[Form 4] IGM Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

IGM Biosciences director Elizabeth H.Z. Thompson reported a disposition of 7,196 shares of the company’s common stock on 08/14/2025 in connection with the completion of a merger. Under the Merger, each outstanding share of IGM common stock was cancelled and converted into the right to receive $1.247 in cash plus one contractual contingent value right (CVR) governed by a Contingent Value Rights Agreement. Following the reported transaction the reporting person beneficially owned 0 shares of common stock.

The filing is a Form 4 disclosure of insider changes tied directly to the Merger transaction and shows the insider’s equity position was eliminated as part of the deal consideration.

Positive

• Merger consideration specified: each share converted into $1.247 cash plus one CVR, providing clear exit terms for holders
• Insider reporting completed: Form 4 discloses the disposition and resulting 0 shares beneficial ownership, maintaining regulatory transparency

Negative

• Director no longer holds common stock following the conversion, eliminating direct insider equity stake
• Form 4 contains no details on CVR economics (payment triggers, caps, or timelines) limiting investor visibility into contingent value

Insights

Corporate Governance Expert

TL;DR: Director’s holdings were fully converted under merger consideration, eliminating direct common-stock ownership.

The Form 4 documents a non-derivative disposition of 7,196 shares by a director on the Merger closing date. The filing clarifies that outstanding shares were cancelled and converted into specified consideration ($1.247 cash plus a CVR), which is a standard post-closing outcome for equity holders. For governance review, the key fact is the director no longer holds common stock post-closing, which may affect future insider reporting obligations and any director alignment with public shareholders.

M&A Specialist

TL;DR: The Form 4 records the operational mechanics of the merger consideration paid to equity holders.

This disclosure confirms the Merger consideration per the Agreement and Plan of Merger: each share converted into $1.247 cash plus a contractual CVR. The transaction date aligns with the Merger closing on 08/14/2025. The filing provides explicit confirmation of share cancellation and conversion terms but does not disclose CVR economic specifics beyond its existence or quantify total deal value for the company or holders.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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X

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Thompson Elizabeth H.Z.

(Last) (First) (Middle)

C/O IGM BIOSCIENCES, INC.

325 E. MIDDLEFIELD ROAD

(Street)

MOUNTAIN VIEW CA 94043

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
IGM Biosciences, Inc. [ IGMS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/14/2025		D		7,196(1)	D	(1)	0	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Pursuant to the Agreement and Plan of Merger dated July 1, 2025, by and among IGM Biosciences, Inc. (the "Company"), Concentra Biosciences, LLC, a Delaware limited liability company ("Parent"), and Concentra Merger Sub V, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), on August 14, 2025, Merger Sub merged with and into the Company (the "Merger"), with the Company continuing as the surviving corporation and a wholly owned subsidiary of Parent. In connection with the Merger, each issued and outstanding share of the Company's Common Stock was cancelled and converted into the right to receive (i) an amount equal to $1.247 in cash and (ii) one contractual contingent value right (a "CVR") subject to the terms and conditions of a Contingent Value Rights Agreement.

	/s/ Elizabath H.Z. Thompson	08/14/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What did the Form 4 filed for IGMS report?

The Form 4 reports a disposition of 7,196 common shares by director Elizabeth H.Z. Thompson on 08/14/2025 tied to the company’s Merger closing.

How were IGM Biosciences (IGMS) shares settled in the Merger?

Each outstanding IGM common share was cancelled and converted into $1.247 in cash plus one contractual contingent value right (CVR) under the Contingent Value Rights Agreement.

How many IGMS shares does the reporting person own after the transaction?

Following the reported transaction the reporting person beneficially owned 0 shares of IGM common stock.

When did the reported transaction for IGMS occur?

The transaction date reported on the Form 4 is 08/14/2025, the Merger closing date.

Does the Form 4 disclose details of the CVR payment terms for IGMS?

No. The Form 4 states a CVR will be issued but does not provide economic details or payment triggers for the CVR.