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.

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.

The Reporting Persons no longer beneficially own any securities of the Issuer.

(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) 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) 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.