SEC FORM 3

SEC FORM 3SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Atlas Venture Opportunity Fund Ill, L.P.

(Last)

(First)

(Middle)

ATLAS VENTURE

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE

MASSACHUSETTS

02139

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
05/26/2026

3. Issuer Name and Ticker or Trading Symbol
Q32 Bio Inc. [ QTTB ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

Director		10% Owner
Officer (give title below)	X	Other (specify below)
		See Remarks

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	625,000	D⁽¹⁾

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)

1. Name and Address of Reporting Person^*

Atlas Venture Opportunity Fund Ill, L.P.

(Last)

(First)

(Middle)

ATLAS VENTURE

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE

MASSACHUSETTS

02139

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director		10% Owner
Officer (give title below)	X	Other (specify below)
		See Remarks

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity III, L.P.

(Last)

(First)

(Middle)

300 TECHNOLOGY SQ., 8TH FLOOR

(Street)

CAMBRIDGE

MASSACHUSETTS

02139

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director		10% Owner
Officer (give title below)	X	Other (specify below)
		See Remarks

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity III, LLC

(Last)

(First)

(Middle)

300 TECHNOLOGY SQ., 8TH FLOOR

(Street)

CAMBRIDGE

MASSACHUSETTS

02139

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director		10% Owner
Officer (give title below)	X	Other (specify below)
		See Remarks

Explanation of Responses:

1. The shares are owned directly by Atlas Venture Opportunity Fund III, L.P. ("AVOF III"). Atlas Venture Associates Opportunity III, L.P. ("AVAO III LP") is the general partner of AVOF III. Atlas Venture Associates Opportunity III, LLC ("AVAO III LLC") is the general partner of AVAO III LP. Each of AVAO III LP and AVAO III LLC disclaims beneficial ownership of the securities held by AVOF III, except to the extent of its pecuniary interest therein, if any.

Remarks:

The Reporting Persons are under common control with other entities affiliated with Atlas Venture who, together with the Reporting Persons, collectively beneficially own in the aggregate greater than 10% of the outstanding common stock of the Issuer. The Reporting Persons may be deemed to be members of a "group" with such other entities for purposes of Section 13 of the Exchange Act. However, the Reporting Persons disclaim such group membership, and this Form 3 shall not be deemed an admission that the Reporting Persons are members of a group for purposes of Section 13 of the Exchange Act or for any other purposes.

	Atlas Venture Opportunity Fund III, L.P., By: Atlas Venture Associates Opportunity III, L.P., its general partner, By: Atlas Venture Associates Opportunity III, LLC, its general partner, By: /s/ Ommer Chohan, Chief Financial Officer	06/08/2026
	Atlas Venture Associates Opportunity III, L.P., By: Atlas Venture Associates Opportunity III, LLC, its general partner, By: /s/ Ommer Chohan, Chief Financial Officer	06/08/2026
	Atlas Venture Associates Opportunity III, LLC, By: /s/ Ommer Chohan, Chief Financial Officer	06/08/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 3: SEC 1473 (03-26)

New insider Atlas Venture Opportunity Fund Ill, L.P. claimed ownership of 625,000 shares (SEC Form 3)