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

Rhea-AI Filing Summary

IGM Biosciences insider report: Mary Beth Harler, who serves as both Chief Executive Officer and a director, reported the disposition of 323,680 shares of IGM Biosciences common stock on 08/14/2025. Following the reported transaction, Harler beneficially owned 0 shares. The filing explains these shares (including previously reported restricted stock units) were cancelled and converted as part of a merger transaction: each outstanding share and RSU was converted into $1.247 in cash plus one contractual contingent value right under a Contingent Value Rights Agreement. The Form 4 indicates the change in beneficial ownership resulted from the merger consummated on that date.

Positive

• The merger converted each outstanding share and RSU into $1.247 in cash plus one contractual contingent value right, providing immediate cash consideration.
• The Form 4 clearly ties the disposition to the Agreement and Plan of Merger and the merger closing on 08/14/2025, documenting transactional mechanics.

Negative

• The reporting person, who is the Chief Executive Officer and a director, now beneficially owns 0 shares following the conversion, eliminating insider common-stock ownership.
• Shareholders' equity positions were cancelled and replaced with cash plus CVRs, which changes the risk/return profile for former common-stock holders.

Insights

Corporate Governance Expert

TL;DR: CEO/director's equity was cancelled in a merger, converted to cash and CVR; insider now holds no common shares.

The Form 4 documents a complete disposition of 323,680 common shares by the reporting person due to a corporate merger that converted all outstanding shares and RSUs into $1.247 cash per share and one contingent value right each. From a governance perspective, this is a routine post-closing ownership change tied to a change-of-control transaction rather than an open-market sale. The filing confirms alignment between the merger consideration and the mechanics for equity settlement, but it also means the company's listed insiders no longer hold common stock post-merger.

Mergers & Acquisitions Specialist

TL;DR: Merger closed on 08/14/2025; equity converted to cash plus CVRs, driving the reported disposition.

The disclosure ties the reported disposition directly to the Agreement and Plan of Merger dated July 1, 2025, and the closing on August 14, 2025. The conversion terms—$1.247 cash per share plus one CVR—are explicitly stated, indicating a cash-out transaction with contingent future upside preserved via CVRs. This is a material corporate event for shareholders because it replaces equity with a fixed cash component and a contractual contingent value right, altering the risk/return profile for former equity 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

OMB APPROVAL

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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^*

Harler Mary Beth

(Last) (First) (Middle)

C/O IGM BIOSCIENCES, INC.

3 EAST THIRD AVENUE, SUITE 200

(Street)

SAN MATEO CA 94401

(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
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

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		323,680(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. Certain of these shares are represented by previously reported restricted stock units ("RSUs"). 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, and each outstanding RSU, 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/ Mary Beth Harler	08/14/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What did Mary Beth Harler report on Form 4 for IGMS?

The Form 4 reports a disposition of 323,680 shares on 08/14/2025, after which she beneficially owned 0 shares.

Why were the shares disposed according to the filing?

The filing states the shares and previously reported RSUs were cancelled and converted in connection with a merger consummated on 08/14/2025.

What consideration did former shareholders receive in the merger?

Each issued and outstanding share and each RSU was converted into $1.247 in cash and one contingent value right (CVR) under a Contingent Value Rights Agreement.

Does the Form 4 indicate any open-market sale by the insider?

No. The Form 4 attributes the disposition to the merger conversion mechanics, not an open-market sale.

When was the Agreement and Plan of Merger dated?

The filing references an Agreement and Plan of Merger dated July 1, 2025.