SEC FORM 4

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).

1. Name and Address of Reporting Person^*

Sriram Vandana

(Last)

(First)

(Middle)

C/O QUANTERIX CORPORATION

900 MIDDLESEX TURNPIKE

(Street)

BILLERICA

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
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).
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