Q32 Bio Inc. ownership disclosure: a group of affiliated entities led by Biotechnology Value Fund, L.P. and related entities reported coordinated holdings representing up to 2,367,524 shares (aggregate) and certain beneficial ownership positions in Q32 Bio common stock. As of the close of business on June 4, 2026, BVF held 1,248,973 shares (5.3%), BVF2 held 929,003 shares (3.9%), and Biotechnology Value Trading Fund OS held 155,156 shares (<1%).
The filing also discloses 150,000 pre-funded warrants exercisable into shares; an Ownership Limit of 9.99% restricts exercises, limiting exercisable pre-funded warrants to 17,524 shares for the reporting group as of June 4, 2026. Several entities in the group disclaim beneficial ownership of other group members' shares; BVF GP, BVF2 GP, BVF GPH, Partners, BVF Inc. and Mark N. Lampert are named as related controlling or deemed owners in the schedule.
Positive
None.
Negative
None.
Insights
Large institutional position disclosed with pre-funded warrants and a 9.99% ownership cap.
The filing lists an aggregate visible position across affiliated entities of 2,367,524 shares and identifies 150,000 pre-funded warrants exercisable into common shares. The Ownership Limit is stated as 9.99%, constraining immediate exercises to 17,524 shares for the group as of June 4, 2026.
Cash‑flow treatment and timing of any warrant exercises are not described in the excerpt; subsequent filings or transactions would determine whether the group converts warrants into voting stock or adjusts holdings.
Key Figures
BVF shares beneficially owned:1,248,973 sharesBVF2 shares beneficially owned:929,003 sharesTrading Fund OS shares beneficially owned:155,156 shares+4 more
7 metrics
BVF shares beneficially owned1,248,973 sharesAs of June 4, 2026; approximately 5.3% of class
BVF2 shares beneficially owned929,003 sharesAs of June 4, 2026; approximately 3.9% of class
Trading Fund OS shares beneficially owned155,156 sharesAs of June 4, 2026; less than 1% of class
Aggregate shares attributed to Partners/BVF Inc./Lampert2,367,524 sharesAs of June 4, 2026; approx. 9.99% of class
Pre-Funded Warrants exercisable150,000 warrantsAggregate held by reporting persons as of June 4, 2026
Exercise limit under Ownership Limit17,524 sharesMaximum exercisable of pre-funded warrants given 9.99% cap as of June 4, 2026
Shares outstanding denominator components16,956,415 sharesOutstanding as of May 1, 2026 (per Form 10-Q)
"the Reporting Persons and a certain Partners managed account (the "Partners Managed Account") held pre-funded warrants"
Pre-funded warrants are financial instruments that give investors the right to purchase a company's stock at a set price, but with most or all of the purchase price paid upfront. They function like a coupon or gift card for stock, allowing investors to buy shares later at a fixed price, which can be beneficial if they want to avoid future price increases. This makes them important for investors seeking flexibility and certainty in their investment plans.
Ownership Limitregulatory
"A holder of a Pre-Funded Warrant may not exercise such Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% (the "Ownership Limit")"
Beneficially ownedfinancial
"BVF beneficially owned 1,248,973 Shares, including 17,524 Shares underlying certain Pre-Funded Warrants"
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.
BVF reports beneficial ownership of 1,248,973 shares, representing approximately 5.3% of outstanding shares as of June 4, 2026. This figure includes 17,524 shares underlying exercisable pre-funded warrants held by BVF.
How many pre-funded warrants does the reporting group hold?
The reporting persons and a Partners managed account hold an aggregate of 150,000 pre-funded warrants exercisable into common stock. An Ownership Limit of 9.99% restricts near-term exercises to 17,524 shares as of June 4, 2026.
What aggregate share counts do affiliated entities report?
Affiliated entities report aggregate beneficial positions of 2,177,976 shares held by BVF and BVF2 combined, and 2,367,524 shares when including holdings attributed to Partners and the Partners Managed Account as of June 4, 2026.
What denominator was used to calculate the ownership percentages?
Percentages are calculated using a denominator that sums 16,956,415 shares outstanding as of May 1, 2026, 6,725,000 shares issued under a May 26, 2026 purchase agreement, and 17,524 shares issuable upon exercise of certain pre-funded warrants.
Does Mark N. Lampert directly own the reported shares?
Mark N. Lampert is disclosed as a reporting person who may be deemed to beneficially own 2,367,524 shares through his relationships with BVF Inc. and affiliated entities; the filing includes disclaimers that several entities disclaim beneficial ownership of other group members' shares.
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, par value $0.0001 per share
(Title of Class of Securities)
746964105
(CUSIP Number)
05/28/2026
(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
BIOTECHNOLOGY VALUE FUND 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
1,248,973.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,248,973.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,248,973.00
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)
5.3 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BVF I 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
1,248,973.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,248,973.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,248,973.00
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)
5.3 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BIOTECHNOLOGY VALUE FUND II 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
929,003.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
929,003.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
929,003.00
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)
3.9 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BVF II 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
929,003.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
929,003.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
929,003.00
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)
3.9 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
Biotechnology Value Trading Fund OS 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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
155,156.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
155,156.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
155,156.00
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):
746964105
1
Names of Reporting Persons
BVF Partners OS Ltd.
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
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
155,156.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
155,156.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
155,156.00
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)
CO
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BVF GP HOLDINGS 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
2,177,976.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,177,976.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,177,976.00
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)
9.2 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BVF PARTNERS L P/IL
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
2,367,524.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,367,524.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,367,524.00
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)
9.99 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
BVF INC/IL
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
2,367,524.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,367,524.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,367,524.00
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)
9.99 %
12
Type of Reporting Person (See Instructions)
CO
SCHEDULE 13G
CUSIP Number(s):
746964105
1
Names of Reporting Persons
LAMPERT MARK N
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
2,367,524.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,367,524.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,367,524.00
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)
9.99 %
12
Type of Reporting Person (See Instructions)
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:
Biotechnology Value Fund, L.P. ("BVF")
BVF I GP LLC ("BVF GP")
Biotechnology Value Fund II, L.P. ("BVF2")
BVF II GP LLC ("BVF2 GP")
Biotechnology Value Trading Fund OS LP ("Trading Fund OS")
BVF Partners OS Ltd. ("Partners OS")
BVF GP Holdings LLC ("BVF GPH")
BVF Partners L.P. ("Partners")
BVF Inc.
Mark N. Lampert ("Mr. Lampert")
Each of the foregoing is referred to as a "Reporting Person" and collectively as the "Reporting Persons."
(b)
Address or principal business office or, if none, residence:
Biotechnology Value Fund, L.P.
44 Montgomery St., 40th Floor
San Francisco, California 94104
BVF I GP LLC
44 Montgomery St., 40th Floor
San Francisco, California 94104
Biotechnology Value Fund II, L.P.
44 Montgomery St., 40th Floor
San Francisco, California 94104
BVF II GP LLC
44 Montgomery St., 40th Floor
San Francisco, California 94104
Biotechnology Value Trading Fund OS LP
PO Box 309 Ugland House
Grand Cayman, KY1-1104
Cayman Islands
BVF Partners OS Ltd.
PO Box 309 Ugland House
Grand Cayman, KY1-1104
Cayman Islands
BVF GP Holdings LLC
44 Montgomery St., 40th Floor
San Francisco, California 94104
BVF Partners L.P.
44 Montgomery St., 40th Floor
San Francisco, California 94104
BVF Inc.
44 Montgomery St., 40th Floor
San Francisco, California 94104
Mark N. Lampert
44 Montgomery St., 40th Floor
San Francisco, California 94104
(c)
Citizenship:
Biotechnology Value Fund, L.P.
Delaware
BVF I GP LLC
Delaware
Biotechnology Value Fund II, L.P.
Delaware
BVF II GP LLC
Delaware
Biotechnology Value Trading Fund OS LP
Cayman Islands
BVF Partners OS Ltd.
Cayman Islands
BVF GP Holdings LLC
Delaware
BVF Partners L.P.
Delaware
BVF Inc.
Delaware
Mark N. Lampert
United States
(d)
Title of class of securities:
Common Stock, par value $0.0001 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:
As of the close of business on June 4, 2026, the Reporting Persons and a certain Partners managed account (the "Partners Managed Account") held pre-funded warrants (the "Pre-Funded Warrants") exercisable for an aggregate of 150,000 shares of the Issuer's Common Stock, par value $0.0001 per share (the "Shares"). The Pre-Funded Warrants are exercisable at any time after the date of issuance and will expire when exercised in full. A holder of a Pre-Funded Warrant may not exercise such Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% (the "Ownership Limit") of the number of Shares outstanding immediately after giving effect to such exercise. As of the close of business on June 4, 2026, the Ownership Limit limits the exercise of the Pre-Funded Warrants held by the Reporting Persons and the Partners Managed Account to 17,524 out of the 150,000 Shares underlying the Pre-Funded Warrants held by them.
As of the close of business on June 4, 2026, (i) BVF beneficially owned 1,248,973 Shares, including 17,524 Shares underlying certain Pre-Funded Warrants held by it and excluding 61,079 Shares underlying certain Pre-Funded Warrants held by it, (ii) BVF2 beneficially owned 929,003 Shares, excluding 59,298 Shares underlying the Pre-Funded Warrants held by it, and (iii) Trading Fund OS beneficially owned 155,156 Shares, excluding 9,904 Shares underlying the Pre-Funded Warrants held by it.
BVF GP, as the general partner of BVF, may be deemed to beneficially own the 1,248,973 Shares beneficially owned by BVF.
BVF2 GP, as the general partner of BVF2, may be deemed to beneficially own the 929,003 Shares beneficially owned by BVF2.
Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 155,156 Shares beneficially owned by Trading Fund OS.
BVF GPH, as the sole member of each of BVF GP and BVF2 GP, may be deemed to beneficially own the 2,177,976 Shares beneficially owned in the aggregate by BVF and BVF2.
Partners, as the investment manager of BVF, BVF2 and Trading Fund OS, and the sole member of Partners OS, may be deemed to beneficially own the 2,367,524 Shares beneficially owned in the aggregate by BVF, BVF2 and Trading Fund OS and held in the Partners Managed Account, including 34,392 Shares held in the Partners Managed Account, which excludes 2,195 Shares underlying the Pre-Funded Warrants held in the Partners Managed Account.
BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 2,367,524 Shares beneficially owned by Partners.
Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 2,367,524 Shares beneficially owned by BVF Inc.
The foregoing should not be construed in and of itself as an admission by any Reporting Person as to beneficial ownership of any Shares owned by another Reporting Person. BVF GP disclaims beneficial ownership of the Shares beneficially owned by BVF. BVF2 GP disclaims beneficial ownership of the Shares beneficially owned by BVF2. Partners OS disclaims beneficial ownership of the Shares beneficially owned by Trading Fund OS. BVF GPH disclaims beneficial ownership of the Shares beneficially owned by BVF and BVF2. Each of Partners, BVF Inc. and Mr. Lampert disclaims beneficial ownership of the Shares beneficially owned by BVF, BVF2 and Trading Fund OS and held in the Partners Managed Account, and the filing of this statement shall not be construed as an admission that any such person or entity is the beneficial owner of any such securities.
(b)
Percent of class:
The following percentages are based upon a denominator that is the sum of: (i) 16,956,415 Shares outstanding 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, (ii) 6,725,000 Shares issued and sold by the Issuer pursuant to a Securities Purchase Agreement, dated May 26, 2026, as set forth in the Issuer's Current Report on Form 8-K filed with the Securities and Exchange Commission on May 27, 2026, and (iii) 17,524 Shares issuable upon the exercise of certain Pre-Funded Warrants held by the Reporting Persons, as applicable.
As of the close of business on June 4, 2026, (i) BVF beneficially owned approximately 5.3% of the outstanding Shares, (ii) BVF2 beneficially owned approximately 3.9% of the outstanding Shares, (iii) Trading Fund OS beneficially owned less than 1% of the outstanding Shares, (iv) BVF GP may be deemed to beneficially own approximately 5.3% of the outstanding Shares, (v) BVF2 GP may be deemed to beneficially own approximately 3.9% of the outstanding Shares, (vi) Partners OS may be deemed to beneficially own less than 1% of the outstanding Shares, (vii) BVF GPH may be deemed to beneficially own approximately 9.2% of the outstanding Shares, and (viii) each of Partners, BVF Inc. and Mr. Lampert may be deemed to beneficially own approximately 9.99% of the outstanding Shares (less than 1% of the outstanding Shares are held in the Partners Managed Account).
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
See Cover Pages Items 5-9.
(ii) Shared power to vote or to direct the vote:
See Cover Pages Items 5-9.
(iii) Sole power to dispose or to direct the disposition of:
See Cover Pages Items 5-9.
(iv) Shared power to dispose or to direct the disposition of:
See Cover Pages Items 5-9.
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.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
BVF GP, BVF GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by BVF. BVF GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by BVF2. Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by Trading Fund OS and held in the Partners Managed Account.
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.
If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(K), so indicate under Item 3(k) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group.
See Exhibit 99.1.
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 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.
