QTRX

qtrx-20260302Quanterix Corpfalse000150327400015032742026-03-022026-03-02

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 2, 2026

QUANTERIX CORPORATION

(Exact name of registrant as specified in its charter)

Delaware001-3831920-8957988 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

900 Middlesex Turnpike

Billerica, MA 01821 (Address of principal executive offices) (Zip Code)

(617) 301-9400 (Registrant’s telephone number, including area code) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act:

Title of each classTrading symbol(s)Name of each exchange on which registered Common Stock, $0.001 par value per shareQTRXThe Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). Emerging Growth Company o If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Item 2.02    Results of Operations and Financial Condition. On March 2, 2026, Quanterix Corporation (“Quanterix”) issued a press release announcing its financial results for the fourth quarter and year ended December 31, 2025 (the “Earnings Release”). A copy of the Earnings Release is furnished as Exhibit 99.1 and is incorporated herein by reference. The information in this Form 8-K (including Exhibit 99.1 and 99.2) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 9.01    Financial Statements and Exhibits. (d)Exhibits

Exhibit No.Description 99.1Earnings Release dated March 2, 2026

99.2Slides from March 2, 2026 Earnings Call

104Cover Page Interactive Data File (embedded within the inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

QUANTERIX CORPORATION

By:/s/ VANDANA SRIRAM Vandana Sriram Chief Financial Officer

Date: March 2, 2026

qtrx-20260108Quanterix Corpfalse000150327400015032742026-01-082026-01-08

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): January 8, 2026

QUANTERIX CORPORATION

(Exact name of registrant as specified in its charter)

Delaware001-3831920-8957988 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

900 Middlesex Turnpike Billerica, MA 01821 (Address of principal executive offices) (Zip Code)

(617) 301-9400 (Registrant’s telephone number, including area code) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act:

Title of each class: Trading symbol(s): Name of each exchange on which registered:

Common Stock, $0.001 par value per shareQTRXThe Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging Growth Company o If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Item 2.02    Results of Operations and Financial Condition.

On January 8, 2026, Quanterix Corporation (“Quanterix”) issued a press release announcing certain executive transitions as described in Item 7.01 below (the “Release”). The Release also discusses Quanterix’s expectations regarding certain financial results for the fiscal year ended December 31, 2025. A copy of the Release is furnished as Exhibit 99.1 and is incorporated herein by reference. The information in this Item 2.02 of this Form 8-K (including the portion of Exhibit 99.1 that discusses Quanterix’s expectations regarding certain financial results for the fiscal year ended December 31, 2025) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 (the “Securities Act”) or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 5.02    Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On January 8, 2026, Masoud Toloue, Ph.D., President and Chief Executive Officer of Quanterix Corporation (“Quanterix” or the “Company”), entered into a separation agreement and release with the Company (the “Separation Agreement”), pursuant to which his employment as President and Chief Executive Officer of the Company has ended and he has resigned as a member of the Board of Directors (the “Board”), both effective as of January 19, 2026. In connection with his termination of employment, Dr. Toloue will receive severance benefits consistent with the termination-without-cause provisions of his employment agreement with the Company previously filed with the Securities and Exchange Commission. In addition, the Separation Agreement provides that (i) any outstanding but unvested portions of Dr. Toloue’s equity awards that would have vested on or prior to April 30, 2026 will accelerate and become fully-vested and exercisable on the effective date of Dr. Toloue’s separation, (ii) any such restricted stock units that vest in accordance with the preceding clause will be settled within 60 days following vesting, and (iii) any stock options, to the extent vested, may be exercised on or prior to December 31, 2026. A copy of the Separation Agreement is filed as Exhibit 10.1 and is incorporated herein by reference. Also on January 8, 2026, the Board appointed Everett Cunningham as President and Chief Executive Officer of the Company, effective January 19, 2026. Mr. Cunningham was also appointed to serve on the Board as a Class II director, with a term ending at the 2028 annual meeting of stockholders. Mr. Cunningham has s

qtrx-20251110false000150327400015032742025-11-102025-11-10

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): November 10, 2025

QUANTERIX CORPORATION

(Exact name of registrant as specified in its charter)

Delaware001-3831920-8957988 (State or other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

900 Middlesex Turnpike Billerica, MA 01821 (Address of principal executive offices) (Zip Code)

(617) 301-9400 (Registrant’s telephone number, including area code) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act:

Title of each class: Trading symbol(s): Name of each exchange on which registered:

Common Stock, $0.001 par value per shareQTRXThe Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). Emerging Growth Company o If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Item 2.02    Results of Operations and Financial Condition. On November 10, 2025, Quanterix Corporation (“Quanterix”) issued a press release announcing its financial results for the third quarter ended September 30, 2025 (the “Earnings Release”). A copy of the Earnings Release is furnished as Exhibit 99.1 and is incorporated herein by reference. The information in this Item 2.02 of this Form 8-K (including Exhibits 99.1 and 99.2) shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 9.01    Financial Statements and Exhibits. (d)Exhibits

Exhibit No.Description 99.1Earnings Release dated November 10, 2025

99.2Slides from November 10, 2025 Earnings Call

104Cover Page Interactive Data File (embedded within the inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

QUANTERIX CORPORATION

By:/s/ Vandana Sriram Vandana Sriram Chief Financial Officer

Date: November 10, 2025