T. Rowe Price (NASDAQ: DYN) holds 30.8M shares, a 18.7% stake

Rhea-AI Filing Summary

T. Rowe Price Investment Management, Inc. amended its Schedule 13G to report beneficial ownership of 30,785,801 shares of Dyne Therapeutics common stock as of 03/31/2026. The filing shows sole voting power of 30,419,012 shares and a 18.7% ownership stake.

The filing is signed by Ellen York, Vice President, on 05/15/2026. The filer includes a statement denying beneficial ownership in the filing language.

Insights

Institutional Ownership Analyst

Large passive position reported: 30.8M shares (18.7%).

The filing records 30,785,801 shares beneficially owned with 30,419,012 shares of sole voting power as of 03/31/2026. This identifies a substantial institutional stake in the company.

Impact depends on whether holdings are passive or active; the filing’s statement denying beneficial ownership is a standard legal qualifier. Subsequent amendments or Schedule 13D filings would clarify intent.

Corporate Governance Specialist

Position size creates potential governance relevance but no corrective action shown.

A reported 18.7% stake can influence governance discussions; the document lists voting and dispositive powers explicitly. The signature date is 05/15/2026.

Whether this translates into board engagement or activism is not stated; later filings or public statements would show any change from passive ownership.

Key Figures

Shares beneficially owned: 30,785,801 shares Sole voting power: 30,419,012 shares Percent of class: 18.7% +1 more

4 metrics

Shares beneficially owned 30,785,801 shares as of 03/31/2026

Sole voting power 30,419,012 shares reported in ownership table

Percent of class 18.7% percent of common stock class

CUSIP 26818M108 Dyne Therapeutics common stock

Key Terms

Schedule 13G/A, beneficially owned, sole dispositive power

3 terms

Schedule 13G/A regulatory

"amendment language at top of excerpt"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficially owned financial

"Item 4. | Ownership (a) | Amount beneficially owned: 30785801"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

sole dispositive power regulatory

"Item 4. (iii) Sole power to dispose or to direct the disposition of: 30785801"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

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

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Accepted by SEC EDGAR 05/15/2026 - 10:06 AM Learn about SEC filing dates

FAQ

What stake did T. Rowe Price report in Dyne Therapeutics (DYN)?

T. Rowe Price reported beneficial ownership of 30,785,801 shares, equal to 18.7%. The filing states these figures are as of 03/31/2026 and shows sole voting power on 30,419,012 shares.

What voting and dispositive powers did the filing disclose?

The filing shows sole voting power for 30,419,012 shares and sole dispositive power for 30,785,801 shares. Shared voting and dispositive powers are reported as 0 in the provided excerpt.

When was the Schedule 13G/A signed and by whom?

The amendment was signed by Ellen York, Vice President, on 05/15/2026. The signature appears in the excerpt directly beneath the ownership table and affirmations.

Does the filing indicate T. Rowe Price is actively seeking control of DYN?

The filing does not state any activist intent; it includes a denial of beneficial ownership. The excerpt contains no statements about seeking control, and no Schedule 13D conversion or engagement is shown.

What CUSIP was reported for Dyne Therapeutics common stock?

The filing lists CUSIP 26818M108 for the common stock class. That CUSIP appears alongside the issuer name and class designation in the header of the excerpt.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

DYNE THERAPEUTICS INC

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

26818M108

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

T. Rowe Price Investment Management, Inc.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

MARYLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 30,419,012.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 30,785,801.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

30,785,801.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

18.7 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: DYNE THERAPEUTICS INC
(b)	Address of issuer's principal executive offices: 1560 TRAPELO ROAD, WALTHAM, MA, 02451
Item 2.
(a)	Name of person filing: T. Rowe Price Investment Management, Inc.
(b)	Address or principal business office or, if none, residence: 1307 Point Street, Baltimore, MD 21231
(c)	Citizenship: Maryland
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP No.: 26818M108
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 30785801
(b)	Percent of class: 18.7 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 30419012
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 30785801
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11. T. Rowe Price Investment Management, Inc. hereby declares and affirms that the filing of Schedule 13G shall not be construed as an admission that Price Investment Management is the beneficial owner of the securities referred to, which beneficial ownership is expressly denied.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

T. Rowe Price Investment Management, Inc.

Signature:	Ellen York
Name/Title:	Vice President
Date:	05/15/2026