Monte Rosa: 5.5% Stake Reported by TCG/Chen Yu

Monte Rosa Therapeutics, Inc. Schedule 13G/A amendment reports that the Reporting Persons collectively hold 4,622,151 shares of Common Stock, representing 5.5% of the class based on 84,479,418 shares outstanding as of May 1, 2026.

Rhea-AI Filing Summary

Monte Rosa Therapeutics, Inc. Schedule 13G/A amendment reports that the Reporting Persons collectively hold 4,622,151 shares of Common Stock, representing 5.5% of the class based on 84,479,418 shares outstanding as of May 1, 2026. The holdings consist of two fund vehicles each holding 2,311,076 and 2,311,075 shares, and the reporting individual, Chen Yu, is disclosed as sharing voting and dispositive power through related general partner entities.

The filing clarifies ownership and voting/dispositive arrangements under Rule 13d-1(k)(1) and includes the reporting persons' address and organizational details. The statement notes potential shared voting and investment power among the named entities and that the Reporting Persons disclaim group status.

Insights

Institutional Ownership Specialist

Large holder reports a >5% stake via fund entities and shared control.

The filing documents that TCG Crossover II and TCG Crossover III each hold approximately 2,311,076 and 2,311,075 shares respectively, and that Chen Yu shares voting and dispositive power through the GP entities. The filing cites May 1, 2026 outstanding shares of 84,479,418 as the basis for the 5.5% figure.

Cash-flow treatment and transaction history are not provided in the excerpt; subsequent filings would show any changes. Filings of this type primarily update ownership disclosures and the structure of control affiliations.

Corporate Governance Analyst

Clarifies attribution and voting/dispositive relationships among funds, GPs, and an individual.

The statement attaches comments that the securities are held of record by fund entities and that GPs (TCG Crossover GP II/III) may be deemed to have voting and investment power. It also explains that the Reporting Persons expressly disclaim group status while filing jointly under Rule 13d-1(k)(1).

Key items to watch in future filings include any change in percent ownership relative to the May 1, 2026 outstanding share base and any amendments that alter voting or dispositive power.

Key Figures

Aggregate shares reported: 4,622,151 shares Per-fund holdings: 2,311,076 shares; 2,311,075 shares Shares outstanding used: 84,479,418 shares +1 more

4 metrics

Aggregate shares reported 4,622,151 shares Combined holdings reported for Reporting Persons

Per-fund holdings 2,311,076 shares; 2,311,075 shares Holdings for TCG Crossover II and TCG Crossover III respectively

Shares outstanding used 84,479,418 shares Outstanding as of <date>May 1, 2026</date> per issuer Form 10-Q

Percent of class 5.5% Percentage ownership for Chen Yu/Reporting Persons

Key Terms

beneficially owned, shared dispositive power, Rule 13d-1(k)(1)

3 terms

beneficially owned regulatory

"Consists of (i) 2,311,076 shares of Common Stock held of record by TCG Crossover II"

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 dispositive power regulatory

"Shared Dispositive Power 2,311,076.00"

Rule 13d-1(k)(1) regulatory

"agreement among the Reporting Persons to file jointly in accordance with the provisions of Rule 13d-1(k)(1)"

FAQ

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

What stake does GLUE filing show for Chen Yu and related funds?

The filing shows 4,622,151 shares beneficially owned collectively, representing 5.5% of the class based on May 1, 2026. This combines two fund positions of about 2,311,076 and 2,311,075 shares.

How was the 5.5% ownership calculated in the GLUE Schedule 13G/A?

The percentage uses 84,479,418 shares outstanding as of May 1, 2026, cited from the issuer's Form 10-Q. The filing divides the reported holdings by that outstanding share total.

Who holds voting and dispositive power over these GLUE shares?

The filing states that the securities are held of record by fund entities and that TCG Crossover GP II/III may be deemed to have voting and dispositive power, with Chen Yu as sole managing member sharing those powers.

Does the Schedule 13G/A assert a group status for these reporting persons for GLUE?

No. The filing expressly disclaims status as a group while attaching an agreement to file jointly under Rule 13d-1(k)(1), and clarifies each Reporting Person's limited beneficial ownership disclosures.

What address and organizational details are provided in the GLUE amendment?

The filing lists the Reporting Persons' principal business office as 245 Lytton Ave., Suite 350, Palo Alto, CA 94301, and states the entities are organized in Delaware with the reporting individual a U.S. citizen.

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

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Accepted by SEC EDGAR 05/15/2026 - 04:24 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Monte Rosa Therapeutics, Inc.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

61225M102

(CUSIP Number)

03/31/2026

(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): 61225M102

1

Names of Reporting Persons

TCG Crossover GP II, 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 2,311,076.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,311,076.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,311,076.00

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)

2.7 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover II (as defined in Item 2(a) below). TCG Crossover GP II (as defined in Item 2(a) below) is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 84,479,418 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer (as defined in Item 1(a) below) in its quarterly report on Form 10-Q filed with the Securities and Exchange Commission (the "Commission") on May 7, 2026 (the "Form 10-Q").

SCHEDULE 13G

CUSIP Number(s): 61225M102

1

Names of Reporting Persons

TCG Crossover Fund II, 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 2,311,076.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,311,076.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,311,076.00

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)

2.7 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover II. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 84,479,418 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer in the Form 10-Q.

SCHEDULE 13G

CUSIP Number(s): 61225M102

1

Names of Reporting Persons

TCG Crossover GP III, 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 2,311,075.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,311,075.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,311,075.00

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)

2.7 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover III (as defined in Item 2(a) below). TCG Crossover GP III (as defined in Item 2(a) below) is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 84,479,418 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer in the Form 10-Q.

SCHEDULE 13G

CUSIP Number(s): 61225M102

1

Names of Reporting Persons

TCG Crossover Fund III, 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 2,311,075.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,311,075.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,311,075.00

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)

2.7 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: These securities are held of record by TCG Crossover III. TCG Crossover GP III is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 84,479,418 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer in the Form 10-Q.

SCHEDULE 13G

CUSIP Number(s): 61225M102

1

Names of Reporting Persons

Chen Yu

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 4,622,151.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,622,151.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,622,151.00

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)

5.5 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: Consists of (i) 2,311,076 shares of Common Stock held of record by TCG Crossover II and (ii) 2,311,075 shares of Common Stock held of record by TCG Crossover III. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover II. TCG Crossover GP III is the general partner of TCG Crossover III and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover III. Chen Yu is the sole managing member of each of TCG Crossover GP II and TCG Crossover GP III and may be deemed to share voting, investment and dispositive power with respect to the securities held of record by TCG Crossover II and TCG Crossover III. Based on 84,479,418 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer in the Form 10-Q.

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: This Amendment No. 1 (Amendment No. 1) amends and supplements the Schedule 13G initially filed with the Commission on October 17, 2025 (the Original Schedule 13G) and is being filed by TCG Crossover Fund II, L.P. (TCG Crossover II), TCG Crossover GP II, LLC (TCG Crossover GP II), TCG Crossover Fund III, L.P. (TCG Crossover III) and TCG Crossover GP III, LLC (TCG Crossover GP III and together with TCG Crossover II, TCG Crossover GP II and TCG Crossover III, the Reporting Entities) and Chen Yu (the Reporting Individual). The Reporting Entities and the Reporting Individual are collectively referred to as the Reporting Persons. The Reporting Persons expressly disclaim status as a group for purposes of this Schedule 13G. The agreement among the Reporting Persons to file jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act is attached as Exhibit 1 to the Original Schedule 13G. Other than those securities reported herein as being held directly by such Reporting Person, each Reporting Person disclaims beneficial ownership of all securities reported in this Statement except to the extent of such Reporting Person's pecuniary interest therein. Capitalized terms not defined in this Amendment No. 1 have the meanings ascribed to them in the Original Schedule 13G.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each Reporting Person is 245 Lytton Ave., Suite 350, Palo Alto, CA 94301.
(c)	Citizenship: TCG Crossover GP II and TCG Crossover GP II are each a limited liability company organized under the laws of the State of Delaware. TCG Crossover II and TCG Crossover III are each a limited partnership organized under the laws of the State of Delaware. The Reporting Individual is a citizen of the United States of America.
(d)	Title of class of securities: Common Stock, par value $0.0001 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: See Row 9 of the cover page for each Reporting Person and the corresponding comments.
(b)	Percent of class: See Row 11 of the cover page for each Reporting Person and the corresponding comments.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Row 5 of the cover page for each Reporting Person and the corresponding comments.
	(ii) Shared power to vote or to direct the vote: See Row 6 of the cover page for each Reporting Person and the corresponding comments.
	(iii) Sole power to dispose or to direct the disposition of: See Row 7 of the cover page for each Reporting Person and the corresponding comments.
	(iv) Shared power to dispose or to direct the disposition of: See Row 8 of the cover page for each Reporting Person and the corresponding comments.
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. Under certain circumstances set forth in the limited partnership agreements of TCG Crossover II and TCG Crossover III and the limited liability company agreements of TCG Crossover GP II and TCG Crossover GP III, the general and limited partners or members, as the case may be, of each of such entities may be deemed to have the right to receive dividends from, or the proceeds from, the sale of securities of the Issuer owned by each such entity of which they are a partner or member, as the case may be.
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 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.

TCG Crossover GP II, LLC

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

TCG Crossover Fund II, L.P.

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

TCG Crossover GP III, LLC

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

TCG Crossover Fund III, L.P.

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	05/15/2026

Chen Yu

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, as Attorney-in-Fact for Chen Yu
Date:	05/15/2026