IMSR insider update: equity from Business Combination, $11.5 warrants

Rhea-AI Filing Summary

Terrestrial Energy Inc. (IMSR): Insider ownership update tied to business combination. On 10/28/2025, reporting persons reflected equity received in exchange for prior holdings at the closing of the Business Combination. They reported 5,675,000 shares of common stock beneficially owned indirectly via the Sponsor and 533,514 shares owned directly.

They also reported warrants with a $11.5 exercise price: one block for 4,275,000 underlying shares (indirect via the Sponsor) and another for 1,267,599 underlying shares (indirect via Hondo Holdings LLC). These warrants are first exercisable on 11/27/2025 and expire on 10/28/2030. The filing notes Mr. Shawn Matthews’ control over the Sponsor and Hondo Holdings LLC and his resignation as an officer at 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

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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^*

Matthews Shawn

(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)

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

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)

	Form filed by One Reporting Person
X	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		5,675,000	A	(1)	5,675,000	I	See Footnote(2)
Common Stock, par value $0.0001 per share	10/28/2025		J		533,514	A	(3)	533,514	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
Warrants	$11.5	10/28/2025		J			4,275,000	11/27/2025	10/28/2030	Common Stock, par value $0.0001 per share	4,275,000	$11.5	4,275,000	I	See Footnote(2)
Warrants	$11.5	10/28/2025		J			1,267,599	11/27/2025	10/28/2030	Common Stock, par value $0.0001 per share	1,267,599	$11.5	1,267,599	I	See Footnote(4)

1. Name and Address of Reporting Person^*

Matthews Shawn

(Last) (First) (Middle)

C/O HCM INVESTOR HOLDINGS II, LLC

100 FIRST STAMFORD PLACE, SUITE 330

(Street)

STAMFORD CT 06902

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

HCM Investor Holdings II, LLC

(Last) (First) (Middle)

C/O HCM INVESTOR HOLDINGS II, LLC

100 FIRST STAMFORD PLACE, SUITE 330

(Street)

STAMFORD CT 06902

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

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, dated March 26, 2025 and as amended on October 28, 2025, by and among HCM II, Terrestrial and HCM II Merger Sub Inc. (the "BCA"). The reporting person resigned as an officer of HCM II upon the closing of the Business Combination.

2. Mr. Matthews is the sole managing member of HCM Investor Holdings II, LLC (the "Sponsor"), which is registered owner of these shares and warrants, and Mr. Matthews holds voting and investment power with respect to shares and warrants held of record by the Sponsor.

3. Upon closing of the Business Combination, between Terrestrial Energy Inc., a Delaware corporation formerly known as HCM II Acquisition Corp. ("New Terrestrial"), and Terrestrial Energy Development Inc., a Delaware corporation formerly known as Terrestrial Energy Inc. ("Legacy Terrestrial"), the reporting person acquired these securities in exchange for the reporting person's securities in Legacy Terrestrial pursuant to the terms and conditions of the BCA.

4. Mr. Matthews is the sole managing member of Hondo Holdings LLC, which is registered owner of these warrants, and Mr. Matthews holds voting and investment power with respect to warrants held of record by Hondo Holdings LLC.

	/s/ Shawn Matthews, by Steven Bishcoff, Attorney-in-Fact	10/30/2025
	/s/ HCM Investor Holdings II, LLC, by Steven Bischoff, 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).
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FAQ

What did the Form 4 report for Terrestrial Energy (IMSR)?

It reported equity received at the Business Combination closing, including 5,675,000 indirect shares, 533,514 direct shares, and warrants at $11.5.

How many shares are tied to the reported warrants for IMSR?

Two blocks of warrants were reported: 4,275,000 underlying shares (indirect via the Sponsor) and 1,267,599 underlying shares (indirect via Hondo Holdings LLC).

When are the IMSR warrants exercisable and when do they expire?

They are exercisable on 11/27/2025 and expire on 10/28/2030.

What was the transaction code and date on the Form 4?

Code J (other acquisition) on 10/28/2025, reflecting the exchange in the Business Combination.

Who holds indirect voting and investment power over the reported IMSR securities?

Shawn Matthews, as sole managing member of the Sponsor and of Hondo Holdings LLC, holds voting and investment power over those positions.

What roles were disclosed for the reporting person relative to IMSR?

The filing indicates Director status and notes a resignation as an officer upon the Business Combination closing.