X0609 4 2026-07-23 0 0001918102 DEEP FISSION, INC. FISN 0001192319 GLANVILLE THOMAS S false C/O DEEP FISSION, INC. 2001 ADDISON ST., SUITE 300 BERKELEY CA 94704 1 0 0 0 0 Restricted Stock Unit 0 2026-07-23 4 A 0 19156 0 A Common Stock 19156 19156 D Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock upon vesting. The units vest on July 20, 2027, provided the holder continues to provide service through the vesting date. /s/ Jon Gordon, as Attorney-in-Fact for Thomas S. Glanville 2026-07-27