DYN affiliate lists 3,311-share sale; 9,081 RSUs noted

DYN affiliate filings report proposed and recent transactions in Common Stock.

Rhea-AI Filing Summary

DYN affiliate filings report proposed and recent transactions in Common Stock. The excerpt shows 3,311 shares sold on 05/13/2026 by John Cox and a planned disposition of 9,081 Restricted Stock Units dated 06/04/2026 described as Equity Compensation. The broker listed is Stifel Nicolaus & Company Inc. Shares outstanding are shown as 165,313,769 as of 06/16/2026.

Insights

Securities Counsel

Form 144-style notice of proposed resale and recent sale by an affiliate.

Records list a 05/13/2026 sale of 3,311 shares by John Cox and a 06/04/2026 entry for 9,081 Restricted Stock Units identified as equity compensation. The broker shown is Stifel Nicolaus & Company Inc.

These entries reflect resales and compensation-related dispositions; timing and final cash‑flow treatment are not provided in the excerpt and will depend on settlement and any resale mechanics.

Key Figures

Shares sold (John Cox): 3,311 shares Restricted Stock Units: 9,081 units Shares outstanding: 165,313,769 shares +1 more

4 metrics

Shares sold (John Cox) 3,311 shares sale dated 05/13/2026

Restricted Stock Units 9,081 units entry dated 06/04/2026 labeled Equity Compensation

Shares outstanding 165,313,769 shares as of 06/16/2026

Form type Form 144 notification of proposed resale by an affiliate

Key Terms

Restricted Stock Units, Equity Compensation, Form 144, Brokerage (Stifel Nicolaus)

4 terms

Restricted Stock Units financial

"Restricted Stock Units | 06/04/2026 | Issuer | 9,081"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

Equity Compensation financial

"06/04/2026 | Restricted Stock Units | Issuer | Equity Compensation"

Equity compensation is pay given to employees, executives or contractors in the form of company ownership—such as stock, stock options or restricted shares—rather than just cash. It matters to investors because it can align workers' incentives with shareholders (like paying someone in slices of the same pie they help grow), but it also increases the number of shares outstanding and company expenses, affecting ownership percentages and earnings per share.

Form 144 regulatory

"CONTENT METADATA: "form_type": "144""

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.

Brokerage (Stifel Nicolaus) financial

"Stifel Nicolaus & Company Inc 501 N Broadway St. Louis MO 63102"

FAQ

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

What does the DYN Form 144 excerpt show about recent transactions?

The excerpt shows a sale of 3,311 shares on 05/13/2026 by John Cox and an entry for 9,081 Restricted Stock Units dated 06/04/2026 classified as equity compensation.

Who is the broker handling the resale entries in the DYN filing?

The filing lists Stifel Nicolaus & Company Inc. at 501 N Broadway, St. Louis, MO, as the broker shown in the securities information section of the excerpt.

How many DYN shares outstanding are shown in the excerpt?

The excerpt lists 165,313,769 shares outstanding with an associated date of 06/16/2026 in the securities information lines.

Are the 9,081 Restricted Stock Units in the excerpt already sold?

The excerpt lists 9,081 Restricted Stock Units with a date of 06/04/2026 under Restricted Stock Units and Equity Compensation, indicating a reported disposition entry rather than a confirmed cash settlement.

Does the excerpt disclose the cash proceeds or prices for the transactions?

The provided excerpt does not state aggregate proceeds or per‑share sale prices for the listed transactions; the lines show share counts and dates but no explicit price or proceeds information.

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

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Accepted by SEC EDGAR 06/16/2026 - 04:10 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	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	2683	49191.00	165313769	06/16/2026	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	06/04/2026	Restricted Stock Units	Issuer			9081	06/16/2026	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	05/13/2026	3311	60805.00

144: Remarks and Signature

Remarks
Date of Notice	06/16/2026
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/ James Weimer, 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)