IGMS Merger: Baker Bros. Sells Stake for $1.247 Plus CVR

Rhea-AI Filing Summary

Amendment No. 8 to Schedule 13D reports that Baker Bros. Advisors LP, Baker Bros. Advisors (GP) LLC, Julian C. Baker and Felix J. Baker (the Reporting Persons) no longer beneficially own any securities of IGM Biosciences, Inc. (IGMS) following the closing of a merger on August 14, 2025. Under the Merger Agreement, each share of common and non-voting common stock was exchanged for $1.247 in cash plus one non-transferable contingent value right. Prefunded warrants converted to the merger consideration net of exercise costs and stock options were cancelled for no value. Felix J. Baker resigned from the board prior to the merger.

Positive

• Full liquidity for previously held shares: Reporting Persons received $1.247 cash per share plus one CVR, providing immediate realized value.
• Prefunded warrants converted: Prefunded warrants converted into the merger consideration net of exercise costs, simplifying capitalization.

Negative

• Loss of ownership and influence: Reporting Persons now beneficially own 0% of IGMS, ceasing to be >5% owners and removing investor influence.
• Options cancelled for no value: Previously reported stock options were cancelled without consideration, eliminating potential upside for option holders.
• Director resignation: Felix J. Baker resigned from the board prior to the merger, representing a governance departure.

Insights

Financial Analyst

TL;DR: Reporting persons disposed of all IGMS holdings in the merger; transaction removes their ownership but provides cash plus CVRs to holders.

The filing documents a full disposition of equity and related instruments by the Reporting Persons as part of a merger that paid $1.247 per share in cash plus one contingent value right per share. Prefunded warrants converted into the merger consideration net of exercise costs, and outstanding stock options were cancelled for no value, reducing outstanding contingent claims. The Reporting Persons now hold 0% of the company, which eliminates their economic and voting exposure to IGMS.

Corporate Governance Expert

TL;DR: Complete exit and director resignation materially reduce Baker group influence over IGMS governance and strategic direction.

The filing confirms Felix J. Baker resigned as a director immediately prior to the merger and that the Baker entities ceased to own more than 5% of IGMS. This is a material governance change because it removes the Reporting Persons' ability to influence board composition or corporate strategy going forward. Cancellation of options for no value also terminates former management alignment via equity incentives.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 8)

IGM Biosciences, Inc.

(Name of Issuer)

Common Stock, $0.01 par value per share

(Title of Class of Securities)

449585108

(CUSIP Number)

Alexandra A. Toohey, CFO
860 Washington Street, 3rd Floor,
New York, NY, 10014
212-339-5690

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

08/14/2025

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No. 449585108

1

Name of reporting person

Baker Bros. Advisors LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP No. 449585108

1

Name of reporting person

Baker Bros. Advisors (GP) LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13D

CUSIP No. 449585108

1

Name of reporting person

Julian C. Baker

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

CUSIP No. 449585108

1

Name of reporting person

Felix J. Baker

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, $0.01 par value per share
(b)	Name of Issuer: IGM Biosciences, Inc.
(c)	Address of Issuer's Principal Executive Offices: 3 East Third Avenue, Suite 200, San Mateo, CALIFORNIA , 94401.
Item 1 Comment: This Amendment No. 8 to Schedule 13D amends and supplements the previously filed Schedule 13D filed by Baker Bros. Advisors LP (the "Adviser"), Baker Bros. Advisors (GP) LLC (the "Adviser GP"), Julian C. Baker and Felix J. Baker (collectively, the "Reporting Persons"). Except as supplemented herein, such statements, as heretofore amended and supplemented, remain in full force and effect. The Adviser GP is the sole general partner of the Adviser. Pursuant to management agreements, as amended, among the Adviser, Baker Brothers Life Sciences, L.P. ("Life Sciences") and 667, L.P. ("667", and together with Life Sciences, the "Funds"), and their respective general partners, the Funds' respective general partners relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds, and thus the Adviser has complete and unlimited discretion and authority with respect to the Funds' investments and voting power over investments. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D, as amended. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable.
Item 4.	Purpose of Transaction
	Item 4 of the Schedule 13D is supplemented and amended, as the case may be, as follows: This Amendment No. 8 is being filed to report the disposition of shares of the common stock ("Common Stock") of IGM Biosciences, Inc. (the "Issuer"), shares of non-voting common stock of the Issuer that were convertible at any time at the option of the holder on a 1-for-1 basis without consideration into Common Stock ("Non-Voting Common Stock"), prefunded warrants of the Issuer that were exercisable on a 1-for-1 basis at any time at the option of the holder with no expiration date to purchase Common Stock at an exercise price of $0.01 per share ("Prefunded Warrants") and non-qualified options to purchase Common Stock ("Stock Options"), in connection with the consummation of the transactions (the "Merger") contemplated by the Agreement and Plan of Merger, dated as of July 1, 2025 (the "Merger Agreement"), by and among the Issuer, Concentra Biosciences, LLC (the "Parent") and Concentra Merger Sub V, Inc. ("Merger Sub"), a wholly owned subsidiary of Parent, pursuant to which, at the effective time of the Merger on August 14, 2025 (the "Effective Time"), Merger Sub merged with and into the Issuer, with the Issuer surviving as a wholly owned subsidiary of Parent. Pursuant to the Merger Agreement, on August 14, 2025, Parent completed a tender offer to purchase each issued and outstanding share of Common Stock and Non-Voting Common Stock in exchange for (i) $1.247 in cash per share of Common Stock or Non-Voting Common Stock plus (ii) one non-transferable contractual contingent value right (each a "CVR") for each share of Common Stock or Non-Voting Common Stock (the "Merger Consideration"). Immediately after the Effective Time, each Prefunded Warrant was converted into a right to receive the Merger Consideration, net of any cost of exercise. Also, immediately after the Effective Time, all previously reported Stock Options were cancelled by the Issuer for no value received. Pursuant to the Merger Agreement, at the Effective Time, 667 and Life Sciences disposed of 332,848 and 3,739,162 shares of Common Stock, respectively, and 834,707 and 9,886,217 shares of Non-Voting Common Stock, respectively, Felix J. Baker disposed of 12,098 shares of Common Stock held directly for the benefit of the Funds and the Advisor disposed of 12,102 shares of Common Stock directly held for the benefit of the Funds, in exchange for the Merger Consideration. In addition, immediately after the Effective Time pursuant to the Merger, 667 and Life Sciences disposed of 49,820 and 616,846 Prefunded Warrants in exchange for the Merger Consideration less any cost of exercise of the Prefunded Warrants. Immediately prior to the Effective Time, Felix J. Baker resigned as a director of the Issuer. On June 30, 2025, Felix J. Baker was granted 953 restricted stock units (each, an "RSU") for his previous service on the board of directors of the Issuer (the "Board") pursuant to the Issuer's Outside Director Compensation Plan in lieu of director retainer fees of $11,500. These RSUs were accelerated pursuant to the Merger Agreement and were disposed of in the Merger as part of the 12,098 shares of Common Stock directly held by Felix J. Baker described above.
Item 5.	Interest in Securities of the Issuer
(a)	The disclosure in Item 4 is incorporated by reference herein. Item 5 of the Schedule 13D is amended and restated as follows: Items 7 through 11 and 13 of each of the cover pages of this Amendment No. 8 are incorporated herein by reference. The Reporting Persons no longer beneficially own any securities of the Issuer.
(b)	The Reporting Persons no longer beneficially own any securities of the Issuer.
(c)	(c) The disclosure in Item 4 is incorporated herein by reference. Other than as disclosed in this Schedule 13D, as amended, none of the Reporting Persons or their affiliates has affected any transactions in securities of the Issuer during the past 60 days.
(d)	(d) Certain securities of the Issuer were held directly by 667, a limited partnership the sole general partner of which is Baker Biotech Capital, L.P., a limited partnership the sole general partner of which is Baker Biotech Capital (GP), LLC. Julian C. Baker and Felix J. Baker are the managing members of Baker Biotech Capital (GP), LLC. Certain securities of the Issuer were held directly by Life Sciences, a limited partnership the sole general partner of which is Baker Brothers Life Sciences Capital, L.P., a limited partnership the sole general partner of which is Baker Brothers Life Sciences Capital (GP), LLC. Julian C. Baker and Felix J. Baker are the managing members of Baker Brothers Life Sciences Capital (GP), LLC.
(e)	(e) On August 14, 2025, the Reporting Persons ceased to be the beneficial owners of more than five percent of the Common Stock of the Issuer.

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.

Baker Bros. Advisors LP

Signature:	/s/ Scott L. Lessing
Name/Title:	By: Baker Bros. Advisors (GP) LLC, its general partner Scott L. Lessing/ President
Date:	08/18/2025

Baker Bros. Advisors (GP) LLC

Signature:	/s/ Scott L. Lessing
Name/Title:	Scott L. Lessing/ President
Date:	08/18/2025

Julian C. Baker

Signature:	/s/ Julian C. Baker
Name/Title:	Julian C. Baker
Date:	08/18/2025

Felix J. Baker

Signature:	/s/ Felix J. Baker
Name/Title:	Felix J. Baker
Date:	08/18/2025

FAQ

What did the Baker reporting persons receive for their IGM Biosciences (IGMS) shares?

They received $1.247 in cash per share plus one non-transferable contingent value right (CVR) per share as merger consideration.

Do the Reporting Persons still own any IGMS securities after Amendment No. 8?

No. The filing states the Reporting Persons no longer beneficially own any securities of IGM Biosciences.

What happened to prefunded warrants and stock options held by the Reporting Persons?

Prefunded warrants were converted into the merger consideration net of any exercise cost; stock options were cancelled for no value.

Did any Reporting Person resign from the IGM Biosciences board?

Yes. Felix J. Baker resigned as a director immediately prior to the merger effective time.

When did the merger that triggered this Schedule 13D/A take effect?

The merger's effective time and related dispositions occurred on August 14, 2025.