Terrestrial Energy (IMSR) director amends Form 4 on RSUs grant details

Rhea-AI Filing Summary

Terrestrial Energy Inc. filed an amended Form 4 for a director to correct the reported size of a recent equity award. On 12/18/2025, the director received 1,029 restricted stock units, each representing a contingent right to one share of common stock at a price of $0 per unit.

The restricted stock units will vest 100% on December 31, 2026, as long as the director continues to provide service to Terrestrial Energy Inc. After this grant, the director beneficially owns 6,894 derivative securities. The amendment notes that the original Form 4 filed on 12/22/2025 contained an inadvertent error in the number of restricted stock units reported.

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

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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^*

JOHNSON WILLIAM D

(Last) (First) (Middle)

2730 W. TYVOLA ROAD, SUITE 100

(Street)

CHARLOTTE NC 28217

(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)
12/18/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)
12/22/2025

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 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

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
Restricted Stock Units	(1)	12/18/2025		A		1,029(2)		(1)	(1)	Common Stock	1,029	$0	6,894	D

Explanation of Responses:

1. Each restricted stock unit represents a contingent right to acquire one share of Common Stock. So long as the Reporting Person provides continuous service to Terrestrial Energy, Inc., 100% of the restricted stock units will vest on December 31, 2026.

2. On December 22, 2025, the Reporting Person filed a Form 4 in which there was an inadvertent error in the number of reported restricted stock units.

	/s/ Steven M. Millsap, Attorney-in-Fact	01/09/2026
	** 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 insider transaction did Terrestrial Energy (IMSR) report in this amended Form 4?

The filing reports that a director of Terrestrial Energy Inc. received 1,029 restricted stock units on 12/18/2025, each convertible into one share of common stock at a price of $0 per unit.

Why was this Terrestrial Energy (IMSR) Form 4 amended?

The Form 4 was amended because the director’s earlier filing on 12/22/2025 contained an inadvertent error in the number of restricted stock units reported.

What are the vesting terms of the 1,029 restricted stock units at Terrestrial Energy?

The filing states that 100% of the 1,029 restricted stock units will vest on December 31, 2026, provided the director continues to provide service to Terrestrial Energy Inc. through that date.

How many derivative securities does the Terrestrial Energy director own after this RSU grant?

After the reported transaction, the director beneficially owns 6,894 derivative securities, as shown in the derivative securities table.

What does each restricted stock unit in this Terrestrial Energy filing represent?

Each restricted stock unit represents a contingent right to acquire one share of Terrestrial Energy Inc. common stock, according to the explanation of responses.

What is the relationship of the reporting person to Terrestrial Energy Inc.?

The reporting person is identified as a Director of Terrestrial Energy Inc. in the relationship section of the filing.