Quantum-Si Inc

Rule 10b5-1 Trading Arrangements

Effective August 26, 2026, Dr. Jonathan Rothberg, who is amember of the Board, acting on his own behalf and on behalf of entities owned by trusts created for the benefit of his children, entered into a 10b5-1 sales plan (the “Sales Plan”) intended to satisfy the affirmative defense of Rule 10b5-1(c) under the Exchange Act. The Sales Plan provides for the sale of up to 8,947,746 shares of the Company’s Class A common stock beginning on January 15, 2027 and shall terminate upon the earliest of (i)January 15, 2028, (ii) the sale of 8,947,746 shares of the Company’s Class A common stock, or (iii) the occurrence of any of the other terminating events set forth in the Sales Plan.

Other than as disclosed above, during the quarter ended September 30, 2026, no other officers or directors, as defined in Rule 16a-1(f), adopted, modified orterminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as defined in Item 408 of Regulation S-K.

Lease Termination

On October 30, 2026, Quantum-Si Incorporated (the“Company”) entered into a Mutual Lease Termination and Settlement Agreement (the“Termination Agreement”) with Sterling City Science South Development, LLC (the“Landlord”). Under the Termination Agreement, the parties mutually terminated, effective that date, the lease agreement dated June 18, 2026 (the“Lease Agreement”) for approximately 54,374 rentable square feet of planned office, laboratory and manufacturing space at 9955 Pacific Heights Boulevard, San Diego, California. The Lease Agreement was previously described in the Company’s Current Report on Form 8-K filed on June 24, 2026. It provided for a ten-year term, aggregate minimum cash lease payments of approximately $38.3 million and a tenant improvement allowance of up to approximately $17.1 million. The lease term had not commenced, and, subject to the effectiveness of the mutual releases described below, the Company has no further obligations under the Lease Agreement.

Under the Termination Agreement, the Landlord is required to pay the Company approximately $1.3 million. This consists of approximately $0.7 million in reimbursement of tenant improvement costs incurred by the Company, approximately $0.4 million as a refund, with interest, of the security deposit paid upon execution of the Lease Agreement, and approximately $0.2 million in reimbursement of legal fees and letter of credit fees. The Landlord is also required to cause the return, for cancellation, of the Company’s approximately $2.1 million letter of credit that secured its obligations under the Lease Agreement. The parties exchanged mutual releases of claims relating to the Lease Agreement; the Company’s release becomes effective upon its receipt of the payment. The Company did not incur any early termination penalties. Other than the Lease Agreement, there is no material relationship between the Company or its affiliates and the Landlord.