Roberto Marco Sella - 29 Oct 2025 Form 3 Insider Report for Terrestrial Energy Inc. /DE/ (IMSR)

Role: 10%+ Owner
Signature: /s/ Grant Levine, attorney-in-fact
Issuer symbol: IMSR
Transactions as of: 29 Oct 2025
Net transactions value: $0
Form type: 3
Filing time: 22 Jan 2026, 17:15:12 UTC
Previous filing: 02 Oct 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Sella Roberto Marco	10%+ Owner	C/O LL FUNDS, LLC, 2400 MARKET STREET, PHILADELPHIA	/s/ Grant Levine, attorney-in-fact	22 Jan 2026	0001770593

This filing has been restated, see here for the amended filing

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	IMSR	Common Stock						180,316	29 Oct 2025	Direct	F1
holding	IMSR	Common Stock						12,244,088	29 Oct 2025	See footnote	F1, F2
holding	IMSR	Common Stock						807,873	29 Oct 2025	See footnote	F1, F3
holding	IMSR	Common Stock						653,334	29 Oct 2025	See footnote	F1, F4

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	IMSR	Warrants to purchase shares of Common Stock							29 Oct 2025	Common Stock	539,117	$2.24	Direct	F1
holding	IMSR	Warrants to purchase shares of Common Stock							29 Oct 2025	Common Stock	223,515	$2.24	See footnote	F1, F3
holding	IMSR	Warrants to purchase shares of Common Stock							29 Oct 2025	Common Stock	59,902	$2.24	See footnote	F1, F4
holding	IMSR	Warrants to purchase shares of Common Stock							29 Oct 2025	Common Stock	670,544	$2.24	See footnote	F1, F4

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Upon closing of the business combination (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 persons acquired these securities in exchange for the reporting person's securities in Legacy Terrestrial pursuant to the terms and conditions of the Business Combination Agreement, dated as of March 26, 2025, by and among HCM II Acquisition Corp., HCM II Merger Sub Inc. and Legacy Terrestrial.
F2	Represents securities jointly held by the reporting person and the reporting person's spouse. The reporting person disclaims beneficial ownership of the securities held jointly with his spouse except to the extent of his pecuniary interest therein
F3	Represents securities held by Roberto M. Sella 2012 Family Trust (the "Trust"), of which the reporting person is the trustee. The reporting person may be deemed to have voting and dispositive power over the shares held by the Trust. The reporting person disclaims beneficial ownership of the securities held by the Trust except to the extent of his pecuniary interest therein.
F4	Represents securities held by LL Charitable Foundation (the "Foundation"), of which the reporting person is the president. The reporting person may be deemed to have voting and dispositive power over the shares held by the Foundation. The reporting person disclaims beneficial ownership of the securities held by the Foundation except to the extent of his pecuniary interest therein.

Remarks:

Exhibits List 24 - Confirming Statement