Terrestrial Energy grants executive 152,672 options

The options vest over the first three grant anniversaries, subject to continued service through each applicable vesting date.

Rhea-AI Filing Summary

Terrestrial Energy Inc. reported that Chief Commercial Officer David Woodward Williams received a grant of 152,672 stock options to buy common stock on October 19, 2026. The options have a $3.93-per-share exercise price and expire October 19, 2036. They vest in one-third increments on each of the first, second and third anniversaries of the grant date, subject to his continued service through each applicable vesting date.

Insider Trade Summary

Grant/Award: 152,672 shares

Grant/Award 1 txn

Insider Williams David Woodward

Role Chief Commercial Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy) F1	152,672	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 152,672 contracts (Direct)

Footnotes (1)

1. F1. Consists of options granted pursuant to the Terrestrial Energy Inc. 2025 Equity Incentive 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.

Key Figures

Stock options granted: 152,672 options Exercise price: $3.93 per share Vesting schedule: One-third increments +1 more

4 metrics

Stock options granted 152,672 options Grant to Chief Commercial Officer David Woodward Williams on October 19, 2026

Exercise price $3.93 per share Options to buy common stock

Vesting schedule One-third increments On each of the first, second and third anniversaries of the grant date, subject to continued service

Expiration date October 19, 2036 Stock options granted October 19, 2026

Key Terms

2025 Equity Incentive Plan, vest in one-third increments, continued service

3 terms

2025 Equity Incentive Plan financial

"options granted pursuant to the Terrestrial Energy Inc. 2025 Equity Incentive Plan"

vest in one-third increments technical

"vest in one-third increments on each of the first, second and third anniversaries"

continued service financial

"subject to the reporting person's continued service through each applicable vesting date"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many stock options did Terrestrial Energy (IMSR) Chief Commercial Officer David Woodward Williams receive?

David Woodward Williams received a grant of 152,672 options to buy common stock, with an exercise price of $3.93 per share.

When do the IMSR options vest?

The options vest in one-third increments on each of the first, second and third anniversaries of the October 19, 2026 grant date, subject to David Woodward Williams's continued service through each applicable vesting date.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 10/21/2026 - 05:17 PM EDT Accepted by SEC EDGAR 10/21/2026 - 05:17 PM EDT Learn about SEC filing dates

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Williams David Woodward

(Last) (First) (Middle)

C/O TERRESTRIAL ENERGY INC.

2730 W. TYVOLA ROAD, SUITE 100

(Street)

CHARLOTTE NORTH CAROLINA 28217

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/19/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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

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
Stock Option (Right to Buy)	$3.93	10/19/2026		A		152,672		10/19/2027(1)	10/19/2036	Common Stock	152,672	$0	152,672	D

Explanation of Responses:

1. Consists of options granted pursuant to the Terrestrial Energy Inc. 2025 Equity Incentive 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.

	/s/ Brian Thrasher, Attorney-in-Fact	10/21/2026
	** 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).
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.
* Form 4: SEC 1474 (03-26)