DYN Form 144: Atlas Venture plans resale of shares

DYN notice reports proposed resale of Common Stock by several Atlas Venture funds.

Rhea-AI Filing Summary

DYN notice reports proposed resale of Common Stock by several Atlas Venture funds. The excerpt lists four selling entities proposing sales on 04/20/2026 with specified share amounts and gross proceeds. The transactions are identified as sales of restricted securities from a prior Private Placement.

Insights

Capital Markets Analyst

Form 144 shows institutional holders proposing to resell shares obtained in a private placement.

The filing lists specific selling entities and exact share amounts with reported gross proceeds: Atlas Venture Fund XI, LP (142,571 shares, $2,859,490.52), Atlas Venture Opportunity Fund II, L.P. (71,722 shares, $1,438,499.97), Atlas Venture Opportunity Fund I, L.P. (56,355 shares, $1,130,290.09), and Atlas Venture Associates XI, L.P. (1,401 shares, $28,099.31), all dated 04/20/2026.

The primary dependency is whether these sales occur and market reception; cash‑flow treatment to the issuer is not stated. Subsequent SEC filings or broker reports will show whether the sales were completed.

Securities Compliance Specialist

These Form 144 entries are routine resale notices tied to a prior private placement.

Form 144 provides the statutory notice required for resale of restricted/controlled stock; it records who plans to sell and the amounts. The excerpt references a Private Placement dated 12/12/2022, indicating original acquisition method.

Timing and execution methods are not included; completion and any Rule 144 limitations depend on market transactions and broker confirmations.

Key Figures

Atlas Venture Fund XI proposed sale: 142,571 shares Atlas Venture Fund XI gross proceeds: $2,859,490.52 Atlas Venture Opportunity Fund II proposed sale: 71,722 shares +5 more

8 metrics

Atlas Venture Fund XI proposed sale 142,571 shares proposed sale on <date>04/20/2026</date>

Atlas Venture Fund XI gross proceeds $2,859,490.52 reported for 142,571 shares

Atlas Venture Opportunity Fund II proposed sale 71,722 shares proposed sale on <date>04/20/2026</date>

Atlas Venture Opportunity Fund II gross proceeds $1,438,499.97 reported for 71,722 shares

Atlas Venture Opportunity Fund I proposed sale 56,355 shares proposed sale on <date>04/20/2026</date>

Atlas Venture Opportunity Fund I gross proceeds $1,130,290.09 reported for 56,355 shares

Atlas Venture Associates XI proposed sale 1,401 shares proposed sale on <date>04/20/2026</date>

Atlas Venture Associates XI gross proceeds $28,099.31 reported for 1,401 shares

Key Terms

Form 144, Private Placement, Gross proceeds

3 terms

Form 144 regulatory

"Securities To Be Sold / Securities Sold During The Past 3 Months"

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

"Common | 12/12/2022 | Private Placement"

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.

Gross proceeds financial

"Atlas Venture Fund XI, LP ... 142571 | 2859490.52"

The total amount of cash a company receives from a financing event or sale before any fees, expenses, taxes or deductions are taken out. Investors watch gross proceeds because it shows the raw scale of new capital being raised—think of it as the paycheck amount before withholdings—which helps assess how much funding is available for operations, growth, debt payoff or how much shareholder dilution might occur once costs are removed.

FAQ

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

What does DYN's Form 144 filing mean for shareholders?

It notifies the SEC of proposed resale by holders; Atlas funds listed plan to offer shares on 04/20/2026. The filing lists exact share counts and gross proceeds but does not confirm completed sales or market timing.

Which entities are listed as selling DYN shares in this Form 144?

The selling holders are Atlas Venture Fund XI, LP; Atlas Venture Opportunity Fund II, L.P.; Atlas Venture Opportunity Fund I, L.P.; and Atlas Venture Associates XI, L.P. Each entry shows shares and gross proceeds dated 04/20/2026.

How many DYN shares did Atlas Venture Fund XI, LP propose to sell?

Atlas Venture Fund XI, LP proposed to sell 142,571 shares, with reported gross proceeds of $2,859,490.52. The filing lists the proposed sale date as 04/20/2026.

Does the Form 144 indicate whether DYN receives proceeds from these sales?

No. The excerpt shows these are resales by holders from a prior Private Placement; it does not state that the issuer will receive any proceeds or describe use of proceeds.

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	0001885327
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 Opportunity Fund II, 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	72315	1447746.3	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	12/12/2022	Private Placement	Issuer			72315	12/12/2022	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)