Quantum-Si officer proposes $5,805.67 share sale

The notice says Quantum-Si required the tax-withholding sale through a sell-to-cover transaction, rather than a discretionary trade by the officer.

Available on EDGAR 09/23/2026 - 07:29 PM EDT Accepted by SEC EDGAR 09/23/2026 - 07:28 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Quantum-Si Inc officer Jeffry R. Keyes filed notice of a proposed sale of 7,665 Class A common shares, with an aggregate market value of $5,805.67 and an approximate sale date of September 21, 2026. The notice identifies 21,676 shares acquired through restricted stock unit vesting on September 20, 2026, as equity compensation for services rendered. Its remarks state that the sale is mandated by the issuer’s election to satisfy tax withholding through a sell-to-cover transaction and is not a discretionary trade by Keyes.

Key Figures

Proposed shares to be sold: 7,665 Class A common shares Aggregate market value of proposed sale: $5,805.67 Shares acquired through restricted stock unit vesting: 21,676 shares

3 metrics

Proposed shares to be sold 7,665 Class A common shares Approximate sale date: September 21, 2026

Aggregate market value of proposed sale $5,805.67 For the proposed sale of 7,665 Class A common shares

Shares acquired through restricted stock unit vesting 21,676 shares September 20, 2026; equity compensation for services rendered

Key Terms

sell to cover transaction, Restricted Stock Unit Vesting, tax withholding obligations

3 terms

sell to cover transaction financial

"satisfaction of tax withholding obligations through a sell to cover transaction"

Restricted Stock Unit Vesting financial

"09/20/2026 | Restricted Stock Unit Vesting"

tax withholding obligations financial

"Shares sold to cover tax withholding obligations"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many QSI shares did Jeffry R. Keyes propose to sell?

Quantum-Si Inc officer Jeffry R. Keyes reported a proposed sale of 7,665 Class A common shares, with an aggregate market value of $5,805.67 and an approximate sale date of September 21, 2026.

Why is the QSI officer’s sale happening?

The notice says the sale covers tax withholding obligations tied to restricted stock unit vesting. The issuer elected to require a sell-to-cover transaction, and the remarks state it was not a discretionary trade by Keyes.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001557736
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Quantum-Si Inc
SEC File Number	001-39486
Address of Issuer	29 BUSINESS PARK DRIVE BRANFORD CONNECTICUT 06405
Phone	(203) 458-7100
Name of Person for Whose Account the Securities are To Be Sold	Keyes Jeffry R.
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Class A Common Stock	Morgan Stanley Smith Barney LLC 1 New York Plaza 38th Floor New York NY 10004	7665	5805.67	198946412	09/21/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Class A Common Stock	09/20/2026	Restricted Stock Unit Vesting	Quantum-Si Incorporated			21676	09/20/2026	Equity compensation for services rendered

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks	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.
Date of Notice	09/23/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Christian LaPointe, Ph.D., Attorney-in-Fact
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)