Sec Form 4 Filing - ROTHBERG JONATHAN M @ Quantum-Si Inc - 2022-06-14

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person ROTHBERG JONATHAN M 2. Issuer Name and Ticker or Trading Symbol Quantum-Si Inc [ QSI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) Interim CEO (Last) (First) (Middle) C/O QUANTUM-SI INCORPORATED, 530 OLD WHITFIELD STREET 3. Date of Earliest Transaction (MM/DD/YY) 06/14/2022 (Street) GUILFORD, CT06437 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Class A Common Stock 06/14/2022 P 25,561 A $ 3.0975( 1 ) 2,568,443 D Class A Common Stock 6,230,108 I By 2012 JMR Trust Common, LLC( 2 ) Class A Common Stock 1,250,000 I By NVR TR, LLC( 2 )( 3 ) Class A Common Stock 1,250,000 I By JNR TR, LLC( 2 )( 3 ) Class A Common Stock 1,250,000 I By JAR TR, LLC( 2 )( 3 ) Class A Common Stock 1,250,000 I By GBR TR, LLC( 2 )( 3 ) Class A Common Stock 1,250,000 I By EJR TR, LLC( 2 )( 3 ) Class A Common Stock 1,917,067 I By 23rd Century Capital LLC( 2 ) Class A Common Stock 273,422 I By Bonnie E Gould Rothberg MD( 2 ) Class B Common Stock 17,943,750 I By 4C Holdings I, LLC( 2 ) Class B Common Stock 1,993,750 I By 4C Holdings V, LLC( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ROTHBERG JONATHAN M C/O QUANTUM-SI INCORPORATED 530 OLD WHITFIELD STREET GUILFORD, CT06437 X X Interim CEO Signatures /s/ Samantha Silver, Attorney-in-Fact 06/16/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents the weighted average purchase price per share. The shares were purchased at prices ranging from $3.065 to $3.1261 per share. Full information regarding the number of shares purchased at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer. ( 2 )Dr. Rothberg is the sole manager of 4C Holdings I, LLC, 4C Holdings V, LLC, 2012 JMR Trust Common, LLC, NVR TR, LLC, JNR TR, LLC, JAR TR, LLC, GBR TR, LLC and EJR TR, LLC. Dr. Rothberg is the spouse of Bonnie E. Gould Rothberg MD and Dr. Rothberg's son is the manager of 23rd Century Capital LLC. Dr. Rothberg disclaims beneficial ownership of the shares held by his spouse and 23rd Century Capital LLC. ( 3 )Shares previously held by 2012 JMR Trust Common, LLC that were distributed to NVR TR, LLC, JNR TR, LLC, JAR TR, LLC, GBR TR, LLC and EJR TR, LLC.

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