Terrestrial Energy CEO buys 16,900 shares

Irish's reported positions also include common shares held indirectly through an LLC and an IRA.

Rhea-AI Filing Summary

Terrestrial Energy Inc. (IMSR) Chief Executive Officer and director Simon Irish purchased 16,900 common shares at $3.007 per share on October 13, 2026. His direct holdings after the purchase were 2,312,834 shares. He also reported indirect holdings of 2,818,520 shares through an LLC and 52,255 shares through an IRA. No Rule 10b5-1 plan is reported.

Insider Trade Summary

Net Buyer: 16,900 shares

Net Buy 3 txns

Insider Irish Simon

Role Chief Executive Officer

Bought 16,900 shs ($51K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	16,900	$3.007	$51K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 2,312,834 shares (Direct); Common Stock — 2,818,520 shares (Indirect, Through LLC); Common Stock — 52,255 shares (Indirect, Through IRA)

Key Figures

Common shares purchased: 16,900 shares Price per share: $3.007 per share Direct holdings after purchase: 2,312,834 shares +2 more

5 metrics

Common shares purchased 16,900 shares October 13, 2026

Price per share $3.007 per share Purchase on October 13, 2026

Direct holdings after purchase 2,312,834 shares Simon Irish

Indirect holdings through LLC 2,818,520 shares Simon Irish

Indirect holdings through IRA 52,255 shares Simon Irish

FAQ

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

How many IMSR shares did Simon Irish buy, and at what price?

Simon Irish, Terrestrial Energy Inc.'s CEO and director, purchased 16,900 common shares at $3.007 per share on October 13, 2026. His direct holdings after the purchase were 2,312,834 shares. No Rule 10b5-1 plan is reported.

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

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 10/14/2026 - 09:16 AM EDT Accepted by SEC EDGAR 10/14/2026 - 09:15 AM 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^*

Irish Simon

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
10/13/2026

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
Common Stock	10/13/2026		P		16,900	A	$3.007	2,312,834	D
Common Stock								2,818,520	I	Through LLC
Common Stock								52,255	I	Through IRA

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

Explanation of Responses:

	/s/ Brian Thrasher, as Attorney-in-Fact	10/14/2026
	** 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)