[Form 4] Quanterix Corp Insider Trading Activity

Rhea-AI Filing Summary

Quanterix Corporation’s Chief Financial Officer reported a routine share adjustment related to equity compensation. On 12/15/2025, 229 shares of common stock were withheld by Quanterix at a price of $7.41 per share to cover tax obligations that arose when 777 restricted stock units (RSUs) vested. After this tax withholding, the officer beneficially owns 85,977 shares of Quanterix common stock, which includes 84,652 RSUs. This filing reflects administrative handling of taxes on vested stock awards rather than an open-market purchase or sale.

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
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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)
12/15/2025

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
Common Stock	12/15/2025		F		229(1)	D	$7.41	85,977(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 777 restricted stock units (RSUs).

2. Includes 84,652 RSUs.

Remarks:

	/s/ Bonnie McManus, as Attorney-in-Fact	12/18/2025
	** 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 insider transaction did Quanterix (QTRX) report in this Form 4?

The Chief Financial Officer reported that 229 shares of Quanterix common stock were withheld on 12/15/2025 to cover tax obligations when 777 RSUs vested.

At what price were the Quanterix (QTRX) shares withheld for taxes?

The 229 shares of Quanterix common stock were withheld at a price of $7.41 per share to satisfy tax obligations tied to vested RSUs.

How many Quanterix (QTRX) shares does the CFO beneficially own after this transaction?

Following the reported transaction, the Chief Financial Officer beneficially owns 85,977 shares of Quanterix common stock, including 84,652 RSUs.

Was the Quanterix (QTRX) Form 4 transaction an open-market trade?

No. The Form 4 shows that shares were withheld by Quanterix solely to cover tax obligations arising from the vesting of 777 RSUs, rather than an open-market purchase or sale.

What is the relationship of the reporting person to Quanterix (QTRX)?

The reporting person is an officer of Quanterix Corporation, serving as its Chief Financial Officer, and filed the Form 4 as a single reporting person.

Does the Quanterix (QTRX) Form 4 mention Rule 10b5-1 trading plans?

The form includes a checkbox to indicate if a transaction was made under a Rule 10b5-1(c) trading plan, but the excerpt does not show that this box was selected.