(IMSR)

Reporting relationship: Chief Financial Officer
Issuer ticker: IMSR
Reported as of: 12 Apr 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 14 Apr 2026, 18:00:04 UTC
Prior SEC filing: 07 Nov 2025
Source filing: View source filing
Reporting owner signature: /s/ Steven M. Millsap, Attorney-in-Fact

Key filing fact

Brian Patrick Thrasher filed Form 4 for Terrestrial Energy Inc. /DE/ (IMSR) on 14 Apr 2026.

Key facts

This page summarizes Brian Patrick Thrasher's Form 4 filing for Terrestrial Energy Inc. /DE/ (IMSR).
2 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 14 Apr 2026, 18:00.

Change

Previous filing in this sequence was filed on 07 Nov 2025.
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 0002091861 Primary reporting owner

Thrasher Brian Patrick

Relationship: Chief Financial Officer
Address: C/O TERRESTRIAL ENERGY INC., 2730 W. TYVOLA ROAD, SUITE 100, CHARLOTTE
Signature: /s/ Steven M. Millsap, Attorney-in-Fact
Signature date: 14 Apr 2026

Reported derivative securities

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

IMSR transaction Derivative

Restricted Stock Units

Award

Transaction value
Shares: +49,917
Change %
Price: $0.000000^*
Shares after: 49,917
Date: 12 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 49,917
Exercise price
Footnotes: F1, F2

IMSR transaction Derivative

Stock Option (Right to Buy)

Award

Transaction value
Shares: +58,236
Change %
Price: $0.000000^*
Shares after: 58,236
Date: 12 Apr 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 58,236
Exercise price: $6.34
Footnotes: 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

Each restricted stock unit represents a contingent right to acquire one share of Common Stock.

Footnote F2

Consists of restricted stock units granted pursuant to the Terrestrial Energy Inc. 2025 Equity Incentive Plan. The restricted stock units 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.

Footnote F3

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.