BAKER BROS. ADVISORS LP - 14 Aug 2025 Form 4 Insider Report for IGM Biosciences, Inc. (IGMS)

Reporting relationship: Former 10% owner and director
Issuer ticker: IGMS
Reported as of: 14 Aug 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 18 Aug 2025, 17:39:42 UTC
Prior SEC filing: 01 Aug 2025
Next SEC filing: 20 Aug 2025
Source filing: View source filing
Reporting owner signature: By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing

Key filing fact

BAKER BROS. ADVISORS LP filed Form 4 for IGM Biosciences, Inc. (IGMS) on 18 Aug 2025.

Key facts

This page summarizes BAKER BROS. ADVISORS LP's Form 4 filing for IGM Biosciences, Inc. (IGMS).
4 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 18 Aug 2025, 17:39.

Change

Previous filing in this sequence was filed on 01 Aug 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (6)

CIK 0001263508 Primary reporting owner

BAKER BROS. ADVISORS LP

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: By: Baker Bros. Advisors LP, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date: 18 Aug 2025

CIK 0001551139

667, L.P.

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to 667, L.P., pursuant to authority granted by Baker Biotech Capital, L.P., GP to 667, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date: 18 Aug 2025

CIK 0001363364

Baker Brothers Life Sciences LP

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: /s/ Felix J. Baker
Signature date: 18 Aug 2025

CIK 0001087940

BAKER FELIX

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: /s/ Julian C. Baker
Signature date: 18 Aug 2025

CIK 0001087939

BAKER JULIAN

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: By: Baker Bros. Advisors (GP) LLC, Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing
Signature date: 18 Aug 2025

CIK 0001580575

Baker Bros. Advisors (GP) LLC

Relationship: Former 10% owner and director
Address: 860 WASHINGTON STREET, 3RD FLOOR, NEW YORK
Signature: Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to BAKER BROTHERS LIFE SCIENCES, L.P., pursuant to authority granted by Baker Brothers Life Sciences Capital, L.P., GP to Baker Brothers Life Sciences, L.P., /s/ Name: Scott L. Lessing, Title: President
Signature date: 18 Aug 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

IGMS transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -357,048
Change %: -100%
Price
Shares after: 0
Date: 14 Aug 2025
Ownership: See Footnotes
Footnotes: F1, F2, F3, F4, F5, F6, F7

IGMS transaction

Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value
Shares: -3,763,362
Change %: -100%
Price
Shares after: 0
Date: 14 Aug 2025
Ownership: See Footnotes
Footnotes: F1, F3, F4, F5, F6, F7, F8

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

IGMS transaction Derivative

Non-Voting Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value: $0
Shares: -834,707
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 14 Aug 2025
Ownership: See Footnotes
Underlying class: Common Stock
Underlying amount: 834,707
Exercise price
Footnotes: F1, F2, F3, F4, F9

IGMS transaction Derivative

Non-Voting Common Stock

Disposition pursuant to a tender of shares in a change of control transaction

Transaction value: $0
Shares: -9,886,217
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 14 Aug 2025
Ownership: See Footnotes
Underlying class: Common Stock
Underlying amount: 9,886,217
Exercise price
Footnotes: F1, F3, F4, F8, F9

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Section 16 status

BAKER BROS. ADVISORS LP is no longer subject to Section 16 filing requirements. Form 4 or Form 5 obligations may still apply in specific circumstances.

Explanation of responses 9 footnotes

Footnote F1

Reflects the completion of a tender offer by Concentra Biosciences, LLC (the "Parent"), to purchase all of the issued and outstanding shares of voting and non-voting common stock ("Shares") of the IGM Biosciences, Inc. (the "Issuer") for (i) $1.247 per Share in cash plus (ii) one non-transferable contractual contingent value right for each Share in connection with the consummation of the transactions (the "Merger") contemplated by the Agreement and Plan of Merger, dated as of July 1, 2025, by and among the Issuer, 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, Merger Sub merged with and into the Issuer, with the Issuer surviving as a subsidiary of Parent.

Footnote F2

As a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667"), Julian C. Baker and Felix J. Baker each may have been deemed to have had an indirect pecuniary interest in common stock of the Issuer ("Common Stock") reported as disposed in Table I and securities reported as disposed in Table II that were held directly by or that were held for the benefit of 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

Footnote F3

Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667 and Baker Brothers Life Sciences, L.P. ("Life Sciences", and togeher with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held directly by the Funds or for the benefit of the Funds. The Adviser GP is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of the Funds.

Footnote F4

Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds or for the benefit of the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is or was a beneficial owner of such securities for purposes of Section 16 or any other purpose.

Footnote F5

Includes the disposal of 12,098 shares of Common Stock previously issued to Felix J. Baker pursuant to the Issuer's Outside Director Compensation Policy (the "Stock Incentive Plan") in lieu of director retainer fees in his previous capacity as a director of the Issuer and 892 shares of Common Stock previously issued to Dr. Kelvin Neu, a former employee of the Adviser, pursuant to the Stock Incentive Plan in lieu of director retainer fees, and 11,210 shares of Common Stock received previously from the exercise of 11,210 non-qualified options exercisable solely into Common Stock ("Stock Options") that were issued to Dr. Neu in his previous capacity as a director of the Issuer, of which the Funds were deemed to own a portion.

Footnote F6

Pursuant to the policies of the Adviser, Felix J. Baker does not have any right to any of the Issuer's securities issued as compensation for his previous service on the board of directors of the Issuer (the "Board") and Dr. Neu, a former employee of the Adviser, does not have any right to any of the Issuer's securities issued as compensation for his previous service on the Board and the Funds were entitled to an indirect proportionate pecuniary interest in the Stock Options and restricted stock units (each an "RSU"). Solely as a result of their ownership interest in (i) the general partners of the Funds and (ii) the Funds, Felix J. Baker and Julian C. Baker may have been deemed to have had an indirect pecuniary interest in the Stock Options, RSUs and any Common Stock acquired upon the exercise of Stock Options or vesting of RSUs (i.e. no direct pecuniary interest).

Footnote F7

Pursuant to the policies of the Adviser, the Adviser has voting and dispositive power over the Common Stock received in lieu of director retainer fees, Stock Options, RSUs and any Common Stock received as a result of the exercise of Stock Options.

Footnote F8

As a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Julian C. Baker and Felix J. Baker each may have been deemed to have had an indirect pecuniary interest in Common Stock reported as disposed in Table I and securities reported as disposed in Table II that were held directly by or that were held for the benefit of Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

Footnote F9

Represents non-voting common stock of the Issuer ("Non-Voting Common Stock") with no expiration date that was convetible at any time at the option of the holder on a 1-for-1 basis without consideration into Common Stock to the extent that after giving effect to such conversion, the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would have beneficially owned, for purposes of Rule 13d-3 under the Securities Act of 1934, as amended, no more than 4.99% of the outstanding shares of Common Stock (the "Beneficial Ownership Limitation") following such conversion. By written notice to the Issuer, the Funds may have from time to time been able to increase or decrease the Beneficial Ownership Limitation applicable to that Fund to any other percentage not in excess of 19.99%. Any such change would not have been effective until the 61st day after such notice is delivered to the Issuer.

SEC remarks

Felix J. Baker, a managing member of Baker Bros. Advisors (GP) LLC, the sole general partner of Baker Bros. Advisors LP, resigned as a director of IGM Biosciences, Inc. (the "Issuer") immediatley prior to the closing of the merger with Concentra Biosciences, LLC. For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the reporting persons other than Felix J. Baker are no longer deemed directors by deputization of the Issuer.