Monte Rosa Therapeutics, Inc. received an updated ownership report from a group of investment entities associated with Biotechnology Value Fund and Mark N. Lampert. As of December 31, 2025, these Reporting Persons may be deemed to beneficially own a total of 3,835,886 shares of Monte Rosa common stock, representing approximately 5.9% of the 65,117,761 shares outstanding as of October 31, 2025. Individual funds hold portions of this stake, including 2,050,405 shares at Biotechnology Value Fund, 1,496,859 shares at Biotechnology Value Fund II, and 232,097 shares at Biotechnology Value Trading Fund OS. The filing states the shares were not acquired and are not held for the purpose of changing or influencing control of the company.
Positive
None.
Negative
None.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 2)
Monte Rosa Therapeutics, Inc.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
61225M102
(CUSIP Number)
12/31/2025
(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)
SCHEDULE 13G
CUSIP No.
61225M102
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
2,050,405.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,050,405.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,050,405.00
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)
3.1 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP No.
61225M102
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
2,050,405.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
2,050,405.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
2,050,405.00
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)
3.1 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP No.
61225M102
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
1,496,859.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,496,859.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,496,859.00
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)
2.3 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP No.
61225M102
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
1,496,859.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,496,859.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,496,859.00
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)
2.3 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP No.
61225M102
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
232,097.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
232,097.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
232,097.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
PN
SCHEDULE 13G
CUSIP No.
61225M102
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
232,097.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
232,097.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
232,097.00
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)
0.4 %
12
Type of Reporting Person (See Instructions)
CO
SCHEDULE 13G
CUSIP No.
61225M102
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
3,547,264.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,547,264.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,547,264.00
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)
5.4 %
12
Type of Reporting Person (See Instructions)
OO
SCHEDULE 13G
CUSIP No.
61225M102
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
3,835,886.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,835,886.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,835,886.00
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)
5.9 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP No.
61225M102
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
3,835,886.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,835,886.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,835,886.00
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)
5.9 %
12
Type of Reporting Person (See Instructions)
CO
SCHEDULE 13G
CUSIP No.
61225M102
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
3,835,886.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
3,835,886.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
3,835,886.00
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)
5.9 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Monte Rosa Therapeutics, Inc.
(b)
Address of issuer's principal executive offices:
321 HARRISON AVENUE, SUITE 900, BOSTON, MA 02118
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, $0.0001 par value per share
(e)
CUSIP No.:
61225M102
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 December 31, 2025, (i) BVF beneficially owned 2,050,405 shares of the Issuer's Common Stock, $0.0001 par value per share (the "Shares"), (ii) BVF2 beneficially owned 1,496,859 Shares and (iii) Trading Fund OS beneficially owned 232,097 Shares.
BVF GP, as the general partner of BVF, may be deemed to beneficially own the 2,050,405 Shares beneficially owned by BVF.
BVF2 GP, as the general partner of BVF2, may be deemed to beneficially own the 1,496,859 Shares beneficially owned by BVF2.
Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 232,097 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 3,547,264 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 3,835,886 Shares beneficially owned in the aggregate by BVF, BVF2 and Trading Fund OS and held in a certain Partners managed account (the "Partners Managed Account"), including 56,525 Shares held in the Partners Managed Account.
BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 3,835,886 Shares beneficially owned by Partners.
Mr. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 3,835,886 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 on 65,117,761 Shares outstanding as of October 31, 2025, which is the total number of Shares outstanding as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2025.
As of the close of business on December 31, 2025, (i) BVF beneficially owned approximately 3.1% of the outstanding Shares, (ii) BVF2 beneficially owned approximately 2.3% 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 3.1% of the outstanding Shares, (v) BVF2 GP may be deemed to beneficially own approximately 2.3% 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 5.4% of the outstanding Shares, and (viii) each of Partners, BVF Inc. and Mr. Lampert may be deemed to beneficially own approximately 5.9% 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 GPH, Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the Shares beneficially owned by BVF and 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)(J), so indicate under Item 3(j) 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 to the Schedule 13G filed with the Securities and Exchange Commission on January 31, 2025.
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.
What ownership stake in Monte Rosa Therapeutics (GLUE) is reported in this Schedule 13G/A?
The reporting group discloses beneficial ownership of about 3,835,886 shares, or approximately 5.9% of Monte Rosa’s outstanding common stock. This percentage is based on 65,117,761 shares outstanding as of October 31, 2025.
Who are the main investors reporting shares of Monte Rosa Therapeutics (GLUE)?
Key investors include Biotechnology Value Fund, L.P., Biotechnology Value Fund II, L.P., Biotechnology Value Trading Fund OS LP, related general partners and managers, and Mark N. Lampert, who may be deemed to share beneficial ownership through these entities.
How many Monte Rosa (GLUE) shares are held by each BVF fund?
As of December 31, 2025, Biotechnology Value Fund holds 2,050,405 shares, Biotechnology Value Fund II holds 1,496,859 shares, and Biotechnology Value Trading Fund OS holds 232,097 shares of Monte Rosa common stock, according to the ownership disclosure.
Does the BVF group intend to influence control of Monte Rosa Therapeutics (GLUE)?
The filing certifies the securities were not acquired and are not held for changing or influencing control of Monte Rosa. It states they are not held in connection with any transaction having that purpose, other than activities tied to a specific nomination rule.
How is Mark N. Lampert related to the Monte Rosa (GLUE) share ownership?
The filing states Mark N. Lampert, as a director and officer of BVF Inc., may be deemed to beneficially own the 3,835,886 shares attributed to BVF-managed entities. It also notes various Reporting Persons disclaim beneficial ownership of shares held by related entities.
What share count did the BVF group use to calculate its 5.9% stake in GLUE?
The reported ownership percentages use 65,117,761 Monte Rosa shares outstanding as of October 31, 2025. This figure comes from Monte Rosa’s Form 10-Q and is the baseline for calculating each Reporting Person’s percentage interest.
