SCHEDULE: Baker Bros. Exits IGM Biosciences Post-Merger

Baker Bros. Advisors LP and affiliates report full disposition of IGM Biosciences shares following the company's merger with Concentra Biosciences.

Summary

• Baker Bros. Advisors LP, Baker Bros. Advisors (GP) LLC, Julian C. Baker, and Felix J. Baker (the "Reporting Persons") filed Amendment No. 8 to Schedule 13D.
• The amendment reports the disposition of all their holdings in IGM Biosciences, Inc. (the "Issuer") due to the merger with Concentra Biosciences, LLC.
• The merger, contemplated by an agreement dated July 1, 2025, became effective on August 14, 2025.
• Under the merger terms, a tender offer was completed where each share of Common Stock and Non-Voting Common Stock was exchanged for $1.247 in cash plus one non-transferable contractual contingent value right (CVR).
• Prefunded Warrants were converted into the right to receive the Merger Consideration, net of exercise cost.
• All previously reported Stock Options were cancelled by the Issuer for no value.
• The Reporting Persons, through their funds 667, L.P. and Baker Brothers Life Sciences, L.P., disposed of 4,072,010 shares of Common Stock, 10,720,924 shares of Non-Voting Common Stock, and 666,666 Prefunded Warrants.
• Felix J. Baker also disposed of 12,098 shares of Common Stock directly held for the benefit of the Funds, which included 953 restricted stock units (RSUs) granted on June 30, 2025, and accelerated by the merger.
• The Adviser disposed of 12,102 shares of Common Stock directly held for the benefit of the Funds.
• As of August 14, 2025, the Reporting Persons ceased to beneficially own any securities of IGM Biosciences, Inc., including no longer owning more than five percent of the Common Stock.

Sentiment

Score: 5

Explanation: The filing is purely factual, reporting the completion of a merger and the subsequent disposition of shares by a major holder. It contains no subjective language or forward-looking statements that would indicate a positive or negative sentiment beyond the factual reporting of the transaction.

Negatives

• Stock Options held by the Reporting Persons were cancelled for no value received as part of the merger.

Future Outlook

The filing reports a completed transaction and the cessation of beneficial ownership by the Reporting Persons; it does not provide forward-looking statements or guidance for IGM Biosciences, Inc. or the Reporting Persons' future investment strategies.

Industry Context

This filing reflects the completion of a corporate acquisition within the biotechnology sector, where a publicly traded company (IGM Biosciences) was acquired by a private entity (Concentra Biosciences). Such transactions are common in the biotech industry, often driven by strategic portfolio consolidation or the acquisition of specific therapeutic assets.

Management Changes

Stakeholder Impact

• Shareholders of IGM Biosciences, Inc. received $1.247 in cash and one CVR per share as part of the merger consideration.
• Holders of Prefunded Warrants received merger consideration net of exercise cost.
• Holders of Stock Options had their options cancelled for no value.

Key Dates

Keywords

IGM Biosciences, Concentra Biosciences, Merger, Schedule 13D/A, Baker Bros. Advisors, Tender Offer, Common Stock, Non-Voting Common Stock, Prefunded Warrants, Contingent Value Right, Biotechnology, Pharmaceuticals