Quantum-Si files Form 144 for Class A stock sale

Quantum-Si Incorporated submitted a Form 144 notice relating to proposed sales of Class A Common Stock.

Accepted by SEC EDGAR 03/24/2026 - 09:14 AM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Quantum-Si Incorporated submitted a Form 144 notice relating to proposed sales of Class A Common Stock. The filing lists a sale of 21,927 shares on 12/22/2025 and discloses vested equity items tied to restricted stock unit vesting of 10,838 and 44,271 shares on 03/15/2024 and 03/12/2025, respectively. The broker listed is Morgan Stanley Smith Barney LLC.

FAQ

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

What does Quantum-Si's (QSI) Form 144 report show?

It reports a broker-handled sale and upcoming vested shares from RSUs. The filing shows a sale of 21,927 shares on 12/22/2025 and RSU vesting amounts of 10,838 and 44,271 on 03/15/2024 and 03/12/2025.

Who is the broker handling the transactions in QSI's filing?

The broker named is Morgan Stanley Smith Barney LLC. The filing lists the broker's address as 1 New York Plaza, 38th Floor, New York, NY 10004 and associates it with the reported sale activity.

How many QSI shares were sold in the past three months per the filing?

21,927 shares were reported as sold on 12/22/2025. That quantity appears under "Securities Sold During The Past 3 Months" in the provided excerpt.

What restricted stock unit vesting amounts are disclosed in the QSI Form 144?

The filing lists RSU vesting amounts of 10,838 shares (vesting 03/15/2024) and 44,271 shares (vesting 03/12/2025) tied to equity compensation for services rendered.

Does the Form 144 specify how proceeds will be used for QSI?

The excerpt does not describe use of proceeds. It lists sale and vesting quantities and the broker; no cash‑flow treatment or allocation of proceeds is provided in the provided content.

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	0002032947
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	Vieceli John S.
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	21997	18416.17	196431273	03/20/2026	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	03/15/2024	Restricted Stock Unit Vesting	Quantum-Si Incorporated			10838	03/15/2024	Equity compensation for services rendered
Class A Common Stock	03/12/2025	Restricted Stock Unit Vesting	Quantum-Si Incorporated			44271	03/12/2025	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

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Morgan Stanley Smith Barney LLC 1 New York Plaza 38th Floor New York NY 10004	Class A Common Stock	12/22/2025	21927	27978.85

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	03/24/2026
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)