Q32 Bio investor Boxer Capital holds 13.3% stake

Q32 Bio Inc. has a large shareholder group led by Boxer Capital Management, LLC, Boxer Holdings, LP, Boxer Holdings GP, LLC, and Aaron Davis collectively reporting beneficial ownership of 3,149,310 shares of common stock as of June 30, 2026.

Rhea-AI Filing Summary

Q32 Bio Inc. has a large shareholder group led by Boxer Capital Management, LLC, Boxer Holdings, LP, Boxer Holdings GP, LLC, and Aaron Davis collectively reporting beneficial ownership of 3,149,310 shares of common stock as of June 30, 2026. This represents 13.30% of Q32 Bio’s outstanding common stock. The ownership is reported with shared voting and dispositive power over all 3,149,310 shares and no sole voting or dispositive power.

The percentage is calculated based on 23,681,415 shares outstanding, consisting of 16,956,415 shares outstanding as of May 1, 2026 plus 6,725,000 shares issued in a private placement that closed on May 28, 2026.

Insights

Equity ownership analyst

Boxer Capital reports a significant 13.3% passive stake in Q32 Bio.

The reporting group including Boxer Capital Management and affiliated entities discloses beneficial ownership of 3,149,310 Q32 Bio common shares, equal to 13.30% of the company as of June 30, 2026. All of these shares are held with shared, not sole, voting and dispositive power, indicating coordinated control across the reporting entities.

The ownership percentage is based on 23,681,415 shares outstanding, which includes 6,725,000 new shares issued in a private placement that closed on May 28, 2026. This suggests Boxer’s position is meaningful relative to the float, but the Schedule 13G format indicates a passive ownership posture rather than an activist stance.

Key Figures

Shares beneficially owned: 3,149,310 shares Ownership percentage: 13.30% Total shares outstanding used: 23,681,415 shares +2 more

5 metrics

Shares beneficially owned 3,149,310 shares Beneficial ownership by the Boxer Capital reporting group as of June 30, 2026

Ownership percentage 13.30% Percent of Q32 Bio common stock class beneficially owned as of June 30, 2026

Total shares outstanding used 23,681,415 shares Shares of Q32 Bio common stock outstanding used to calculate ownership percentage

Shares outstanding as of May 1, 2026 16,956,415 shares Q32 Bio common stock outstanding as of May 1, 2026 per Quarterly Report on Form 10-Q

Shares issued in private placement 6,725,000 shares Common stock issued in a private placement that closed on May 28, 2026

Key Terms

beneficially owned, shared voting power, shared dispositive power, private placement

4 terms

beneficially owned financial

"sets forth the aggregate number of shares of securities of the Issuer beneficially owned"

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.

shared voting power financial

"Shared Voting Power 3,149,310.00"

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 financial

"Shared Dispositive Power 3,149,310.00"

private placement financial

"shares of common stock issued in the private placement of equity securities"

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.

FAQ

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

How many Q32 Bio Inc. (QTTB) shares does Boxer Capital beneficially own?

The Boxer Capital reporting group beneficially owns 3,149,310 shares of Q32 Bio common stock as of June 30, 2026, with shared voting and dispositive power over all reported shares.

What percentage of Q32 Bio Inc. (QTTB) does the Boxer group hold?

The reporting persons collectively hold 13.30% of Q32 Bio’s outstanding common stock as of June 30, 2026, based on 23,681,415 shares outstanding used for the ownership calculation.

How was the 13.30% ownership in Q32 Bio Inc. (QTTB) calculated?

The 13.30% stake is based on 3,149,310 shares owned divided by 23,681,415 shares outstanding, which includes 16,956,415 shares as of May 1, 2026 plus 6,725,000 shares from a private placement closing May 28, 2026.

Does Boxer Capital have sole or shared voting power over Q32 Bio Inc. (QTTB) shares?

The reporting persons have 0 shares with sole voting power and 3,149,310 shares with shared voting power, matching their shared dispositive power, indicating coordinated control across the group.

What role did the May 28, 2026 private placement play in Q32 Bio Inc. (QTTB) ownership figures?

The ownership percentage uses a base of 23,681,415 shares, which includes 6,725,000 shares issued in a private placement of equity securities that closed on May 28, 2026, increasing total shares outstanding.

Who are the reporting persons in the Q32 Bio Inc. (QTTB) Schedule 13G filing?

The filing is jointly submitted by Boxer Capital Management, LLC, Boxer Holdings, LP, Boxer Holdings GP, LLC, and Aaron Davis, each sharing voting and dispositive power over the same 3,149,310 Q32 Bio shares.

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

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Accepted by SEC EDGAR 07/10/2026 - 04:34 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Q32 Bio Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

746964105

(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): 746964105

1

Names of Reporting Persons

Boxer Capital Management, 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 3,149,310.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,149,310.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,149,310.00

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)

13.30 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 746964105

1

Names of Reporting Persons

Boxer Holdings, LP

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 3,149,310.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,149,310.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,149,310.00

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)

13.30 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP Number(s): 746964105

1

Names of Reporting Persons

Boxer Holdings GP, 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 3,149,310.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,149,310.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,149,310.00

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)

13.30 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

CUSIP Number(s): 746964105

1

Names of Reporting Persons

Aaron Davis

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

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,149,310.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,149,310.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,149,310.00

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)

13.30 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Q32 Bio Inc.
(b)	Address of issuer's principal executive offices: 830 Winter Street, Waltham, MA 02451
Item 2.
(a)	Name of person filing: This statement is being jointly filed by (collectively, the "Reporting Persons"): Boxer Capital Management, LLC ("Boxer Capital") Boxer Holdings, LP Boxer Holdings GP, LLC Aaron Davis
(b)	Address or principal business office or, if none, residence: The business address of each Reporting Person is: 12860 El Camino Real, Suite 300, San Diego, CA 92130
(c)	Citizenship: Boxer Capital Management, LLC is a Delaware LLC. Boxer Holdings, LP is a Delaware LP. Boxer Holdings GP, LLC is a Delaware LLC. Aaron Davis is a citizen of the United States.
(d)	Title of class of securities: Common Stock, $0.0001 par value per share
(e)	CUSIP Number(s): 746964105
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: Row 9 of each Reporting Person's cover page to this Schedule 13G sets forth the aggregate number of shares of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
(b)	Percent of class: Row 11 of each Reporting Person's cover page to this Schedule 13G sets forth the percentages of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference. Such percentage is based upon 23,681,415 shares of the Issuer's Common Stock outstanding, which is comprised of 16,956,415 shares out as of May 1, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 5, 2026 plus 6,725,000 shares of common stock issued in the private placement of equity securities by the Issuer that closed on May 28, 2026.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Row 5 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(ii) Shared power to vote or to direct the vote: Row 6 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(iii) Sole power to dispose or to direct the disposition of: Row 7 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
	(iv) Shared power to dispose or to direct the disposition of: Row 8 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person as of June 30, 2026 and is incorporated by reference.
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.

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.

Boxer Capital Management, LLC

Signature:	/s/ Aaron Davis
Name/Title:	Boxer Capital Management, LLC, by Aaron Davis its Manager
Date:	07/10/2026

Boxer Holdings, LP

Signature:	/s/ Aaron Davis
Name/Title:	By Boxer Holdings, LP, by Boxer Holdings GP, LLC, its General Partner, by Aaron Davis its Manager
Date:	07/10/2026

Boxer Holdings GP, LLC

Signature:	/s/ Aaron Davis
Name/Title:	By Boxer Holdings GP, LLC by Aaron Davis, its Manager
Date:	07/10/2026

Aaron Davis

Signature:	/s/ Aaron Davis
Name/Title:	By Aaron Davis, an individual
Date:	07/10/2026