Quanterix (NASDAQ: QTRX) CFO uses 4,395 shares for RSU taxes

Rhea-AI Filing Summary

Quanterix Corporation’s Chief Financial Officer, Sriram Vandana, reported a routine tax-related share withholding. On February 4, 2026, 4,395 shares of common stock were withheld by Quanterix to cover tax obligations from the vesting of 12,678 restricted stock units (RSUs).

After this transaction, the CFO beneficially owned 81,618 shares of Quanterix common stock, which includes 55,884 RSUs. This filing reflects a non-open-market transaction coded "F," indicating shares retained for taxes rather than a discretionary sale into the market.

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

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Sriram Vandana

(Last) (First) (Middle)

C/O QUANTERIX CORPORATION

900 MIDDLESEX TURNPIKE

(Street)

BILLERICA MA 01821

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Quanterix Corp [ QTRX ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
02/04/2026

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
Common Stock	02/04/2026		F		4,395(1)	D	$0.00	81,618(2)	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. Shares withheld by Quanterix Corporation solely to cover tax obligations upon vesting of 12,678 restricted stock units (RSUs).

2. Includes 55,884 RSUs

Remarks:

	/s/ Bonnie McManus, as Attorney-in-Fact	02/06/2026
	** 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).
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FAQ

What insider transaction did Quanterix (QTRX) CFO report on February 4, 2026?

Quanterix’s CFO, Sriram Vandana, reported a tax-withholding transaction on February 4, 2026. The company withheld 4,395 common shares to satisfy tax obligations triggered by the vesting of 12,678 restricted stock units, rather than a discretionary open-market sale of shares.

How many Quanterix (QTRX) shares does the CFO own after this Form 4 filing?

After the reported transaction, Quanterix’s CFO beneficially owns 81,618 common shares. This total includes 55,884 restricted stock units (RSUs), reflecting both currently held stock and unvested equity awards that are scheduled to convert into shares over time, subject to plan conditions.

Was the Quanterix (QTRX) CFO’s Form 4 transaction an open-market sale?

No, the transaction was not an open-market sale. It is coded “F,” meaning shares were withheld by Quanterix solely to cover tax obligations upon vesting of 12,678 restricted stock units, a common administrative mechanism for handling equity-compensation-related taxes.

What do the 12,678 RSUs mentioned in the Quanterix (QTRX) Form 4 represent?

The 12,678 RSUs represent restricted stock units that vested for the Quanterix CFO. When they vested, the company withheld 4,395 shares to cover associated taxes. RSUs are equity awards that convert into shares upon vesting, subject to employment and plan terms.

What is the significance of the 55,884 RSUs held by the Quanterix (QTRX) CFO?

The 55,884 RSUs are part of the CFO’s remaining equity holdings. These awards, included in the 81,618 beneficially owned shares figure, are expected to convert into common stock as they vest over time, aligning the executive’s compensation with Quanterix’s long-term performance.