Quanterix (QTRX) CTO exercises 130 RSUs, with 39 shares used for taxes

Rhea-AI Filing Summary

Quanterix Corp’s Chief Technology Officer Michael Francis Miller reported compensation-related equity transactions, not open-market trades. He exercised restricted stock units (RSUs) that converted into 130 shares of common stock, then 39 of those shares were disposed of to cover tax obligations.

After these transactions, he directly holds 33,834 shares of common stock and 419 RSUs. The RSUs were granted on September 23, 2022 and vest over four years, with 25% on the first anniversary and the remaining 75% in 36 equal monthly installments.

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	$3.06	$119.34

Holdings After Transaction: Restricted Stock Unit — 419 shares (Direct, null); Common Stock — 33,834 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

RSUs exercised: 130 shares Shares for tax withholding: 39 shares Common shares held after: 33,834 shares +3 more

6 metrics

RSUs exercised 130 shares Restricted stock units converted into common stock on May 31, 2026

Shares for tax withholding 39 shares Common stock disposed to cover tax obligations on May 31, 2026

Common shares held after 33,834 shares Direct common stock holdings after reported transactions

RSUs held after 419 units Restricted stock units remaining after the RSU conversion

Original RSU grant 6,278 units Grant to CTO on September 23, 2022 with time-based vesting

Tax disposition price $3.06 per share Price used for 39-share tax-withholding disposition

Key Terms

Restricted stock units, tax-withholding disposition, derivative security, vesting

4 terms

Restricted stock units financial

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

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

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 security financial

"Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

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.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Form 4 Insider Transactions: What Each Field Means →

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)
05/31/2026

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	05/31/2026		M		130	A	(1)	33,834	D
Common Stock	05/31/2026		F		39	D	$3.06	33,795	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	05/31/2026		M			130	(2)	(2)	Common Stock	130	$0.00	419	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	06/01/2026
	** 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) report for its CTO?

Quanterix’s CTO Michael Francis Miller exercised 130 restricted stock units into common shares, then 39 shares were disposed of to satisfy tax obligations. These transactions are compensation-related events, not open-market buying or selling of Quanterix stock.

How many Quanterix (QTRX) shares does the CTO hold after this Form 4?

After the reported transactions, Quanterix CTO Michael Francis Miller directly holds 33,834 shares of common stock. In addition, he holds 419 restricted stock units that may convert into common shares in the future as they continue to vest.

What does the 39-share tax-withholding disposition mean for Quanterix (QTRX)?

The 39-share tax-withholding disposition means shares were delivered to cover tax liabilities from equity vesting, rather than being sold on the open market. It reflects a mechanical tax payment process and does not indicate a discretionary sale of Quanterix stock by the CTO.

What RSU grant is referenced in the Quanterix (QTRX) Form 4?

The Form 4 notes a grant of 6,278 restricted stock units to the CTO on September 23, 2022. These RSUs vest 25% on the first anniversary of the grant date and the remaining 75% in 36 equal monthly installments on the last day of each month.

How do Quanterix (QTRX) RSUs convert into common stock for the CTO?

The filing states that restricted stock units convert into Quanterix common stock on a one-for-one basis. As RSUs vest over time, each vested unit becomes one share of common stock, subject to any required share withholding for associated tax obligations.