144 0001690473 XXXXXXXX LIVE 0001816431 Quantum-Si Inc 001-39486 29 BUSINESS PARK DRIVE BRANFORD CT 06405 (203) 458-7100 Bennett Todd C. Officer Class A Common Stock Morgan Stanley Smith Barney LLC

1 New York Plaza 38th Floor New York NY 10004

36964 61315.88 577927 09/22/2025 NASDAQ Class A Common Stock 09/17/2024 Restricted Stock Unit Vesting Quantum-Si Incorporated N 33534 09/17/2024 Equity compensation for services rendered Class A Common Stock 03/12/2025 Restricted Stock Unit Vesting Quantum-Si Incorporated N 3430 03/12/2025 Equity compensation for services rendered N Morgan Stanley Smith Barney LLC

1 New York Plaza 38th Floor New York NY 10004

Class A Common Stock 09/22/2025 18482 31097.81 Morgan Stanley Smith Barney LLC

1 New York Plaza 38th Floor New York NY 10004

Class A Common Stock 09/23/2025 18482 30218.07 Shares sold to cover tax withholding obligations in connection with the vesting of restricted stock units. The sale is mandated by the Issuers election to require the satisfaction of tax withholding obligations through a sell to cover transaction and does not represent a discretionary trade by the reporting person. 10/20/2025 /s/ Christian LaPointe, Ph.D., Attorney-in-Fact