Insider reports 25,000 IMSR shares after business combination

Rhea-AI Filing Summary

Terrestrial Energy Inc. reported an insider Form 4 showing the acquisition of 25,000 shares of common stock on 10/28/2025. The filing lists transaction code J, and the shares were received in exchange for the reporting person’s Terrestrial securities at the closing of the business combination with the SPAC formerly known as HCM II Acquisition Corp., pursuant to the business combination agreement.

Following the reported transaction, the filing shows beneficial ownership of 25,000 shares, held directly. The explanatory note states the reporting person resigned as a director of HCM II upon the business combination closing.

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

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Brenner Andrew Scott

(Last) (First) (Middle)

C/O HCM INVESTOR HOLDINGS II, LLC

100 FIRST STAMFORD PLACE, SUITE 330

(Street)

STAMFORD CT 06902

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Terrestrial Energy Inc. /DE/ [ IMSR ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
10/28/2025

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, par value $0.0001 per share	10/28/2025		J		25,000	A	(1)	25,000	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. Upon closing of the business combination (the "Business Combination") between the Issuer (which was formerly known as HCM II Acquisition Corp. or "HCM II") and Terrestrial Energy Inc. ("Terrestrial") the reporting person acquired these securities in exchange for the reporting person's securities in Terrestrial pursuant to the terms and conditions of the business combination agreement, by and among HCM, Terrestrial and HCM II Merger Sub Inc. (the "BCA"). The reporting person resigned as a director of HCM II upon the closing of the Business Combination.

	/s/ Andrew Brenner, by Steven Bishcoff, Attorney-in-Fact	10/30/2025
	** 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 Terrestrial Energy Inc. (IMSR) disclose in this Form 4?

An insider acquired 25,000 common shares on 10/28/2025 via transaction code J.

How were the 25,000 IMSR shares acquired?

They were received in an exchange at the closing of the business combination with HCM II Acquisition Corp., per the business combination agreement.

What is the insider’s beneficial ownership after the transaction?

The filing reports 25,000 shares beneficially owned following the transaction.

What does transaction code J indicate in this context?

Code J denotes a transaction type not otherwise specified, here reflecting shares received in exchange at business combination closing.

Is the ownership direct or indirect after the transaction?

The Form 4 indicates direct ownership of the 25,000 shares.

Was there any board change tied to the combination?

Yes. The note states the reporting person resigned as a director of HCM II upon closing.