lynch 555 California Street 18th Floor San Francisco CA 94104"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does DYN's Form 144 reveal about recent insider or affiliate sales?

It reports affiliate dispositions of Common Stock on 04/20/2026, listing sellers and amounts. The excerpt names Atlas Venture entities and shows share counts and cash amounts for each disposition, such as 142,571 shares for $2,859,490.52.

Which Atlas Venture entities sold DYN shares and how many?

The excerpt lists multiple Atlas Venture affiliates selling Common Stock on 04/20/2026. Examples include Atlas Venture Fund XI, LP (142,571 shares) and Atlas Venture Opportunity Fund II, L.P. (71,722 shares).

Was the stock sold originally issued in a private placement for DYN?

Yes, the filing references a Private Placement dated 04/26/2019. The excerpt ties the securities to that issuance date but does not further detail original terms in the provided text.

What cash amounts are shown for the disclosed DYN share sales?

The excerpt shows cash proceeds by seller, for example $2,859,490.52 for 142,571 shares and $1,438,499.97 for 71,722 shares. Those figures appear in the selling‑holder rows of the excerpt.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 04/21/2026 - 04:53 PM EDT Learn about SEC filing dates

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	0001780068
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	7817868230
Name of Person for Whose Account the Securities are To Be Sold	Atlas Venture Associates XI, LP
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	Shareholder

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	Merrill Lynch 555 California Street 18th Floor San Francisco CA 94104	1413	28288.26	165027119	04/21/2026	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	04/26/2019	Private Placement	Issuer			1413	04/26/2019	Cash

* 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
Atlas Venture Fund XI, LP 300 Technology Sq 8th Floor Cambridge MA 02139	Common	04/20/2026	142571	2859490.52
Atlas Venture Opportunity Fund II, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139	Common	04/20/2026	71722	1438499.97
Atlas Venture Opportunity Fund I, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139	Common	04/20/2026	56355	1130290.09
Atlas Venture Associates XI, L.P. 300 Technology Sq 8th Floor Cambridge MA 02139	Common	04/20/2026	1401	28099.31

144: Remarks and Signature

Remarks
Date of Notice	04/21/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/19/2026
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	Ommer Chohan
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)