Quanterix (QTRX) CFO granted 149,810 PSUs and RSUs, with tax withholding

Rhea-AI Filing Summary

Quanterix Corp’s chief financial officer, Vandana Sriram, reported equity award and related tax transactions. The CFO received grants of 74,905 performance stock units and 74,905 restricted stock units at a stated price of $0 per unit. Footnotes explain that PSUs vest based on performance conditions and then in four equal annual installments starting on the first anniversary of the grant date, while the new RSU award also vests in four equal annual installments.

The filing also shows exercises of previously granted restricted stock units into common stock, along with share dispositions to cover tax obligations. Specifically, 514 and 263 RSUs were converted into common stock, and 179 and 92 common shares were withheld at $5.74 per share to satisfy tax liabilities. After these transactions, the CFO directly held 26,240 shares of Quanterix common stock.

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).

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)
02/15/2026

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	02/15/2026		M		514	A	(1)	26,248(2)	D
Common Stock	02/15/2026		F		179	D	$5.74	26,069	D
Common Stock	02/15/2026		M		263	A	(1)	26,332	D
Common Stock	02/15/2026		F		92	D	$5.74	26,240	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
Performance Stock Unit	$0.00	02/15/2026		A		74,905		(3)	12/31/2026	Common Stock	74,905	$0.00	74,905	D
Restricted Stock Unit	$0.00	02/15/2026		A		74,905		(4)	(4)	Common Stock	74,905	$0.00	74,905	D
Restricted Stock Unit	$0.00	02/15/2026		M			263	(5)	(5)	Common Stock	263	$0.00	4,734	D
Restricted Stock Unit	$0.00	02/15/2026		M			514	(6)	(6)	Common Stock	514	$0.00	12,339	D

Explanation of Responses:

1. Restricted stock units convert into common stock on a one-for-one basis.

2. The total shown no longer includes 55,884 unvested RSUs which the reporting person previously reported in Table I of Form 4 and will hereafter report in Table II of Form 4.

3. Each PSU award to vest (subject to the employee's continued service to the Company on the applicable vesting dates) according to the schedule and conditions set forth in the executive long-term incentive plan contained in the Company's 2026 Employee Equity Guidelines. After the award's performance conditions are satisfied, the PSUs will vest in four equal annual installments on each of the first four anniversaries of the Transaction Date.

4. The award vests in four equal annual installments on each of the first four anniversaries of the Transaction Date.

5. On August 21, 2023, the reporting person was granted 12,624 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in equal monthly installments of 6.25% on the monthly anniversary of the grant date thereafter.

6. On February 2, 2024, the reporting person was granted 24,675 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in equal monthly installments of 6.25% on the monthly anniversary of the grant date thereafter.

Remarks:

	/s/ Bonnie McManus, as Attorney-in-Fact	02/18/2026
	** 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).
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 transactions did Quanterix (QTRX) report for its CFO?

Quanterix reported its CFO received large equity awards and related tax transactions. The filing shows grants of performance stock units and restricted stock units, plus RSU conversions into common stock and share withholdings used to cover associated tax liabilities, all recorded on February 15, 2026.

How many PSUs and RSUs did the Quanterix (QTRX) CFO receive?

The CFO received 74,905 performance stock units and 74,905 restricted stock units. Both awards were recorded at a stated price of $0 per unit. These grants represent long-term equity incentives that vest over several years, subject to service and, for PSUs, performance conditions.

What are the vesting terms for the Quanterix (QTRX) CFO’s new equity awards?

The performance stock units vest after performance conditions are met, then in four equal annual installments starting on the first anniversary of the grant date. The new restricted stock units also vest in four equal annual installments on each of the first four anniversaries of the transaction date.

Did the Quanterix (QTRX) CFO sell common stock in the open market?

The filing shows dispositions coded as “F,” meaning shares were withheld to pay tax liabilities, not sold in open-market trades. Specifically, 179 and 92 common shares were delivered at $5.74 per share to satisfy tax obligations arising from equity award exercises.

How many Quanterix (QTRX) common shares does the CFO own after these transactions?

After the reported grants, conversions, and tax-withholding share deliveries, the CFO directly holds 26,240 shares of Quanterix common stock. This total reflects the net position following RSU exercises and the related share withholdings used to cover tax liabilities on February 15, 2026.

How do Quanterix (QTRX) restricted stock units convert into common stock?

Footnotes state that restricted stock units convert into Quanterix common stock on a one-for-one basis. When RSUs vest and are settled, each unit becomes one common share, subject to any shares withheld to pay taxes associated with the vesting or settlement event.