IMSR insider Form 3 lists multiple stock option grants

Rhea-AI Filing Summary

Terrestrial Energy Inc. (IMSR) filed a Form 3 for its Chief Operating Officer, reporting derivative holdings under Section 16.

The filing lists multiple stock options to purchase common stock, including 223,515 options expiring on 05/02/2036 at an exercise price of $1.1185, 335,272 options expiring on 02/06/2037 at $1.4764, and 156,461 options exercisable on 04/01/2024 and expiring on 04/01/2043 at $2.237. The table also includes 134,109 options exercisable on 06/20/2027 and expiring on 06/25/2045 at $7.8295. The filing notes that prices are expressed in Canadian dollars.

Vesting terms vary by grant, including milestone-based vesting, vesting in one-third annual increments over three years, and one-half increments on June 20, 2027 and June 30, 2028.

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^*

Smith William F.

(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)

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

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)

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)	(1)	05/02/2036	Common Stock	223,515	$1.1185(5)	D
Stock Option (Right to Buy)	(1)	02/06/2037	Common Stock	335,272	$1.4764(5)	D
Stock Option (Right to Buy)	(1)	08/01/2038	Common Stock	8,941	$2.0133	D
Stock Option (Right to Buy)	(2)	02/06/2039	Common Stock	447,030	$2.0133	D
Stock Option (Right to Buy)	(1)	01/27/2040	Common Stock	111,758	$2.0133	D
Stock Option (Right to Buy)	(1)	11/18/2040	Common Stock	223,515	$2.237	D
Stock Option (Right to Buy)	(1)	05/19/2042	Common Stock	89,406	$2.237	D
Stock Option (Right to Buy)	04/01/2024(3)	04/01/2043	Common Stock	156,461	$2.237	D
Stock Option (Right to Buy)	06/20/2027(4)	06/25/2045	Common Stock	134,109	$7.8295	D

Explanation of Responses:

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

2. Consists of options granted pursuant to the Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan. The options vest based on certain specified milestone conditions.

3. Consists of options granted pursuant to the Terrestrial Energy Inc. 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 options granted pursuant to the Terrestrial Energy Inc. Second Amended and Restated 2024 Stock Option Plan. The options vest in one-half increments on June 20, 2027 and June 30, 2028.

5. 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).
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) file?

A Form 3 reporting the Chief Operating Officer’s derivative securities (stock options) under Section 16.

Who is the reporting person and their role at IMSR?

The reporting person is the Chief Operating Officer of Terrestrial Energy Inc..

What are key option positions disclosed by IMSR’s COO?

Examples include 223,515 options expiring 05/02/2036 at $1.1185 and 335,272 options expiring 02/06/2037 at $1.4764.

Are the exercise prices in U.S. or Canadian dollars?

The filing states the price is expressed in Canadian dollars.

What vesting schedules are described in the filing?

Vesting includes milestone-based, one-third annually over three years, and one-half on June 20, 2027 and June 30, 2028.

What is the event date on the Form 3?

The date of the event requiring the statement is 10/28/2025.

Does the filing list non-derivative holdings?

The provided excerpt shows details for derivative securities (stock options) in Table II.