HCM II Acquisition Corp. — Director's Dealing 2025

Oct 31, 2025

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Terrestrial Energy Inc. /DE/ (IMSR)
CIK: 0002019804
Period of Report: 2025-10-28

Reporting Person: Matthews Shawn (Director)
Reporting Person: HCM Investor Holdings II, LLC (Former 10% owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2025-10-28	Common Stock, par value $0.0001 per share	J	5675000	—	Acquired	5675000	Indirect
2025-10-28	Common Stock, par value $0.0001 per share	J	533514	—	Acquired	533514	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2025-10-28	Warrants	$11.50	J	4275000	Disposed	2030-10-28	Common Stock, par value $0.0001 per share (4275000)	Indirect
2025-10-28	Warrants	$11.50	J	1267599	Disposed	2030-10-28	Common Stock, par value $0.0001 per share (1267599)	Indirect

Footnotes

F1: 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.

F2: 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.

F3: 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.

F4: 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.