STOCK TITAN

Quanterix Corp (QTRX) CTO converts 1,558 RSUs, withholds shares for taxes

(Neutral)
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Quanterix Corp Chief Technology Officer Michael Francis Miller reported compensation-related equity activity. On July 15, 2026 he converted 1,558 restricted stock units into common stock and had 467 shares withheld to satisfy tax obligations. After these non–open-market transactions, he directly owns 35,058 Quanterix common shares and continues to hold multiple unvested RSU awards.

Positive

  • None.

Negative

  • None.
Insider Miller Michael Francis
Role Chief Technology Officer
Type Security Shares Price Value
Exercise Restricted Stock Unit 81 $0.00 --
Exercise Restricted Stock Unit 136 $0.00 --
Exercise Restricted Stock Unit 135 $0.00 --
Exercise Restricted Stock Unit 372 $0.00 --
Exercise Restricted Stock Unit 834 $0.00 --
Exercise Common Stock 81 -- --
Tax Withholding Common Stock 25 $4.24 $106.00
Exercise Common Stock 136 -- --
Tax Withholding Common Stock 41 $4.24 $173.84
Exercise Common Stock 135 -- --
Tax Withholding Common Stock 41 $4.24 $173.84
Exercise Common Stock 372 -- --
Tax Withholding Common Stock 111 $4.24 $470.64
Exercise Common Stock 834 -- --
Tax Withholding Common Stock 249 $4.24 $1K
Holdings After Transaction: Restricted Stock Unit — 598 shares (Direct); Common Stock — 35,058 shares (Direct)
Footnotes (1)
  1. Restricted stock units convert into common stock on a one-for-one basis. On February 6, 2023, the reporting person was granted 3,929 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 15th day of each month thereafter. On March 15, 2023, the reporting person was granted 6,566 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 15th day of each month thereafter. On February 2, 2024, the reporting person was granted 6,494 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 15th day of each month thereafter. On May 21, 2024, the reporting person was granted 17,878 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 15th day of each month thereafter. On February 4, 2025, the reporting person was granted 40,036 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 15th day of each month thereafter.
RSUs converted to common stock 1,558 shares Restricted stock units exercised into common stock on July 15, 2026
Shares withheld for taxes 467 shares Tax-withholding dispositions related to RSU vesting on July 15, 2026
Direct common shares after transactions 35,058 shares Direct ownership of Quanterix common stock following July 15, 2026 transactions
Tax withholding share price $4.24 per share Price used for tax-withholding dispositions of common stock on July 15, 2026
Largest remaining RSU award 25,857 units Restricted stock units remaining outstanding under one grant after July 15, 2026
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 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 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.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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FAQ

What insider equity transactions did Quanterix (QTRX) report for its CTO?

Quanterix reported that CTO Michael Francis Miller had 1,558 restricted stock units convert into common stock on July 15, 2026. In connection with this vesting, 467 shares were delivered to cover tax obligations, and the remaining shares increased his direct common stock holdings.

How many Quanterix (QTRX) shares does the CTO hold after these transactions?

Following the July 15, 2026 equity transactions, CTO Michael Francis Miller directly owns 35,058 Quanterix common shares. This figure reflects RSU conversions into stock and related tax-withholding share dispositions reported in the Form 4 filing for that date.

Were the Quanterix (QTRX) CTO’s Form 4 transactions open-market buys or sells?

The reported transactions were not open-market trades. They consist of RSU conversions into common stock (code M) and tax-withholding dispositions (code F), where 467 shares were delivered to satisfy tax liabilities tied to equity vesting.

How many restricted stock units did the Quanterix (QTRX) CTO have vest?

On July 15, 2026, Michael Francis Miller had 1,558 restricted stock units convert into Quanterix common stock. The RSUs convert on a one-for-one basis, so each vested unit produced one common share, subject to shares withheld for associated tax obligations.

Does the Quanterix (QTRX) CTO still hold unvested restricted stock units?

Yes. After the reported vesting events, Michael Francis Miller continues to hold several unvested RSU awards, including one grant with 25,857 restricted stock units remaining outstanding, which are scheduled to vest over time according to their original grant terms.
SEC Form 4
FORM 4UNITED 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)
Director10% Owner
XOfficer (give title below)Other (specify below)
Chief Technology Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
07/15/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock07/15/2026M81A(1)35,058D
Common Stock07/15/2026F25D$4.2435,033D
Common Stock07/15/2026M136A(1)35,169D
Common Stock07/15/2026F41D$4.2435,128D
Common Stock07/15/2026M135A(1)35,263D
Common Stock07/15/2026F41D$4.2435,222D
Common Stock07/15/2026M372A(1)35,594D
Common Stock07/15/2026F111D$4.2435,483D
Common Stock07/15/2026M834A(1)36,317D
Common Stock07/15/2026F249D$4.2436,068D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Restricted Stock Unit$0.0007/15/2026M81 (2) (2)Common Stock81$0.00598D
Restricted Stock Unit$0.0007/15/2026M136 (3) (3)Common Stock136$0.001,117D
Restricted Stock Unit$0.0007/15/2026M135 (4) (4)Common Stock135$0.002,576D
Restricted Stock Unit$0.0007/15/2026M372 (5) (5)Common Stock372$0.008,201D
Restricted Stock Unit$0.0007/15/2026M834 (6) (6)Common Stock834$0.0025,857D
Explanation of Responses:
1. Restricted stock units convert into common stock on a one-for-one basis.
2. On February 6, 2023, the reporting person was granted 3,929 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 15th day of each month thereafter.
3. On March 15, 2023, the reporting person was granted 6,566 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 15th day of each month thereafter.
4. On February 2, 2024, the reporting person was granted 6,494 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 15th day of each month thereafter.
5. On May 21, 2024, the reporting person was granted 17,878 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 15th day of each month thereafter.
6. On February 4, 2025, the reporting person was granted 40,036 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 15th day of each month thereafter.
Remarks:
/s/ Meghan Shevlin, Attorney-in-Fact07/16/2026
** Signature of Reporting PersonDate
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)