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

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(Neutral)
Form Type
4

Rhea-AI Filing Summary

Quanterix Corp’s Chief Technology Officer, Michael Francis Miller, reported multiple equity compensation transactions on August 15, 2026. He exercised or converted restricted stock units into 1,558 shares of common stock, with the RSUs converting into common stock on a one-for-one basis. In related transactions, 467 common shares were delivered or withheld at $2.59 per share for payment of exercise price or tax liability. The mix of RSU conversions and share withholdings results in a largely administrative change in Miller’s reported holdings rather than a market purchase or sale.

Positive

  • None.

Negative

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Insider Miller Michael Francis
Role Chief Technology Officer
Type Security Shares Price Value
Exercise Restricted Stock Unit F2 81 $0.00 $0.00
Exercise Restricted Stock Unit F3 136 $0.00 $0.00
Exercise Restricted Stock Unit F4 135 $0.00 $0.00
Exercise Restricted Stock Unit F5 372 $0.00 $0.00
Exercise Restricted Stock Unit F6 834 $0.00 $0.00
Exercise Common Stock F1 81 -- --
Exercise Price or Tax Liability Common Stock 25 $2.59 $64.75
Exercise Common Stock F1 136 -- --
Exercise Price or Tax Liability Common Stock 41 $2.59 $106.19
Exercise Common Stock F1 135 -- --
Exercise Price or Tax Liability Common Stock 41 $2.59 $106.19
Exercise Common Stock F1 372 -- --
Exercise Price or Tax Liability Common Stock 111 $2.59 $287.49
Exercise Common Stock F1 834 -- --
Exercise Price or Tax Liability Common Stock 249 $2.59 $644.91
Holdings After Transaction: Restricted Stock Unit — 36,791 shares (Direct); Common Stock — 37,250 shares (Direct)
Footnotes (6)
  1. F1. Restricted stock units convert into common stock on a one-for-one basis.
  2. F2. 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. F3. 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. F4. 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. F5. 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. F6. 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.
RSU shares converted 1,558 shares Total underlying shares from derivative exercises/conversions (code M) reported
Shares withheld for taxes/exercise 467 shares Total shares delivered or withheld under code F for exercise price or tax liability
Withholding price per share $2.59 per share Price for common shares delivered or withheld in code F transactions
RSU grant Feb 6, 2023 3,929 RSUs Grant vesting 25% after one year, 75% in 36 monthly installments
RSU grant Mar 15, 2023 6,566 RSUs Grant vesting 25% after one year, 75% in 36 monthly installments
RSU grant Feb 4, 2025 40,036 RSUs Grant vesting 25% after one year, 75% in 36 monthly installments
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.
exercise or conversion of derivative security financial
"transaction_code_description: Exercise or conversion of derivative security"
Payment of exercise price or tax liability financial
"transaction_code_description: Payment of exercise price or tax liability by delivering"
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.

FAQ

What insider transactions did Quanterix (QTRX) CTO Michael Francis Miller report on August 15, 2026?

Michael Francis Miller exercised or converted restricted stock units into 1,558 shares of Quanterix common stock and had 467 shares delivered or withheld to cover exercise price or tax liability at $2.59 per share, reflecting equity compensation activity.

How many Quanterix (QTRX) RSUs did Michael Francis Miller convert to common stock?

He converted restricted stock units into 1,558 shares of Quanterix common stock. These RSUs stem from several grants between 2023 and 2025, each vesting over time, and they convert into common stock on a one-for-one basis as they vest.

How many Quanterix (QTRX) shares were withheld for taxes or exercise price in this Form 4?

A total of 467 shares of Quanterix common stock were delivered or withheld to pay exercise price or tax liability at $2.59 per share. These are reported under transaction code F, which covers such non-market dispositions.

What is the conversion ratio of Michael Francis Miller’s Quanterix (QTRX) restricted stock units?

His restricted stock units convert into Quanterix common stock on a one-for-one basis. Each vested RSU therefore results in the issuance of one share of common stock, as explicitly stated in the Form 4 footnotes.

Which Quanterix (QTRX) RSU grants are involved in Michael Francis Miller’s August 15, 2026 transactions?

The RSU exercises relate to grants of 3,929, 6,566, 6,494, 17,878, and 40,036 RSUs awarded between 2023 and 2025. Each grant vests 25% after one year, with the remaining 75% vesting in 36 equal monthly installments thereafter.

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Learn about SEC filing dates
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)
08/15/2026
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 Stock08/15/2026M81A(1)36,240D
Common Stock08/15/2026F25D$2.5936,215D
Common Stock08/15/2026M136A(1)36,351D
Common Stock08/15/2026F41D$2.5936,310D
Common Stock08/15/2026M135A(1)36,445D
Common Stock08/15/2026F41D$2.5936,404D
Common Stock08/15/2026M372A(1)36,776D
Common Stock08/15/2026F111D$2.5936,665D
Common Stock08/15/2026M834A(1)37,499D
Common Stock08/15/2026F249D$2.5937,250D
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$0.0008/15/2026M81 (2) (2)Common Stock81$0.00517D
Restricted Stock Unit$0.0008/15/2026M136 (3) (3)Common Stock136$0.00981D
Restricted Stock Unit$0.0008/15/2026M135 (4) (4)Common Stock135$0.002,441D
Restricted Stock Unit$0.0008/15/2026M372 (5) (5)Common Stock372$0.007,829D
Restricted Stock Unit$0.0008/15/2026M834 (6) (6)Common Stock834$0.0025,023D
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-Fact08/17/2026
** 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)