Dyne Therapeutics (DYN): Atlas Venture funds report 3.6% beneficial stake in 13G/A

Rhea-AI Filing Summary

Dyne Therapeutics, Inc. common stock is reported as beneficially owned by several affiliated Atlas Venture funds and associated entities in this amended Schedule 13G. Atlas Venture Fund XI and its related entities report beneficial ownership of 4,479,449 shares, the Opportunity Fund I entities report 975,931 shares, and the Opportunity Fund II entities report 1,344,719 shares of common stock. Based on 186,746,431 shares outstanding as of July 24, 2026, the filing states that the Fund XI entities each may be deemed to own 2.4% of the class, the Opportunity Fund entities 0.5%, and the Opportunity Fund II entities 0.7%. Collectively, the reporting persons may be deemed to beneficially own 6,800,099 shares, or 3.6% of the company’s outstanding common stock, while each reporting group indicates ownership of 5% or less of the class.

Key Figures

Fund XI shares: 4,476,487 shares Fund XI total beneficial: 4,479,449 shares Opportunity Fund I shares: 975,931 shares +5 more

8 metrics

Fund XI shares 4,476,487 shares Shares of Dyne Therapeutics common stock held of record by Atlas Venture Fund XI, L.P.

Fund XI total beneficial 4,479,449 shares Shares over which Fund XI reporting persons have shared voting and dispositive power

Opportunity Fund I shares 975,931 shares Shares held of record by Atlas Venture Opportunity Fund I, L.P.

Opportunity Fund II shares 1,344,719 shares Shares held of record by Atlas Venture Opportunity Fund II, L.P.

Total beneficial ownership 6,800,099 shares Aggregate shares Dyne Therapeutics common stock beneficially owned by all reporting persons

Ownership percentage total 3.6% Aggregate percentage of Dyne Therapeutics outstanding common stock beneficially owned

Shares outstanding 186,746,431 shares Dyne Therapeutics common shares outstanding as of July 24, 2026

Fund XI percentage 2.4% Percentage of Dyne Therapeutics common stock for each Fund XI reporting person

Key Terms

beneficially own, shared voting power, shared dispositive power, Schedule 13G, +1 more

5 terms

beneficially own regulatory

"Each of Atlas XI, AVA XI LP and AVA XI LLC may be deemed to beneficially own the shares"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

shared voting power regulatory

"Each of AVA XI LP and AVA XI LLC shares power to vote or direct the vote of 4,479,449"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power regulatory

"shares power to dispose or to direct the disposition of 4,476,487 shares of Common Stock"

Schedule 13G regulatory

"Collectively, the Reporting Persons beneficially own an aggregate of 6,800,099 shares"

A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.

CUSIP No. financial

"Title of class of securities: COMMON STOCK, $0.0001 PAR VALUE (e) | CUSIP No.: 26818M108"

FAQ

What ownership in Dyne Therapeutics (DYN) do the Atlas Venture entities report?

The Atlas Venture entities report beneficial ownership of 6,800,099 shares of Dyne Therapeutics common stock, representing 3.6% of the company’s outstanding shares based on 186,746,431 shares outstanding as of July 24, 2026.

How much of Dyne Therapeutics (DYN) does Atlas Venture Fund XI specifically hold?

Atlas Venture Fund XI is the record owner of 4,476,487 shares of Dyne Therapeutics common stock. Related entity AVA XI L.P. directly holds an additional 2,962 shares, over which Atlas XI-related entities have shared voting and dispositive power and may be deemed to beneficially own.

What percentage of Dyne Therapeutics (DYN) is owned by each Atlas Venture reporting group?

The filing states the Fund XI reporting persons each may be deemed to beneficially own 2.4% of Dyne Therapeutics common stock, the Opportunity Fund reporting persons 0.5%, and the Opportunity Fund II reporting persons 0.7% of the outstanding common stock.

What is the Dyne Therapeutics (DYN) share count used for the ownership percentages?

Ownership percentages are calculated using 186,746,431 Dyne Therapeutics common shares outstanding as of July 24, 2026, as reported in the company’s Form 10-Q filed on July 29, 2026, which serves as the baseline for the 13G ownership calculations.

Do the Atlas Venture reporting persons claim to be a group in Dyne Therapeutics (DYN)?

The filing notes the reporting persons are under common control and may be deemed a group, but they expressly disclaim group membership. It states this should not be deemed an admission that they form a group for Section 13 or other purposes.

Do any Atlas Venture entities report sole voting or dispositive power over Dyne Therapeutics (DYN) shares?

No reporting person claims sole voting or sole dispositive power over Dyne Therapeutics shares. All reported voting and dispositive powers are shared among the relevant Atlas Venture funds and their associated general partner entities.

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

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Available on EDGAR 08/13/2026 - 04:51 PM Accepted by SEC EDGAR 08/13/2026 - 04:51 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 6)

DYNE THERAPEUTICS, INC.

(Name of Issuer)

COMMON STOCK, $0.0001 PAR VALUE

(Title of Class of Securities)

26818M108

(CUSIP Number)

06/30/2026

(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

Atlas Venture Fund XI, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,476,487.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,476,487.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,476,487.00

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)

2.4 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates XI, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,479,449.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,479,449.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,479,449.00

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)

2.4 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates XI, LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 4,479,449.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,479,449.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,479,449.00

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)

2.4 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Opportunity Fund I, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 975,931.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 975,931.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

975,931.00

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)

0.5 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates Opportunity I, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 975,931.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 975,931.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

975,931.00

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)

0.5 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates Opportunity I, LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 975,931.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 975,931.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

975,931.00

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)

0.5 %

12

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Opportunity Fund II, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,344,719.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,344,719.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,344,719.00

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)

0.7 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates Opportunity II, L.P.

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,344,719.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,344,719.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,344,719.00

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)

0.7 %

12

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13G

CUSIP Number(s): 26818M108

1

Names of Reporting Persons

Atlas Venture Associates Opportunity II, LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,344,719.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,344,719.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,344,719.00

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)

0.7 %

12

Type of Reporting Person (See Instructions)

OO

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: This Schedule 13G is filed by (i) Atlas Venture Fund XI, L.P., a Delaware limited partnership ("Atlas XI"), (ii) Atlas Venture Associates XI, L.P., a Delaware limited partnership ("AVA XI LP"), (iii) Atlas Venture Associates XI, LLC, a Delaware limited liability company ("AVA XI LLC" and together with Atlas XI and AVA XI LP, the "Fund XI Reporting Persons"), (iv) Atlas Venture Opportunity Fund I, L.P., a Delaware limited partnership ("AVO I"), (v) Atlas Venture Associates Opportunity I, L.P., a Delaware limited partnership ("AVAO LP"), (vi) Atlas Venture Associates Opportunity I, LLC, a Delaware limited liability company ("AVAO LLC" and together with AVO I and AVAO LP, the "Opportunity Fund Reporting Persons"), (vii) Atlas Venture Opportunity Fund II, L.P., a Delaware limited partnership ("AVO II"), (viii) Atlas Venture Associates Opportunity II, L.P., a Delaware limited partnership ("AVAO II LP") and (ix) Atlas Venture Associates Opportunity II, LLC, a Delaware limited liability company ("AVAO II LLC" and together with AVO II and AVAO II LP, the "Opportunity Fund II Reporting Persons" and together with the Fund XI Reporting Persons and Opportunity Fund Reporting Persons, the "Reporting Persons").
(b)	Address or principal business office or, if none, residence: 300 Technology Square, 8th Floor Cambridge, Massachusetts 02139
(c)	Citizenship: Each of Atlas XI, AVA XI LP, AVO I, AVAO LP, AVO II and AVAO II LP is a Delaware limited partnership. Each of AVA XI LLC, AVAO LLC and AVAO II LLC is a Delaware limited liability company.
(d)	Title of class of securities: COMMON STOCK, $0.0001 PAR VALUE
(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: Atlas XI is the record owner of 4,476,487 shares of Common Stock. AVA XI LP is the general partner of Atlas XI and AVA XI LLC is the general partner of AVA XI LP. Each of Atlas XI, AVA XI LP and AVA XI LLC has shared voting and dispositive power over the shares held by Atlas XI. As such, each of Atlas XI, AVA XI LP and AVA XI LLC may be deemed to beneficially own the shares held by Atlas XI. AVA XI LP is the record owner of 2,962 shares of Common Stock. AVA XI LLC is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC has shared voting and dispositive power over the shares held by AVA XI LP. As such, each of AVA XI LP and AVA XI LLC may be deemed to beneficially own the shares held by AVA XI LP. AVO I is the record owner of 975,931 shares of Common Stock. AVAO LP is the general partner of AVO I and AVAO LLC is the general partner of AVAO LP. Each of AVO I, AVAO LP and AVAO LLC has shared voting and dispositive power over the shares held by AVO I. As such, each of AVO I, AVAO LP and AVAO LLC may be deemed to beneficially own the shares held by AVO I. AVO II is the record owner of 1,344,719 shares of Common Stock. AVAO II LP is the general partner of AVO II and AVAO II LLC is the general partner of AVAO II LP. Each of AVO II, AVAO II LP and AVAO II LLC has shared voting and dispositive power over the shares held by AVO II. As such, each of AVO II, AVAO II LP and AVAO II LLC may be deemed to beneficially own the shares held by AVO II.
(b)	Percent of class: Each of the Fund XI Reporting Persons may be deemed to beneficially own 2.4% of the Issuer's outstanding Common Stock. Each of the Opportunity Fund Reporting Persons may be deemed to beneficially own 0.5% of the Issuer's outstanding Common Stock. Each of the Opportunity Fund II Reporting Persons may be deemed to beneficially own 0.7%, of the Issuer's outstanding Common Stock. These percentages are calculated based upon 186,746,431 outstanding shares of Common Stock of the Issuer as of July 24, 2026, as reported in the Issuer's Form 10-Q, filed with the Securities and Exchange Commission on July 29, 2026. Collectively, the Reporting Persons beneficially own an aggregate of 6,800,099 shares of Common Stock, which represents 3.6% of the Issuer's outstanding Common Stock. The Fund XI Reporting Persons, Opportunity Fund Reporting Persons and Opportunity Fund II Reporting Persons are under common control and as a result, the Reporting Persons may be deemed to be members of a group. However, the Reporting Persons disclaim such group membership, and this Schedule 13G shall not be deemed an admission that the Reporting Persons are members of a group for purposes of Section 13 or for any other purposes.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: None of the Reporting Persons have the sole power to direct the vote of the Common Stock.
	(ii) Shared power to vote or to direct the vote: Atlas XI shares power to vote or direct the vote of 4,476,487 shares of Common Stock. Each of AVA XI LP and AVA XI LLC shares power to vote or direct the vote of 4,479,449 shares of Common Stock. Each Opportunity Fund Reporting Person shares power to vote or direct the vote of 975,931 shares of Common Stock. Each Opportunity Fund II Reporting Person shares power to vote or direct the vote of 1,344,719 shares of Common Stock.
	(iii) Sole power to dispose or to direct the disposition of: None of the Reporting Persons have the sole power to dispose or to direct the disposition of the Common Stock.
	(iv) Shared power to dispose or to direct the disposition of: Atlas XI shares power to dispose or to direct the disposition of 4,476,487 shares of Common Stock. Each of AVA XI LP and AVA XI LLC shares power to dispose or to direct the disposition of 4,479,449 shares of Common Stock. Each Opportunity Fund Reporting Person shares power to dispose or to direct the disposition of 975,931 shares of Common Stock. Each Opportunity Fund II Reporting Person shares power to dispose or to direct the disposition 1,344,719 shares of Common Stock.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
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:
	Not Applicable

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.

Atlas Venture Fund XI, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates XI, L.P., its general partner, By: Atlas Venture Associates XI, LLC, its general partner, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates XI, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates XI, LLC, its general partner, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates XI, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Opportunity Fund I, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity I L.P., its GP, By: Atlas Venture Associates Opportunity I LLC, its GP, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates Opportunity I, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity I LLC, its GP, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates Opportunity I, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Opportunity Fund II, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity II L.P., its GP, By: Atlas Venture Associates Opportunity II LLC, its GP, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates Opportunity II, L.P.

Signature:	/s/ Ommer Chohan
Name/Title:	By: Atlas Venture Associates Opportunity II LLC, its GP, By: Ommer Chohan, its CFO
Date:	08/13/2026

Atlas Venture Associates Opportunity II, LLC

Signature:	/s/ Ommer Chohan
Name/Title:	Ommer Chohan, its CFO
Date:	08/13/2026

Exhibit Information

99.1 Joint Filing Agreement (incorporated by reference to Exhibit 99.1 to the Reporting Persons' Schedule 13G, filed with the SEC on November 13, 2025)