Terrestrial Energy director Form 3 lists 268,220 stock options

Rhea-AI Filing Summary

Terrestrial Energy Inc. (IMSR) disclosed an initial statement of beneficial ownership (Form 3) by a director. The filing reports 6,669 shares of Common Stock held directly and 14,930 shares held indirectly through a trust.

Derivative holdings include stock options for 22,352 shares exercisable at $1.4764 (price in Canadian dollars) expiring 10/01/2036, 111,758 shares at $2.0133 expiring 11/19/2037, and options for 67,055 shares at $2.237 expiring 04/01/2043 (vesting in thirds annually from 04/01/2024) and 67,055 shares at $2.237 expiring 02/03/2045 (vesting in thirds from 02/03/2026). Warrants cover 22,352 shares (direct) and 44,703 shares (through a trust) at $2.237 expiring 07/31/2028. Contingent value rights may deliver additional shares if the 20‑day VWAP after the lock‑up is less than 75% of the $7.905 redemption price.

The equity positions were received in connection with the closing of the business combination between New Terrestrial and Legacy Terrestrial.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

BUCKMAN FREDERICK W

(Last) (First) (Middle)

2730 W. TYVOLA ROAD, SUITE 100

(Street)

CHARLOTTE NC 28217

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
10/28/2025

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

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

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock, par value $0.0001 per share ("Common Stock")	6,669(1)	D
Common Stock	14,930(1)	I	Through Trust

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	(2)	10/01/2036	Common Stock	22,352	$1.4764(6)	D
Stock Option (Right to Buy)	(2)	11/19/2037	Common Stock	111,758	$2.0133	D
Stock Option (Right to Buy)	04/01/2024(3)	04/01/2043	Common Stock	67,055	$2.237	D
Stock Option (Right to Buy)	02/03/2026(3)	02/03/2045	Common Stock	67,055	$2.237	D
Warrants (Right to Buy)	(4)	07/31/2028	Common Stock	22,352	$2.237	D
Warrants (Right to Buy)	(4)	07/31/2028	Common Stock	44,703	$2.237	I	Through Trust
Contingent Value Right	(5)	(5)	Common Stock	(5)	(5)	D
Contingent Value Right	(5)	(5)	Common Stock	(5)	(5)	I	Through Trust

Explanation of Responses:

1. 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 person 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.

2. Consists of options granted pursuant to the Legacy Terrestrial Second Amended and Restated 2024 Stock Option Plan. The options are currently exercisable.

3. Consists of options granted pursuant to the Legacy Terrestrial Second Amended and Restated 2024 Stock Option Plan. The options vest in one-third increments on each of the first, second and third anniversaries of the grant date, subject to the reporting person's continued service through each applicable vesting date.

4. Consists of Legacy Terrestrial warrants to purchase common stock that are currently exercisable.

5. Consists of contingent value right issued upon conversion of Legacy Terrestrial convertible notes in connection with the Business Combination. Each contingent value right entitles the holder to receive additional shares of Common Stock in the event that the volume weighed average price of the Common Stock for the twenty (20) trading days beginning on the trading day immediately following expiration of the lock-up period contemplated by the applicable Legacy Terrestrial convertible note is less than seventy-five percent (75%) of the redemption price ($7.905).

6. Price is expressed in Canadian dollars.

Remarks:

Exhibit List - Exhibit 24.1 - Power of Attorney

	/s/ Steven M. Millsap, pursuant to Power of Attorney	11/07/2025
	** 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 5 (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 Terrestrial Energy (IMSR) disclose in this Form 3?

A director reported initial beneficial ownership, including 6,669 shares directly and 14,930 shares indirectly through a trust, plus options, warrants, and contingent value rights.

How many non-derivative common shares were reported?

The filing lists 6,669 shares held directly and 14,930 held indirectly via a trust.

What derivative securities and amounts are included?

Stock options for 22,352, 111,758, 67,055, and 67,055 shares; warrants for 22,352 (direct) and 44,703 (through a trust) shares.

What are the option exercise prices and expirations?

Options are at $1.4764 (CAD) expiring 10/01/2036, $2.0133 expiring 11/19/2037, and $2.237 expiring 04/01/2043 and 02/03/2045.

How do the vesting schedules work for certain options?

Options dated 04/01/2024 and 02/03/2026 vest in one‑third increments on each of the first, second, and third anniversaries of the grant date.

What are the terms of the reported warrants?

Warrants cover 22,352 shares (direct) and 44,703 shares (through a trust) at $2.237, expiring 07/31/2028.

What triggers the contingent value rights (CVRs)?

Each CVR entitles the holder to additional shares if the 20‑day VWAP after the lock‑up is below 75% of the $7.905 redemption price.