X0508 4/A 2025-12-18 2025-12-22 0002019804 Terrestrial Energy Inc. /DE/ IMSR 0001183048 JOHNSON WILLIAM D 2730 W. TYVOLA ROAD, SUITE 100 CHARLOTTE NC 28217 1 0 0 0 0 Restricted Stock Units 2025-12-18 4 A 0 1029 0 A Common Stock 1029 6894 D Each restricted stock unit represents a contingent right to acquire one share of Common Stock. So long as the Reporting Person provides continuous service to Terrestrial Energy, Inc., 100% of the restricted stock units will vest on December 31, 2026. On December 22, 2025, the Reporting Person filed a Form 4 in which there was an inadvertent error in the number of reported restricted stock units. /s/ Steven M. Millsap, Attorney-in-Fact 2026-01-09