[Form 4] Quantum-Si Inc Insider Trading Activity

Rhea-AI Filing Summary

Quantum-Si Inc (QSI) insider sale summary: John S. Vieceli, identified as Chief Product Officer and a director-level reporting person, disclosed sales of Class A common stock tied to the vesting of previously granted restricted stock units. On 09/22/2025 he sold 9,843 shares at a weighted average price of $1.6826 per share and reported beneficial ownership of 832,743 shares after that sale. On 09/23/2025 he sold another 9,843 shares at a weighted average price of $1.635 per share and reported beneficial ownership of 822,900 shares thereafter. The filing states these sales were mandatory "sell-to-cover" transactions to satisfy federal, state and local withholding taxes and that the reporting individual could not alter that provision.

Positive

• Sales were mandatory sell-to-cover for RSU tax withholding, indicating these were not discretionary market exits
• Reporting person retains substantial post-transaction ownership (822,900 shares), signaling continued alignment with shareholders

Negative

• Total holdings decreased by 19,686 shares due to the two sell transactions, modestly reducing insider stake

Insights

Financial Analyst

TL;DR: Two small, tax-mandated sales occurred; remaining holdings remain substantial, indicating ongoing insider alignment with shareholder value.

The transactions are described as mandatory sell-to-cover actions tied to RSU vesting rather than discretionary dispositions. Each sale was 9,843 shares, reducing beneficial ownership from 832,743 to 822,900 shares. Because the sales are for tax withholding, they do not necessarily signal changed sentiment about the company. The monetary scale relative to total holdings appears modest based on reported post-transaction holdings.

Corporate Governance Expert

TL;DR: Disclosures follow standard Form 4 practice; mandatory sell-to-cover routing is clearly explained in the filing.

The Form 4 clearly identifies the reporter, relationship to the issuer, and the nature of the transactions as mandatory sell-to-cover for RSU tax obligations. The filing provides weighted average prices and post-transaction beneficial ownership counts, supporting transparency. No indication of accelerated or discretionary large-scale sales is present in the disclosed lines.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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

1. Name and Address of Reporting Person^*

Vieceli John S.

(Last) (First) (Middle)

C/O QUANTUM-SI INCORPORATED

29 BUSINESS PARK DRIVE

(Street)

BRANFORD CT 06405

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Quantum-Si Inc [ QSI ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Product Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/22/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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	09/22/2025		S(1)		9,843	D	$1.6826(2)	832,743	D
Class A Common Stock	09/23/2025		S(1)		9,843	D	$1.635(3)	822,900	D

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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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

Explanation of Responses:

1. Represents shares sold pursuant to a mandatory Quantum-Si sell-to-cover provision for required federal, state and local withholding taxes in connection with the vesting of previously granted restricted stock units. Individual is not able to alter this mandatory sell-to-cover provision that is enacted at the grant date of the related restricted stock unit award.

2. Represents the weighted average sales price per share. The shares sold at prices ranging from $1.64 to $1.72 per share. Full information regarding the number of shares sold 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.

3. Represents the weighted average sales price per share. The shares sold at prices ranging from $1.57 to $1.79 per share. Full information regarding the number of shares sold 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.

	/s/ Christian LaPointe, Ph.D., Attorney-in-Fact.	09/24/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What transactions did John S. Vieceli report on Form 4 for QSI?

He reported two sales of Class A common stock: 9,843 shares on 09/22/2025 and 9,843 shares on 09/23/2025.

Why were the QSI shares sold by the reporting person?

The filing states the sales were mandatory sell-to-cover transactions to satisfy federal, state and local withholding taxes on vested restricted stock units.

What prices were received for the shares sold by the QSI insider?

The weighted average sales prices were $1.6826 per share for the 09/22/2025 sale and $1.635 per share for the 09/23/2025 sale; ranges provided were $1.64–$1.72 and $1.57–$1.79 respectively.

How many QSI shares does the reporting person own after these transactions?

Beneficial ownership was reported as 832,743 shares after the 09/22/2025 sale and 822,900 shares after the 09/23/2025 sale.

Do these Form 4 disclosures indicate discretionary insider selling?

No. The filing explicitly describes the transactions as mandatory sell-to-cover for RSU tax withholding, not discretionary sales.