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

Rhea-AI Filing Summary

IGM Biosciences insider Form 4: Director William Strohl reported a disposition of 125,000 shares of IGM Biosciences common stock on 08/14/2025, leaving him with 0 shares following the transaction. The filing explains this disposal resulted from a merger in which Concentra Merger Sub V, Inc. merged into IGM Biosciences and the company became a wholly owned subsidiary of Concentra Biosciences, LLC. Each outstanding share of common stock was cancelled and converted into the right to receive $1.247 in cash and one contingent value right (CVR) under a Contingent Value Rights Agreement.

Positive

• Merger completed, converting public equity into a defined cash payment of $1.247 per share
• Contingent value right (CVR) provided to former shareholders, preserving potential additional upside tied to defined conditions

Negative

• Director ownership extinguished: reporting person holds 0 shares after the transaction
• Public equity cancelled, removing free-floating shares and replacing them with contractual claims (cash and CVR)

Insights

M&A Specialist

TL;DR: Completion of a definitive merger converted equity into cash plus CVRs, resulting in director dispositions and full corporate control transfer.

The Form 4 confirms closing mechanics of a negotiated acquisition: stockholder equity was cancelled and converted into a fixed cash payment of $1.247 per share plus a CVR, which can preserve contingent upside for former shareholders. The reported 125,000-share disposition by a director reflects the statutorily required disclosure of merger consideration rather than an open-market sale. For investors, the transaction is material because it consummates change of control and replaces public equity with contractual claims (cash and CVR).

Corporate Governance Expert

TL;DR: Director ownership was extinguished by the merger; disclosure complies with Section 16 reporting for insider dispositions tied to a corporate transaction.

The filing shows the reporting person was a director and that the insider's shares were cancelled in connection with the merger consideration, leaving zero direct holdings post-transaction. This is a routine but material governance disclosure following a change in control: it documents the method of consideration and the director's relinquishment of equity. The presence of CVRs indicates contingent post-close entitlements which may require further disclosure on timing and payout conditions elsewhere.

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^*

Strohl William

(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		125,000(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/ William Strohl	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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did William Strohl report on Form 4 for IGMS?

He reported a disposition of 125,000 shares on 08/14/2025, leaving him with 0 shares following the transaction.

Why were the IGMS shares disposed of on 08/14/2025?

The shares were cancelled in connection with a merger; each share was converted into $1.247 cash and one CVR under the Contingent Value Rights Agreement.

What consideration did IGMS shareholders receive in the merger?

Each cancelled IGM Biosciences common share was converted into $1.247 in cash plus one contingent value right (CVR).

Does the Form 4 indicate continued insider ownership after the merger?

No; the filing shows the reporting person held 0 shares following the reported transaction.

Is the Form 4 disposition an open-market sale?

No; the filing explains the disposition resulted from the merger consideration converting outstanding shares into cash and CVRs.