Atlas Venture fund discloses 625,000 Q32 Bio (QTTB) common shares held

Rhea-AI Filing Summary

Q32 Bio Inc. disclosed that Atlas Venture Opportunity Fund III, L.P. holds 625,000 shares of its common stock in an initial beneficial ownership report. Related general partners Atlas Venture Associates Opportunity III, L.P. and Atlas Venture Associates Opportunity III, LLC disclaim beneficial ownership except for any pecuniary interest.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Atlas Venture Opportunity Fund Ill, L.P., Atlas Venture Associates Opportunity III, L.P., Atlas Venture Associates Opportunity III, LLC

Role null | null | null

Type	Security	Shares	Price	Value
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 625,000 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Beneficially owned shares: 625,000 shares

1 metrics

Beneficially owned shares 625,000 shares Common Stock held by Atlas Venture Opportunity Fund III, L.P.

Key Terms

beneficial ownership, pecuniary interest, general partner

3 terms

beneficial ownership financial

"disclaims beneficial ownership of the securities held by AVOF III"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"except to the extent of its pecuniary interest therein, if any"

general partner financial

"Atlas Venture Associates Opportunity III, L.P. is the general partner of AVOF III"

A general partner is the person or firm that runs an investment partnership and legally represents it — they make the day-to-day decisions, choose which assets to buy or sell, and are responsible for the partnership’s obligations. Investors care because the general partner’s judgment, risk-taking and fee and profit-sharing arrangements determine both the potential returns and the level of exposure to losses; think of the GP as the ship’s captain whose skill and honesty shape the voyage’s outcome.

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Understanding Insider Trading Forms →

Available on EDGAR 06/08/2026 - 04:30 PM Accepted by SEC EDGAR 06/08/2026 - 04:30 PM Learn about SEC filing dates

SEC 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

OMB APPROVAL

OMB Number:			3235-0104
Estimated average burden
hours per response:			0.5

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)

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)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

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)

FAQ

What did Atlas Venture report in its Q32 Bio (QTTB) Form 3 filing?

Atlas Venture Opportunity Fund III, L.P. reported beneficial ownership of 625,000 shares of Q32 Bio common stock. This Form 3 serves as an initial statement of ownership when an entity becomes subject to insider reporting requirements.

How many Q32 Bio (QTTB) shares does Atlas Venture Opportunity Fund III hold?

Atlas Venture Opportunity Fund III, L.P. holds 625,000 shares of Q32 Bio common stock. This amount reflects its reported beneficial ownership position following the reporting date in the Form 3 filing with the SEC.

What is the role of Atlas Venture Associates entities in Q32 Bio (QTTB) ownership?

Atlas Venture Associates Opportunity III, L.P. and Atlas Venture Associates Opportunity III, LLC act as general partners of the fund that owns Q32 Bio shares. They each disclaim beneficial ownership except to the extent of any pecuniary interest they may have in the fund’s holdings.

Does the Q32 Bio (QTTB) Form 3 show recent insider buying or selling?

The Form 3 does not show recent insider buying or selling activity. It reports a holding entry indicating that Atlas Venture Opportunity Fund III, L.P. beneficially owns 625,000 Q32 Bio common shares as of the reporting date.

Why is Q32 Bio (QTTB) required to disclose Atlas Venture’s holdings?

Q32 Bio must disclose Atlas Venture’s holdings because the fund became subject to insider reporting rules. Form 3 provides an initial snapshot of beneficial ownership, helping investors understand significant positions in the company’s common stock.