(IMSR)

Reporting relationship: Chief Executive Officer, Director
Issuer ticker: IMSR
Reported as of: 28 Oct 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 30 Oct 2026, 09:17:50 UTC
Prior SEC filing: 26 Oct 2026
Source filing: View source filing
Reporting owner signature: /s/ Brian Thrasher, as Attorney-in-Fact

Filing notes and source

Key filing fact

Simon Irish filed Form 4 for Terrestrial Energy Inc. /DE/ (IMSR) on 30 Oct 2026.

Key facts

This page summarizes Simon Irish's Form 4 filing for Terrestrial Energy Inc. /DE/ (IMSR).
2 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 30 Oct 2026, 09:17.

Change

Previous filing in this sequence was filed on 26 Oct 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002091865 Primary reporting owner

Irish Simon

Relationship: Chief Executive Officer, Director
Address: C/O TERRESTRIAL ENERGY INC., 2730 W. TYVOLA ROAD, SUITE 100, CHARLOTTE
Signature: /s/ Brian Thrasher, as Attorney-in-Fact
Signature date: 30 Oct 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

IMSR transaction

Common Stock

Options Exercise

Transaction value
Shares: +55,432
Change %: +2%
Price: $0.000000^*
Shares after: 2,879,846
Date: 28 Oct 2026
Ownership: Direct
Footnotes: F1

IMSR holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 2,818,520
Date: 28 Oct 2026
Ownership: Through LLC

IMSR holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 52,255
Date: 28 Oct 2026
Ownership: Through IRA

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

IMSR transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value
Shares: -55,432
Change %: -33%
Price: $0.000000^*
Shares after: 110,866
Date: 28 Oct 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 55,432
Exercise price
Footnotes: F2, F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 3 footnotes

Footnote F1

Represents shares of common stock subject to vested portion of restricted stock unit award.

Footnote F2

Each restricted stock unit represents a contingent right to receive one share of common stock.

Footnote F3

The restricted stock units vest pro rata over a three year period following the grant date, subject to Mr. Irish's continued employment through each applicable vesting date and accelerated vesting in certain events.