Quantum-Si Inc

Report of Independent Registered Public Accounting Firm

To the Board of Directors and Stockholders of Quantum-Si Incorporated

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheet of Quantum-Si Incorporated and its subsidiaries (the“Company”) as of December 31, 2024, and the related consolidated statements of operations and comprehensive loss, of changes in stockholders’ equity (deficit) and of cash flows for the year then ended, including the related notes (collectively referred to as the“consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024, and the results of its operations and its cash flows for the year then ended in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s consolidated financial statements based on our audit. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit of these consolidated financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audit we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audit included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audit provides a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Valuation of Stock Option Grants

As described in Notes 2 and 11 to the consolidated financial statements, the Company measures compensation expense for stock-based awards to employees, non-employees and directors based upon the awards’ initial grant-date fair values. Stock-based compensation expense for stock options is recorded over the requisite service period. The fair values of stock option grants with only a service condition are estimated as of the date of grant by applying the Black-Scholes option valuation model (“Black-Scholes model”). The Black-Scholes model incorporates assumptions as to stock price volatility, the expected life of options, a risk-free interest rate, and dividend yield. The Black-Scholes model is affected by the stock price on the date of the grant, as well as assumptions regarding a number of variables. These variables include the expected term of the option, expected risk-free interest rate, expected volatility of common stock, and expected dividend yield. The assumptions for the expected term of the option and expected volatility of common stock are the two assumptions that significantly affect the grant date fair value. The Company’s stock-based compensation expense related to stock options for the year ended December 31, 2024 was $6.4 million.

The principal considerations for our determination that performing procedures relating to the valuation of stock option grants is a critical audit matter are (i) the significant judgment by management when developing the fair value estimate of the stock option grants and (ii) a high degree of auditor judgment, subjectivity, and effort in performing procedures and evaluating management’s significant assumption related to expected volatility.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included, among others (i) testing management’s process for developing the fair value estimate of the stock option grants; (ii) evaluating the appropriateness of the Black-Scholes model; (iii) testing the completeness and accuracy of the underlying data used in the estimate of the fair value of the stock option grants; (iv) testing stock-based compensation expense for a sample of stock options granted by obtaining and inspecting source documents, such as grant award letters and Board of Director minutes; and (v) evaluating the reasonableness of the significant assumption used by management related to expected volatility. Evaluating management’s assumption related to expected volatility involved considering (i) the historical stock prices and volatilities of the Company; (ii) the historical stock prices and volatilities of the peer group data by utilizing data obtained from an independent-third party source; and (iii) whether the assumption was consistent with evidence obtained in other areas of the audit.

/s/Pricewaterhouse Coopers LLP

San Diego, California

March 3, 2025

We have served as the Company’s auditor since 2024.