Form 4 Filing for Brian Patrick Thrasher

This filing details transactions made by Brian Patrick Thrasher, Chief Financial Officer of Terrestrial Energy Inc. /DE/, on April 12, 2026. Thrasher acquired 49,917 Restricted Stock Units (RSUs) and 58,236 Stock Options. The RSUs, granted under the 2025 Equity Incentive Plan, vest in three increments over three years, contingent on continued service. Each RSU represents a contingent right to one share of Common Stock. The stock options, also granted under the 2025 Equity Incentive Plan, have a vesting schedule similar to the RSUs and an exercise price of $6.34. These transactions are reported on Form 4, indicating they are not subject to Section 16 of the Securities Exchange Act of 1934.