X0508 4 2026-03-12 0001816431 Quantum-Si Inc QSI 0001557736 Keyes Jeffry R. C/O QUANTUM-SI INCORPORATED 29 BUSINESS PARK DRIVE BRANFORD CT 06405 true Chief Financial Officer false Class A Common Stock 2026-03-12 4 A 0 652803 0 A 1816000 D Stock Option (Right to Buy) 0.976 2026-03-12 4 A 0 780847 0 A 2036-03-12 Class A Common Stock 780847 780847 D The grant consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting. The RSUs shall vest in four equal annual installments beginning on April 20, 2027 until fully vested, subject to continued service through the applicable vesting date. The shares underlying this option shall vest in equal quarterly installments beginning on June 20, 2026 until fully vested, subject to continued service through the applicable vesting dates. /s/ Christian LaPointe, Ph.D., Attorney-in-Fact. 2026-03-16