Quanterix (QTRX) CTO reports RSU vesting and tax share withholding

Rhea-AI Filing Summary

Quanterix Corp Chief Technology Officer Michael Francis Miller reported routine equity compensation activity involving restricted stock units. He exercised RSUs that converted into 130 shares of common stock on a one-for-one basis and a portion of the resulting shares, 39 in total, was disposed of to cover tax obligations. These transactions did not involve any open-market buying or selling and reflect standard mechanisms for settling equity awards and related taxes.

Insider Trade Summary

130 shares exercised/converted

Mixed 3 txns

Insider Miller Michael Francis

Role Chief Technology Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	130	$0.00	--
Exercise	Common Stock	130	$0.00	--
Tax Withholding	Common Stock	39	$4.32	$168.48

Holdings After Transaction: Restricted Stock Unit — 289 shares (Direct, null); Common Stock — 35,016 shares (Direct, null)

Footnotes (1)

1. Restricted stock units convert into common stock on a one-for-one basis. On September 23, 2022, the reporting person was granted 6,278 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the last day of each month thereafter.

Key Figures

RSU conversion: 130 shares Tax-withholding shares: 39 shares Tax-withholding price: $4.32 per share +1 more

4 metrics

RSU conversion 130 shares Restricted stock units converted into common stock on June 30, 2026

Tax-withholding shares 39 shares Shares delivered to cover tax liability on June 30, 2026

Tax-withholding price $4.32 per share Price per share for 39-share tax-withholding disposition

Original RSU grant 6,278 RSUs Grant on September 23, 2022 with graded vesting schedule

Key Terms

Restricted Stock Unit, tax-withholding disposition, derivative exercise/conversion, vesting

4 terms

Restricted Stock Unit financial

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

A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.

tax-withholding disposition financial

"Payment of exercise price or tax liability by delivering securities."

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

derivative exercise/conversion financial

"Exercise or conversion of derivative security."

vesting financial

"Vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments."

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 07/02/2026 - 04:02 PM Accepted by SEC EDGAR 07/02/2026 - 04:01 PM Learn about SEC filing dates

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^*

Miller Michael Francis

(Last) (First) (Middle)

C/O QUANTERIX CORPORATION

900 MIDDLESEX TURNPIKE

(Street)

BILLERICA MASSACHUSETTS 01821

(City) (State) (Zip)

UNITED STATES

(Country)

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 Technology Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/30/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	06/30/2026		M		130	A	(1)	35,016	D
Common Stock	06/30/2026		F		39	D	$4.32	34,977	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
Restricted Stock Unit	$0.00	06/30/2026		M			130	(2)	(2)	Common Stock	130	$0.00	289	D

Explanation of Responses:

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

2. On September 23, 2022, the reporting person was granted 6,278 restricted stock units, vesting 25% on the first anniversary of the grant date, with the remaining 75% vesting in 36 equal monthly installments on the last day of each month thereafter.

Remarks:

	/s/ Meghan Shevlin, Attorney-in-Fact	07/01/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transactions did Quanterix (QTRX) CTO Michael Francis Miller report?

He reported routine equity compensation activity, including RSUs converting into 130 common shares and a 39-share tax-withholding disposition. These are administrative transactions tied to stock-based compensation, not open-market buying or selling of Quanterix stock.

How many Quanterix (QTRX) shares were acquired through RSU conversion?

Restricted stock units converted into 130 shares of Quanterix common stock on a one-for-one basis. This RSU conversion reflects previously granted equity vesting rather than a new cash purchase of shares on the open market by the CTO.

Why were 39 Quanterix (QTRX) shares disposed of in this Form 4?

The 39-share disposition was reported as a tax-withholding transaction. Shares were delivered to satisfy tax liabilities associated with the RSU-related share delivery, which is a common, non-market method for employees to cover withholding obligations on equity compensation.

Did the Quanterix (QTRX) CTO make any open-market stock purchases or sales?

No open-market purchases or sales were reported. The Form 4 shows a derivative exercise/conversion of restricted stock units into common shares and a tax-withholding disposition, both standard compensation-related events rather than discretionary market trades by the executive.

What do the restricted stock unit terms mean for Quanterix (QTRX) CTO’s equity?

The RSUs convert into common stock on a one-for-one basis. A prior grant of 6,278 RSUs vests 25% after one year and the remaining 75% in 36 equal monthly installments, gradually delivering shares as long as vesting conditions are met.