X0508 4 2024-03-22 0001816431 Quantum-Si Inc QSI 0002016312 Dowdy Paula C/O QUANTUM-SI INCORPORATED 29 BUSINESS PARK DRIVE BRANFORD CT 06405 true false Class A Common Stock 2024-03-22 4 A 0 159217 0 A 159217 D Consists of restricted stock units ("RSUs"). Each RSU represents the right to receive one share of common stock upon vesting. The RSUs vest in annual installments over three years beginning on March 22, 2025, subject to Ms. Dowdy's continued service through the applicable vesting date. /s/ Christian LaPointe, Ph.D., Attorney-in-Fact 2024-03-25