Quanterix Corp (QRX) Form 4 Filing

TL;DR

QRX insider William P. Donnelly filed a Form 4 on 4/7/26 for 4/1/26 transactions.

AI Summary

On April 7, 2026, William P. Donnelly filed a Form 4 with the SEC, reporting changes in beneficial ownership of Quanterix Corp securities. The filing details transactions that occurred on April 1, 2026. Specific details regarding the nature of the transactions and the number of shares involved are not provided in this summary.

Why It Matters

Form 4 filings indicate changes in stock ownership by company insiders, which can signal their confidence or lack thereof in the company's future performance.

Risk Assessment

Risk Level: low — This is a routine filing reporting changes in beneficial ownership by an insider, with no immediate indication of significant risk.

Key Players & Entities

• William P. Donnelly (person) — Insider filing the Form 4
• Quanterix Corp (company) — Issuer of the securities
• 0001207928-26-000004 (filing_id) — SEC Accession Number
• 2026-04-07 (date) — Filing Date
• 2026-04-01 (date) — Period of Report

FAQ

Filing Documents

• primarydocument.html (4)
• primarydocument.xml (4) — 4KB
• wdonnellypoa.txt (EX-24) — 3KB
• 0001207928-26-000004.txt ( ) — 8KB

From the Filing

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 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 * DONNELLY WILLIAM P (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) X Director 10% Owner X Officer (give title below) Other (specify below) Executive Chair 2a. Foreign Trading Symbol 3. Date of Earliest Transaction (Month/Day/Year) 04/01/2026 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 04/01/2026 A 6,178 (1) A $ 0.00 154,127 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 Explanation of Responses: 1. Consists of stock granted in lieu of cash fees for service on the Company's Board of Directors and committees thereof for the first quarter of 2026. Remarks: /s/ Bonnie McManus, as Attorney-in-Fact 04/03/2026 ** 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)