This cooperation agreement (this “Agreement”) is made and entered into as of August 4, 2025, by and between Quanterix Corporation, a Delaware corporation (the “Company”), on the one hand, and Kent Lake PR LLC, a Puerto Rico limited liability company and the general partner of Kent Lake Partners LP, a Delaware limited partnership (together, “Kent Lake”), on the other hand. The Company and Kent Lake are each herein referred to as a “party” and collectively, the “parties.” Capitalized terms used herein and not otherwise defined have the meanings ascribed to them in Section 14 below.

WHEREAS, Kent Lake has been a stockholder of the Company since 2022, and Kent Lake and its Affiliates (together, the “Kent Lake Parties”) currently beneficially own 2,050,031 shares of common stock of the Company (“Common Stock”), constituting approximately 4.4% of the shares of outstanding Common Stock;

WHEREAS, on February 28, 2025, Kent Lake provided notice to the Company (the “February Notice”) of its intent to nominate three candidates for election to the board of directors of the Company (the “Board”) at the Company’s 2025 annual meeting of stockholders (the “2025 Annual Meeting”);

WHEREAS, on March 25, 2025, Kent Lake Partners LP made a demand for a stockholder list and other books and records of the Company (the “Stockholder List Demand”);

WHEREAS, on July 10, 2025, Kent Lake provided notice to the Company (the “July Notice”) of its intent to (i) nominate three candidates for election to the Board at the 2025 Annual Meeting (ii) submit a shareholder proposal to (x) amend the Company’s governing documents to declassify the Board and provide for the annual election of all directors and (y) amend the Company’s governing documents to adopt a majority voting standard in uncontested director elections; and

WHEREAS, the Company and Kent Lake have determined to come to an agreement with respect to the composition of the Board, the February Notice, the Stockholder List Demand, the July Notice and certain other matters, as provided in this Agreement.

NOW, THEREFORE, in consideration of the foregoing premises and the mutual covenants and agreements contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties, intending to be legally bound hereby, agree as follows:

1.Board Composition and Related Matters.

(a)Kent Lake hereby submits an irrevocable withdrawal of each of the February Notice, the Stockholder List Demand and the July Notice, which withdrawals shall become effective upon the execution and delivery of this Agreement.

(b)The Board and all applicable committees of the Board shall take all necessary actions to seek the approval of the Company’s stockholders at the 2025 Annual Meeting of an amendment to the Amended and Restated Certificate of Incorporation, as amended (and as further amended from time to time, the “Charter”) to declassify the structure of the Board (the “Declassification Proposal”) such that, if approved by the Company’s stockholders in accordance with the Charter, the Company’s Restated Bylaws, as amended (and as further amended from time to time, the “Bylaws”) and the Delaware General Corporation Law, then (i) the Company’s Class III directors with terms expiring at the 2026 annual meeting of stockholders shall stand for election at such meeting and subsequent annual meetings for one-year terms expiring at the next annual meeting of stockholders, (ii) the Company’s Class I directors with terms expiring at the 2027 annual meeting of stockholders (the “2027 Annual Meeting”) shall stand for election at such meeting and subsequent annual meetings for one-year terms expiring at the next annual meeting of stockholders and (iii) the Company’s Class II directors with terms expiring at the 2028 annual meeting of stockholders shall stand for election at such meeting and subsequent annual meetings for one-year terms expiring at the next annual meeting of stockholders, and in each case as to clauses (i), (ii) and (iii), until each such director’s successor is duly elected and qualified. The Board shall recommend in favor, and use its reasonable best efforts to solicit stockholder approval, of the Declassification Proposal at the 2025 Annual Meeting and to have all directors and executive officers of the Company vote all shares beneficially owned by them and over which they have voting control in favor of the Declassification Proposal.

(c)Prior to the 2025 Annual Meeting, the Board shall take all necessary actions to amend the Bylaws to adopt a majority voting standard for uncontested director elections, with a plurality voting standard for contested director elections.

(d)The Company shall provide the director candidate specification that includes the criteria set forth on Exhibit A and is otherwise agreed by the parties to an executive search firm selected by Kent Lake within three (3) Business Days of the date hereof from a list of five (5) executive search firms provided by the Company to Kent Lake, which shall then be promptly retained by the Company (the “Search Firm”). The Search Firm shall provide a list of six (6) potential candidates to each of the Company and Kent Lake, who shall each act reasonably and cooperate in good faith to identify and agree upon one (1) director candidate from such list to be appointed to the Board to serve as a Class I director (the “New Director”) on or prior to December 1, 2025 (the “Target Date”); provided, however, that in the event that the Company and Kent Lake do not mutually agree on the selection of the New Director candidate by the Target Date, the Company shall identify three (3) potential candidates from the Search Firm’s list, and Kent Lake shall select one (1) individual to be appointed to the Board among such three (3) potential candidates. The preceding sentence shall not limit the ability of the Company and Kent Lake to mutually agree on a director candidate to be appointed to the Board, notwithstanding that such candidate is not included in the Search Firm’s list. Notwithstanding the foregoing, if any potential candidate from the Search Firm’s list becomes unavailable or unwilling to serve on the Board, either party may direct the Search Firm to add additional potential candidates to the Search Firm’s list prior to the Company and Kent Lake’s identification of a potential candidate from such list, which, for the avoidance of doubt, shall result in a list of six (6) total potential candidates. Prior, and as a condition, to his or her appointment, the New Director shall comply with the Company’s procedures for new director candidates, including the full completion of a director’s and officer’s questionnaire in the form required by the Company and other reasonable and customary director onboarding documentation, including consent to the Company’s customary background check. The New Director shall (i) qualify as an “independent director” under the applicable rules of the SEC, the rules of any stock exchange on which the Company is traded and the applicable governance policies of the Company, (ii) unless otherwise consented to by the Board, be independent of Kent Lake (for the avoidance of doubt, any partner, officer, employee, Affiliate or Associate of Kent Lake would not be deemed independent of Kent Lake), (iii) serve on no more than a total of three (3) other public company boards of directors, and (iv) meet all other qualifications required for service as a director set forth in the Company’s Charter, Bylaws, Board committee charters, Corporate Governance Guidelines and any similar documents applicable to directors.

2.Voting Commitment. Until the Termination Date (as defined below), Kent Lake shall, or shall cause its Representatives to, (a) appear in person or by proxy at each meeting of the stockholders of the Company (“Stockholder Meeting”) and (b) vote, or deliver consents or consent revocations with respect to, all shares of Common Stock beneficially owned by any of the Kent Lake Parties in accordance with the Board’s recommendations with respect to all proposals submitted to stockholders at such Stockholder Meeting, in each case as the Board’s recommendation is set forth in the definitive proxy statement, consent solicitation statement or revocation solicitation statement filed by the Company in respect of such Stockholder Meeting or as otherwise disclosed by the Company. Notwithstanding the foregoing, in the event that Institutional Stockholder Services Inc. or Glass Lewis & Co., LLC publish voting recommendations that differ from the Board’s recommendation with respect to any proposal (other than a proposal with respect to director elections or removal), Kent Lake shall be permitted to vote, or deliver consents or consent revocations with respect to any shares beneficially owned by any of the Kent Lake Parties in accordance with such recommendations; provided, further, that Kent Lake shall be permitted to vote in its sole discretion with respect to any Extraordinary Transaction (as defined below). Kent Lake shall, or shall cause its Representatives to, take all actions necessary (including by calling back loaned out shares) to ensure that Kent Lake has voting power for each share beneficially owned by any of the Kent Lake Parties on the record date for each Stockholder Meeting.

3.Standstill. Prior to the Termination Date, except as otherwise provided in this Agreement, without the prior written consent of the Board, Kent Lake shall not, and shall cause its Affiliates not to, directly or indirectly:

(a)acquire, offer or seek to acquire, agree to acquire or acquire rights to acquire (except by way of stock dividends or other distributions or offerings made available to holders of voting securities of the Company generally on a pro rata basis or pursuant to an Extraordinary Transaction approved by the Board), whether by purchase, tender offer or exchange offer, through the acquisition of control of another person, by joining a group, through swap or hedging transactions or otherwise, any voting securities of the Company (other than through a broad-based market basket or index) or any voting rights decoupled from the underlying voting securities that would result in the Kent Lake Parties owning, controlling or otherwise having any beneficial or other ownership interest of, in the aggregate, more than 4.9% of the shares of Common Stock outstanding at such time (the “Ownership Cap”);

(b)sell, assign or otherwise transfer or dispose of shares of Common Stock, or any rights decoupled from such shares, beneficially owned by them, other than in open market sale transactions where the identity of the purchaser is not known and in underwritten widely-dispersed public offerings, to any Third Party that, to Kent Lake’s knowledge (after due inquiry, it being understood that such knowledge shall be deemed to exist with respect to any publicly available information, including information in documents filed with the SEC), would result in such Third Party, together with its Affiliates and Associates, owning, controlling or otherwise having any beneficial or other ownership interest of, in the aggregate, more than 4.9% of the shares of Common Stock outstanding at such time or would increase the beneficial ownership interest of any Third Party who, together with its Affiliates and Associates, has a beneficial or other ownership interest of, in the aggregate, more than 4.9% of the shares of Common Stock outstanding at such time;

(c)(i) nominate, recommend for nomination or give notice of an intent to nominate or recommend for nomination a person for election at any Stockholder Meeting at which the Company’s directors are to be elected; (ii) knowingly initiate, encourage, assist or participate in any solicitation of proxies, consents or consent revocations in respect of any election contest or removal contest with respect to the Company’s directors; (iii) submit, initiate, make or be a proponent of any stockholder proposal for consideration at, or bring any other business before, any Stockholder Meeting; (iv) knowingly initiate, encourage, assist or participate in any solicitation of proxies, consents or consent revocations in respect of any stockholder proposal for consideration at, or other business brought before, any Stockholder Meeting; or (v) knowingly initiate, encourage or participate in any “withhold” or similar campaign with respect to any proposal for consideration at, or other business brought before, any Stockholder Meeting; or (vi) call or seek to call, or request the call of, or initiate a consent solicitation or consent revocation solicitation with respect to, alone or in concert with others, any Stockholder Meeting, whether or not such a Stockholder Meeting is permitted by the Charter or the Bylaws, including any “town hall” meeting;

(d)form, join or in any way participate in or with any group or agreement of any kind with respect to any voting securities of the Company, other than any such group or agreement that is with an Affiliate of Kent Lake and such Affiliate agrees to be bound by the terms and conditions of this Agreement as if it were a party hereto and such group or agreement would not result in the Kent Lake Parties exceeding the Ownership Cap;

(e)knowingly seek to advise, influence or encourage any person with respect to the voting of (or execution of a written consent in respect of) or disposition of any securities of the Company (other than any advice, influence or encouragement that is consistent with the Board’s recommendation in connection with such matter);

(f)comment publicly about any director or the Company’s management, policies, strategy, operations, financial results or any transactions involving the Company or any of its subsidiaries;

(g)deposit any voting securities of the Company in any voting trust or subject any Company voting securities to any arrangement or agreement with respect to the voting thereof, other than any such voting trust, arrangement or agreement that (i) is with an Affiliate of Kent Lake that agrees to be bound by the terms and conditions of this Agreement as if it were a party hereto and (ii) would not result in the Kent Lake Parties exceeding the Ownership Cap;

(h)seek publicly, alone or in concert with others, to amend any provision of the Charter, the Bylaws or any of the Company’s Board committee charters, corporate governance guidelines and any similar documents applicable to directors;

(i)demand an inspection of the Company’s books and records;

(j)(i) make any public proposal with respect to or (ii) make any public statement or otherwise knowingly seek to encourage, advise or assist any person in so encouraging or advising with respect to: (A) any change in the composition, number or term of directors serving on the Board or the filling of any vacancies on the Board; (B) any change in the capitalization, dividend policy or share repurchase programs or practices of the Company; (C) any other change in the Company’s management, governance, business, operations, strategy, corporate structure, affairs or policies; (D) any Extraordinary Transaction (other than any public statement regarding how Kent Lake intends to vote its shares of Common Stock with respect to such Extraordinary Transaction and the reasons therefor); (E) causing a class of securities of the Company to be delisted from, or to cease to be authorized to be quoted on, any securities exchange or (F) causing a class of equity securities of the Company to become eligible for termination of registration pursuant to Section 12(g)(4) of the Exchange Act;

(k)initiate, make or in any way knowingly participate in any Extraordinary Transaction or make any proposal, either alone or in concert with others, to the Company or the Board that would reasonably be expected to require a public announcement or disclosure regarding any such matter;

(l)effect or seek to effect, offer or propose to effect, cause or participate in or in any way knowingly assist or facilitate any other person to effect or seek, offer or propose to effect or participate in, or act in any way that would reasonably be expected to result in or require a public announcement or disclosure related to, (i) material acquisition of any assets or businesses of the Company or any of its subsidiaries; (ii) tender offer or exchange offer, merger, acquisition, share exchange or other business combination involving any of the voting securities or any of the material assets or businesses of the Company or any of its subsidiaries; or (iii) recapitalization, restructuring, liquidation, dissolution or other material transaction with respect to the Company or any of its subsidiaries or any material portion of its or their businesses;

(m)enter into any negotiations, agreements or understandings with any Third Party with respect to any of the foregoing, or knowingly advise, assist, encourage or seek to persuade any Third Party to take any action with respect to any of the foregoing, or otherwise take or cause any action inconsistent with any of the foregoing;

(n)publicly make or in any way advance publicly any request or proposal that the Company or the Board amend, modify or waive any provision of this Agreement;

(o)publicly disclose any vote, delivery of consents or consent revocations or failure to deliver consents or consent revocations, as applicable, by Kent Lake against the voting recommendations of the Board in connection with a Stockholder Meeting; or

(p)take any action challenging the validity or enforceability of this Section 3 or this Agreement unless the Company is challenging the validity or enforceability of this Agreement;

provided, however, that the restrictions in this Section 3 shall not prevent Kent Lake from (i) making any factual statement to the extent required by applicable legal process, subpoena or legal requirement from any Governmental Authority with competent jurisdiction over Kent Lake so long as such request did not arise as a result of any action by Kent Lake; (ii) communicating confidentially with the Company so long as such communications would not reasonably be expected to trigger public disclosure obligations for either party; or (iii) tendering shares, receiving payment for shares or otherwise participating in any transaction approved by the Board on the same basis as the other stockholders of the Company. Kent Lake agrees that, prior to the Termination Date, any sale, assignment or other transfer of any shares of Common Stock to any Affiliate shall be void ab initio unless such Affiliate delivers a joinder to this Agreement pursuant to which such Affiliate is subject to all of Kent Lake’s obligations hereunder.

4.Mutual Non-Disparagement.

(a)Until the Termination Date, without the prior written consent of the other party, neither party shall, nor shall it permit any of its Representatives to, directly or indirectly, in any capacity or manner, make, transmit or otherwise communicate any public statement of any kind, whether verbal, in writing, electronically transferred or otherwise, including, but not limited to, any member of the media, that might reasonably be construed to be derogatory or constitute an ad hominem attack on, or otherwise undermine, criticize, disparage or defame the other party or such other party’s Affiliates, subsidiaries, their respective businesses, or their respective current or former directors, officers, or employees. Notwithstanding anything to the contrary contained in this Agreement, a statement or announcement shall only be deemed to be made by the Company or a Representative thereof if made by a member of the Board or senior management team or other designated representative of the Company, in each case authorized to make such statement or announcement on behalf of the Company.

(b)The restrictions in Section 4(a) shall not (i) apply to (A) any compelled testimony or production of information, whether by legal process, subpoena, or as part of a response to a request for information from any Governmental Authority with jurisdiction over the party from whom information is sought, in each case to the extent required, (B) any statement made in connection with any action to enforce this Agreement, (C) any private communications between the parties, or (D) any disclosure that such party reasonably believes, after consultation with outside counsel, to be legally required by applicable law, rules or regulations; or (ii) prohibit any party from reporting what it reasonably believes, after consultation with outside counsel, to be violations of federal law or regulation to any Governmental Authority pursuant to Section 21F of the Exchange Act or Rule 21F promulgated thereunder.

(c)The restrictions in Section 4(a) shall not prevent any party from responding to any public statement made by the other party of the nature described in Section 4(a), if such statement by the other party was made in breach of this Agreement.

5.No Litigation. Prior to the Termination Date, each party hereby covenants and agrees that it shall not, and shall not permit any of its Representatives to, directly or indirectly, alone or in concert with others, encourage, pursue or assist any other person to threaten or initiate any lawsuit, claim or proceeding before any court (each, a “Legal Proceeding”) against the other party or any of its Representatives based on information known or unknown as of the date of this Agreement, except for (a) any Legal Proceeding initiated primarily to remedy a breach of or to enforce this Agreement, (b) counterclaims with respect to any proceeding initiated by or on behalf of one party or its Affiliates against the other party or its Affiliates or (c) any Legal Proceeding with respect to claims of fraud in connection with, arising out of or related to this Agreement; provided, however, that the foregoing shall not prevent any party or any of its Representatives from responding to oral questions, interrogatories, requests for information or documents, subpoenas, civil investigative demands or similar processes (each, a “Legal Requirement”) in connection with any Legal Proceeding if such Legal Proceeding has not been initiated by, on behalf of, or at the direct or indirect suggestion of such party or any of its Representatives; provided, further, that in the event any party or any of its Representatives receives such Legal Requirement, such party shall give prompt written notice of such Legal Requirement to the other party (except where such notice would be legally prohibited or not practicable). Each party represents and warrants that neither it nor any assignee has filed any Legal Proceeding against the other party.

6.Public Statements; SEC Filings.

(a)Within one (1) Business Day following the date of this Agreement, the Company shall issue a press release (the “Press Release”) announcing this Agreement, substantially in the form attached hereto as Exhibit B.

(b)Within two (2) Business Days following the date of this Agreement, the Company shall file with the SEC a Current Report on Form 8-K setting forth a brief description of the terms of this Agreement and appending this Agreement as an exhibit thereto (the “Form 8-K”). The Company shall provide Kent Lake and its Representatives with a reasonable opportunity to review and comment on the Form 8-K prior to its being filed with the SEC and consider in good faith any comments of Kent Lake and its Representatives.

(c)Except for the issuance of the Press Release and the filing of the Form 8-K, neither party shall issue any press release or other public statement (including in any filing required under the Exchange Act) about the subject matter of this Agreement or the other party, except as required by law, Legal Requirement or applicable stock exchange listing rules or with the prior written consent of the other party and otherwise in accordance with this Agreement.

7.Affiliates and Associates. Each party shall cause its controlled Affiliates and Associates and direct its other Representatives to comply with the terms of this Agreement and shall be responsible for any breach or deemed breach of this Agreement by any such controlled Affiliate or Associate or other Representative. A breach of this Agreement by a controlled Affiliate or Associate of a party or a Representative of a party shall be deemed to occur if such controlled Affiliate or Associate or such Representative engages in conduct that would constitute a breach of this Agreement if such controlled Affiliate or Associate or such Representative were a party to this Agreement.

8.Representations and Warranties.

(a)Kent Lake represents and warrants that: (i) it has full power and authority to execute, deliver and carry out the terms and provisions of this Agreement and to consummate the transactions contemplated hereby; (ii) this Agreement has been duly and validly executed and delivered by it, constitutes a valid and binding obligation and agreement of it and is enforceable against it in accordance with its terms, except as enforcement thereof may be limited by applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or similar laws generally affecting the rights of creditors and subject to general equity principles; (iii) the execution of this Agreement, the consummation of the transactions contemplated hereby and the fulfillment of the terms hereof, in each case in accordance with the terms hereof, will not conflict with, or result in a breach or violation of its organizational documents as currently in effect; (iv) the execution, delivery and performance of this Agreement by it does not and will not (A) violate or conflict with any law, rule, regulation, order, judgment or decree applicable to it or (B) result in any breach or violation of or constitute a default under or pursuant to (or an event which with notice or lapse of time or both could constitute such a breach, violation or default), or result in the loss of a material benefit under, or give any right of termination, amendment, acceleration or cancellation of, any organizational document, agreement, contract, commitment, understanding or arrangement to which it is a party or by which it is bound; and (v) as of the date of this Agreement, it beneficially owns an aggregate of 2,050,031 shares of Common Stock and has sole voting authority over all of such shares.

(b)The Company hereby represents and warrants that: (i) it has the power and authority to execute, deliver and carry out the terms and provisions of this Agreement and to consummate the transactions contemplated hereby; (ii) this Agreement has been duly and validly authorized, executed and delivered by the Company, constitutes a valid and binding obligation and agreement of the Company and is enforceable against the Company in accordance with its terms, except as enforcement thereof may be limited by applicable bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or similar laws generally affecting the rights of creditors and subject to general equity principles; (iii) the execution of this Agreement, the consummation of the transactions contemplated hereby and the fulfillment of the terms hereof, in each case in accordance with the terms hereof, will not conflict with, or result in a breach or violation of the organizational documents of the Company as currently in effect and (iv)  the execution, delivery and performance of this Agreement by the Company does not and will not (A) violate or conflict with any law, rule, regulation, order, judgment or decree applicable to the Company or (B) result in any breach or violation of or constitute a default under or pursuant to (or an event which with notice or lapse of time or both could constitute such a breach, violation or default), or result in the loss of a material benefit under, or give any right of termination, amendment, acceleration or cancellation of, any organizational document of the Company or any material agreement, contract, commitment, understanding or arrangement to which the Company is a party or by which it is bound.

9.Termination.

(a)Unless otherwise mutually agreed in writing by each party, this Agreement shall remain in effect until the date that is thirty (30) days prior to the nomination deadline under the Bylaws for the nomination of director candidates for election to the Board at the 2027 Annual Meeting (the “Termination Date”). Notwithstanding anything to the contrary in this Agreement:

(i)the obligations of Kent Lake pursuant to Sections 1, 2, 3, 4 and 6 shall terminate in the event that the Company materially breaches its obligations to Kent Lake pursuant to Sections 1, 4 or 6 or the representations and warranties in Section 8(b) of this Agreement and such breach has not been cured within fifteen (15) days after the Company’s receipt of written notice thereof from Kent Lake, or, if impossible to cure within fifteen (15) days, the Company has not taken substantive action to correct within fifteen (15) days following written notice of such breach from Kent Lake; provided, however, that the obligations of Kent Lake pursuant to Section 4 shall terminate immediately in the event that the Company materially breaches its obligations to Kent Lake under Section 4; provided, further, that the obligations of Kent Lake pursuant to Section 5 shall terminate immediately in the event that the Company materially breaches its obligations to Kent Lake under Section 5; and

(ii)the obligations of the Company to Kent Lake pursuant to Sections 1, 4 and 6 shall terminate in the event that Kent Lake materially breaches its obligations in Sections 1, 2, 3, 4 or 6 or the representations and warranties in Section 8(a), and such breach has not been cured within fifteen (15) days after Kent Lake’s receipt of written notice thereof from the Company, or, if impossible to cure within fifteen (15) days, Kent Lake has not taken substantive action to correct within fifteen (15) days following written notice of such breach from the Company; provided, however, that the obligations of the Company pursuant to Section 4 shall terminate immediately in the event that Kent Lake materially breaches its obligations to the Company under Section 4; provided, further, that the obligations of the Company pursuant to Section 5 shall terminate immediately in the event that Kent Lake materially breaches its obligations to the Company under Section 5.

(b)If this Agreement is terminated in accordance with this Section 9, this Agreement shall forthwith become null and void, but no termination shall relieve either party from liability for any breach of this Agreement prior to such termination. Notwithstanding the foregoing, Sections 11, 12, 13 and 15 shall survive the termination of this Agreement.

10.Expenses. The Company shall reimburse Kent Lake for all reasonable and documented out-of-pocket costs, fees and expenses (including attorneys’ fees and other legal expenses) incurred by Kent Lake in connection with its engagement with the Company since January 10, 2025 and the negotiation and execution of this Agreement and related filings; provided, however, that such reimbursement shall not exceed $950,000 in the aggregate.

11.Notices. All notices, demands and other communications to be given or delivered under or by reason of the provisions of this Agreement shall be in writing and shall be deemed to have been given (a) when delivered by hand, with written confirmation of receipt; (b) upon sending, if sent by electronic mail to the electronic mail addresses below, with confirmation of receipt from the receiving party by electronic mail; (c) one Business Day after being sent by a nationally recognized overnight courier to the addresses

set forth below; or (d) when actually delivered if sent by any other method that results in delivery, with written confirmation of receipt:

12.Governing Law; Jurisdiction; Jury Waiver. This Agreement, and any disputes arising out of or related to this Agreement (whether for breach of contract, tortious conduct or otherwise), shall be governed by, and construed in accordance with, the laws of the State of Delaware, without giving effect to any choice or conflict of law provision or rule that would cause the application of laws of any jurisdiction other than those of the State of Delaware. The parties agree that exclusive jurisdiction and venue for any Legal Proceeding arising out of or related to this Agreement shall exclusively lie in the Court of Chancery of the State of Delaware or, if such Court does not have subject matter jurisdiction, the Superior Court of the State of Delaware or, if jurisdiction is vested exclusively in the federal courts of the United States, the federal courts sitting in the State of Delaware and any appellate court from any such state or federal court. Each party waives any objection it may now or hereafter have to the laying of venue of any such Legal Proceeding and irrevocably submits to personal jurisdiction in any such court in any such Legal Proceeding and hereby further irrevocably and unconditionally waives and agrees not to plead or claim in any court that any such Legal Proceeding brought in any such court has been brought in any inconvenient forum. Each party consents to accept service of process in any such Legal Proceeding by service of a copy thereof delivered to it by certified or registered mail, postage prepaid, return receipt requested, addressed to it at the address set forth in Section 11. Nothing contained herein shall be deemed to affect the right of any party to serve process in any manner permitted by law. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATED TO THIS AGREEMENT.

13.Specific Performance. Each party to this Agreement acknowledges and agrees that the other party would be irreparably injured by an actual breach of this Agreement by the first-mentioned party or its Representatives and that monetary remedies would be inadequate to protect either party against any actual or threatened breach or continuation of any breach of this Agreement. Without prejudice to any other rights and remedies otherwise available to the parties under this Agreement, each party shall be entitled to equitable relief by way of injunction or otherwise and specific performance of the provisions hereof upon satisfying the requirements to obtain such relief, without the necessity of posting a bond or other security, if the other party or any of its Representatives breaches or threatens to breach any provision of this Agreement. Such remedy shall not be deemed to be the exclusive remedy for a breach of this Agreement but shall be in addition to all other remedies available at law or equity to the non-breaching party.

14.Certain Definitions and Interpretations. As used in this Agreement: (a) the terms “Affiliate” and “Associate” (and any plurals thereof) have the meanings ascribed to such terms under Rule 12b-2 promulgated by the SEC under the Exchange Act and shall include all persons that at any time prior to the Termination Date become Affiliates or Associates of any applicable person or entity referred to in this Agreement; provided, however, that, for purposes of this Agreement, Kent Lake shall not be an Affiliate or Associate of the Company, and the Company shall not be an Affiliate or Associate of Kent Lake; (b) the terms “beneficial ownership,” “group,” “proxy” and “solicitation” (and any plurals thereof) have the meanings ascribed to such terms under the Exchange Act and the rules and regulations promulgated thereunder; provided, however, that the meaning of “solicitation” shall be without regard to the exclusions set forth in Rule 14a-1(l)(2)(iv) and Rule 14a-2 under the Exchange Act; (c) the term “Business Day” means any day that is not a Saturday, Sunday or other day on which commercial banks in the State of New York are authorized or obligated to be closed by applicable law; (d) the term “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder; (e) the term “Extraordinary Transaction” means any tender offer, exchange offer, merger, consolidation, acquisition, business combination, sale, recapitalization, restructuring or other similar corporate transaction with a Third Party that, in each case, that results in a change in control of the Company or the sale of all or substantially all of its assets; (f) the term “Governmental Authority” means any federal, state, local, municipal, or foreign government and any political subdivision thereof, any authority, bureau, commission, department, board, official, or other instrumentality of such government or political subdivision, any self-regulatory organization or other non-government regulatory authority or quasi-governmental authority (to the extent that the rules, regulations or orders of such organization or authority have the force of law), including, but not limited to, the SEC and its staff, and any court of competent jurisdiction; (g) the term “person” means any individual, corporation (including not-for-profit), general or limited partnership, limited liability or unlimited liability company, joint venture, estate, trust, associate, organization or other entity of any kind or nature; (h) the term “Representatives” with respect to a person means (i) such person’s Affiliates and Associates and (ii) such person’s and such person’s Affiliates’ and Associates’ respective directors, officers, employees, partners, members, managers, consultants, legal or other advisors, agents and other representatives acting in a capacity on behalf of, in concert with or at the direction of such person or its Affiliates or Associates; (i) the term “SEC” means the U.S. Securities and Exchange Commission; (j) the term “Shareholder Meeting” means each annual or special meeting of stockholders of the Company, or any action by written consent of the Company’s stockholders in lieu thereof, and any adjournment, postponement, rescheduling or continuation thereof and (k) the term “Third Party” refers to any person other than the Company, Kent Lake and any of their respective Affiliates, Associates or representatives in their capacities as such. In this Agreement, (i) the word “including” (in its various forms) means “including, without limitation;” (ii) the words “hereunder,” “hereof,” “hereto” and words of similar import are references in this Agreement as a whole and not to any particular provision of this Agreement; (iii) the word “or” is not exclusive; (iv) references to “Sections” in this Agreement are references to Sections of this Agreement unless otherwise indicated and (v) whenever the context requires, the masculine gender shall include the feminine and neuter genders.

15.Miscellaneous.

(a)This Agreement, including all exhibits hereto, contains the entire agreement between the parties and supersedes all other prior agreements and understandings, both written and oral, between the parties with respect to the subject matter hereof.

(b)This Agreement is solely for the benefit of the parties and is not enforceable by any other persons.

(c)This Agreement shall not be assignable by operation of law or otherwise by a party without the consent of the other party. Any purported assignment without such consent is void ab initio. Subject to the foregoing sentence, this Agreement shall be binding upon, inure to the benefit of and be enforceable by and against the permitted successors and assigns of each party.

(d)Neither the failure nor any delay by a party in exercising any right, power or privilege under this Agreement shall operate as a waiver thereof, nor shall any single or partial exercise thereof preclude any other or further exercise thereof or the exercise of any right, power or privilege hereunder.

(e)If any term, provision, covenant or restriction of this Agreement is held by a court of competent jurisdiction to be invalid, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions of this Agreement shall remain in full force and effect and shall in no way be affected, impaired or invalidated. It is hereby stipulated and declared to be the intention of the parties that the parties would have executed the remaining terms, provisions, covenants and restrictions without including any of such which may be hereafter declared invalid, void or unenforceable. In addition, the parties agree to use their reasonable best efforts to agree upon and substitute a valid and enforceable term, provision, covenant or restriction for any of such that is held invalid, void or unenforceable by a court of competent jurisdiction.

(f)Any amendment or modification of the terms and conditions set forth herein or any waiver of such terms and conditions must be agreed to in a writing signed by each party.

(g)This Agreement may be executed in one or more textually identical counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same agreement. Signatures to this Agreement transmitted by facsimile transmission, by electronic mail in “portable document format” (“.pdf”) form, or by any other electronic means intended to preserve the original graphic and pictorial appearance of a document, shall have the same effect as physical delivery of the paper document bearing the original signature.

(h)Each party acknowledges that it has been represented by counsel of its choice throughout all negotiations that have preceded the execution of this Agreement and that it has executed this Agreement with the advice of such counsel.

(i)The headings set forth in this Agreement are for convenience of reference purposes only and will not affect or be deemed to affect in any way the meaning or interpretation of this Agreement or any term or provision of this Agreement.

[Signature Page Follows]

IN WITNESS WHEREOF, each of the parties has executed this Agreement, or caused the same to be executed by its duly authorized representative, as of the date first above written.

COMPANY:

By: /s/ Masoud Toloue

Name: Masoud Toloue

Title: Chief Executive Officer

KENT LAKE:

Company and Kent Lake Capital Agree to Identify New Independent Board Member

Company will Seek Shareholder Approval to De-Classify its Board of Directors

Board of Directors to Adopt Majority Voting Standard in Uncontested Director Elections

BILLERICA, Mass.--(BUSINESS WIRE)--Aug. 4, 2025-- Quanterix Corporation (“Quanterix” or the “Company”) (NASDAQ: QTRX), a company fueling scientific discovery through ultrasensitive biomarker detection, today announced that it has entered into a cooperation agreement (the “Agreement”) with Kent Lake Partners LP (together with its affiliates, “Kent Lake”).

The Company has committed to appointing a new independent director by December 1, 2025. The new director will be identified through a comprehensive search process in which both Kent Lake and the Board of Directors (the “Board”) shall have meaningful participation. In addition, the Company will seek approval at the 2025 Annual Meeting of Stockholders (the “Annual Meeting”) to declassify its Board and will amend its bylaws to adopt a majority voting standard for uncontested director elections

Under the terms of the Agreement, Kent Lake has agreed to withdraw its director nominations and shareholder proposals previously submitted in connection with the Annual Meeting and will support the Board’s candidates. In addition, Kent Lake has agreed to customary standstill and voting commitments until thirty days prior to the nomination deadline for Quanterix’s 2027 Annual Meeting.

“We are pleased to have reached a constructive agreement with Kent Lake that will allow the Board and management team to remain fully focused on executing the Company’s strategy, navigating the dynamic industry environment and maximizing the benefits of the Akoya transaction,” said William P. Donnelly, Chairman of the Quanterix Board. “We look forward to working with Kent Lake to identify a new director who can help us unlock the Company’s full potential and advance our goal of changing the way disease is detected, understood and treated.”

Benjamin Natter, Managing Member of Kent Lake, said, “We are confident that the addition of a new independent director and governance enhancements will benefit the Company and its stockholders and help position Quanterix for continued success.”

The full cooperation agreement between Quanterix and Kent Lake will be filed with the U.S. Securities and Exchange Commission on a Current Report on Form 8-K.

Quanterix is a global leader in ultra-sensitive biomarker detection, enabling breakthroughs in disease research, diagnostics, and drug development. Its proprietary Simoa® technology delivers industry-leading sensitivity, allowing researchers to detect and quantify biomarkers in blood and other fluids at concentrations far below traditional limits. With more than 3,400 peer-reviewed publications, Quanterix has been a trusted partner to the scientific community for nearly two decades. In 2025, Quanterix acquired Akoya Biosciences, The Spatial Biology Company®, adding multiplexed tissue imaging with single-cell resolution to its portfolio and 1,396 installed instruments. Together, the combined company offers a uniquely integrated platform that connects biology across blood and tissue—advancing precision medicine from discovery to diagnostics. Learn more at www.quanterix.com.

The Company intends to file a definitive proxy statement on Schedule 14A, an accompanying WHITE proxy card and other relevant documents with the SEC in connection with the solicitation of proxies from the Company’s stockholders for the Company’s Annual Meeting. STOCKHOLDERS OF THE COMPANY ARE STRONGLY ENCOURAGED TO READ THE COMPANY’S DEFINITIVE PROXY STATEMENT (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS THERETO) AND ALL OTHER DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION.

Stockholders may obtain a copy of the definitive proxy statement, an accompanying WHITE proxy card, any amendments or supplements to the definitive proxy statement and other documents filed by the Company with the SEC at no charge at the SEC’s website at www.sec.gov. Copies will also be available at no charge on the Company’s investor relations website at ir.quanterix.com or by contacting the Company’s Investor Relations department at https://ir.quanterix.com/investor-resources/contact-ir. as soon as reasonably practicable after such materials are electronically filed with, or furnished to, the SEC.

The Company, its directors and certain of its executive officers are participants in the solicitation of proxies from the Company’s shareholders in connection with matters to be considered at the Annual Meeting. Information regarding the direct and indirect interests, by security holdings or otherwise, of the Company’s directors and executive officers is included in the sections entitled “Security Ownership of Certain Beneficial Owners and Management,” “Management and Corporate Governance” and “Executive Officer and Director Compensation” of the Company’s Proxy Statement on Schedule 14A for its 2024 annual meeting of shareholders, filed with the SEC on April 15, 2024 (available here); in the sections entitled “Directors, Executive Officers and Corporate Governance,” “Executive Compensation—Executive Officer and Director Compensation Tables” and “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters—Security Ownership of Certain Beneficial Owners and Management” of the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on March 17, 2025 (available here) (as amended on April 30, 2025 (available here)), and in the Company’s Current Report on Form 8-K filed with the SEC on July 8, 2025 (available here). Changes to the direct or indirect interests of the Company’s directors and executive officers are set forth in Initial Statements of Beneficial Ownership filed with the SEC on May 2, 2025, May 19, 2025, June 3, 2025, June 10, 2025, June 17, 2025, July 7, 2025, July 17 for Mr. Masoud (available here, here, here, here, here, here and here); on May 19, 2025, June 17, 2025 and July 17, 2025 for Ms. Vandana (available here, here and here); on June 9, 2025 and July 2, 2025 for Mr. Donnelly (available here and here); on June 9, 2025, June 13, 2025 and July 2, 2025 for Mr. Walt (available here, here and here); on July 2, 2025 for Mr. Meister (available here); on July 9, 2025 and July 10, 2025 for Mr. Mendel (available here and here); and on July 9, 2025 and July 10, 2025 for Ms. Lai-Goldman (available here and here). These documents are available free of charge as described above. Updated information regarding the identities of potential participants and their direct or indirect interests, by security holdings or otherwise, in the Company will be set forth in the definitive proxy statement for the Annual Meeting and other relevant documents to be filed with the SEC, if and when they become available.

Statements included in this press release which are not historical in nature or do not relate to current facts are intended to be, and are hereby identified as, forward-looking statements for purposes of the safe harbor provided by Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements include, among other things, statements about Quanterix’s future business outlook, operations, strategy and financial performance. Words and phrases such as “may,” “approximately,” “continue,” “should,” “expects,” “projects,” “anticipates,” “is likely,” “look ahead,” “look forward,” “believes,” “will,” “intends,” “estimates,” “strategy,” “plan,” “could,” “potential,” “possible” and variations of such words and similar expressions are intended to identify such forward-looking statements. Forward-looking statements are subject to certain risks and uncertainties that are difficult to predict with regard to, among other things, timing, extent, likelihood and degree of occurrence, which could cause actual results to differ materially from anticipated results. Such risks and uncertainties include, among others, the following possibilities with respect to Quanterix’s future business, operations, strategy and financial performance: risks related to the impact of recent U.S. government policies, including reductions in federal research funding and increased tariffs; risks that we may not realize the expected benefits of our cost reduction actions; risks associated with the anticipated timing for launch of, and features of, Quanterix’s next-generation instrument, Simoa ONE; risks that Quanterix may fail to realize the anticipated benefits and synergies of its recent acquisition of Emission, Inc.; that Quanterix’s estimates regarding expenses, future revenues, capital requirements, and needs for additional financing could be incorrect; risks related to the restatement of Quanterix’s consolidated financial statements, including risks of increased costs and the increased possibility of legal proceedings and regulatory inquiries, sanctions, or investigation; risks related to Quanterix’s ability to maintain effective internal control over financial reporting and disclosure controls and procedures, including its ability to remediate existing material weaknesses in its internal control over financial reporting and the timing of any such remediation; Quanterix’s ability to realize the intended benefits of its assay redevelopment program; and Quanterix’s ability to retain and expand its customer base and achieve sufficient market acceptance of its products.

Additional factors that could cause results to differ materially from those described above can be found in the Proxy Statement/Prospectus, and in periodic reports filed by Quanterix and Akoya with the SEC, including the “Risk Factors” sections contained therein, which are available on the SEC’s website at www.sec.gov.

All forward-looking statements, expressed or implied, included in this press release are expressly qualified in their entirety by the cautionary statements contained or referred to herein. If one or more events related to these or other risks or uncertainties materialize, or if Quanterix’s underlying assumptions prove to be incorrect, actual results may differ materially from what Quanterix anticipates. Quanterix cautions readers not to place undue reliance on any such forward-looking statements, which speak only as of the date they are made and are based on information available at that time. Quanterix does not assume any obligation to update or otherwise revise any forward-looking statements to reflect circumstances or events that occur after the date the forward-looking statements were made or to reflect the occurrence of unanticipated events except as required by federal securities laws.

Media Contact:

Marissa Klaassen

(781) 913.8036

media@quanterix.com

Joshua Young

(508) 846-3327

ir@quanterix.com