# EDGAR Filing Document

**Accession Number:** 0001503274
**File Stem:** 0001104659-25-067446
**Filing Date:** 2025-7
**Character Count:** 34452
**Document Hash:** d578b5be2f60069d184338a4e0aa05d7
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-067446.hdr.sgml**: 20250711

**ACCESSION NUMBER**: 0001104659-25-067446

**CONFORMED SUBMISSION TYPE**: S-8 POS

**PUBLIC DOCUMENT COUNT**: 5

**FILED AS OF DATE**: 20250711

**DATE AS OF CHANGE**: 20250711

**EFFECTIVENESS DATE**: 20250711

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Quanterix Corp
- **CENTRAL INDEX KEY:** 0001503274
- **STANDARD INDUSTRIAL CLASSIFICATION:** LABORATORY ANALYTICAL INSTRUMENTS [3826]
- **ORGANIZATION NAME:** 08 Industrial Applications and Services
- **EIN:** 208957988
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-8 POS
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-284932
- **FILM NUMBER:** 251119574

**BUSINESS ADDRESS:**
- **STREET 1:** 900 MIDDLESEX TURNPIKE
- **CITY:** BILLERICA
- **STATE:** MA
- **ZIP:** 01821
- **BUSINESS PHONE:** 617-301-9400

**MAIL ADDRESS:**
- **STREET 1:** 900 MIDDLESEX TURNPIKE
- **CITY:** BILLERICA
- **STATE:** MA
- **ZIP:** 01821

**As filed with the Securities and Exchange Commission on July 11, 2025**

**Registration No. 333-284932**

**UNITED STATES** 

**SECURITIES AND EXCHANGE COMMISSION** 

**Washington, D.C. 20549**

**POST-EFFECTIVE AMENDMENT NO. 3** 

**ON FORM S-8 TO** 

**FORM S-4 REGISTRATION STATEMENT** 

**UNDER THE SECURITIES ACT OF 1933**

**Quanterix Corporation** 

(Exact name of registrant as specified in its charter)

---

| | |
|:---|:---|
| **Delaware** | **20-8957988** |
| (State or other jurisdiction of incorporation or<br> organization) | (I.R.S. Employer Identification No.) |
| **900 Middlesex Turnpike** |  |
| **Billerica, MA** | **01821** |
| (Address of Principal Executive Offices) | (Zip Code) |

---

**Akoya Biosciences, Inc. 2021 Equity Incentive Plan** 

**Akoya Biosciences, Inc. 2015 Equity Incentive Plan** 

(Full title of the plans)

**Masoud Toloue, Ph.D.** 

**President and Chief Executive Officer** 

**Quanterix Corporation** 

**900 Middlesex Turnpike** 

**Billerica, MA 01821** 

**(617) 301-9400**<br> (Name, address and telephone number, including area code, of agent for service)

**Copies to:**

---

| | |
|:---|:---|
| **Kerry S. Burke**<br> **Catherine Dargan**<br> **Kyle Rabe<br> Covington & Burling LLP**<br> **One CityCenter<br> 850 Tenth Street, N.W.<br> Washington, D.C. 20001**<br> **(202) 662-6000** | **Laurie Churchill<br> General Counsel<br> Quanterix Corporation<br> 900 Middlesex Turnpike<br> Billerica, MA 01821<br> (617) 301-9400** |

---

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer ◻ Accelerated filer ⌧ <br> Non-accelerated filer ◻ Smaller reporting company ◻ <br> Emerging growth company ◻

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 7(a)(2)(B) of the Securities Act. ◻

**EXPLANATORY NOTE**

Quanterix Corporation ("Quanterix" or the "Registrant") hereby further amends its Registration Statement on Form S-4 (File No. 333-284932), which was previously amended by Post-Effective Amendments Nos. 1 and 2, filed on May 21, 2025 and June 6, 2025, respectively, and was declared effective by the Securities and Exchange Commission (the "Commission") on June 12, 2025 (as so amended, the "Form S-4"), by filing this Post-Effective Amendment No. 3 on Form S-8 (this "Post-Effective Amendment" and, together with the Form S-4, the "Registration Statement"). Quanterix filed the Form S-4 in connection with the merger (the "Merger") of Wellfleet Merger Sub, Inc., a wholly owned subsidiary of Quanterix ("Merger Sub"), with and into Akoya Biosciences, Inc. ("Akoya"), with Akoya surviving as a wholly owned subsidiary of Quanterix in the Merger. At the effective time of the Merger (the "Effective Time"), each share of common stock of Akoya ("Akoya Common Stock"), $0.00001 par value per share, outstanding immediately prior to the Effective Time was converted into the right to receive (a) 0.1470 of a share of the common stock of Quanterix ("Quanterix Common Stock"), par value $0.001 per share (the "Per Share Stock Consideration") and, if applicable, cash in lieu of fractional shares, and (b) $0.37 in cash, without interest (the "Per Share Cash Consideration" and, together with the Per Share Stock Consideration, the "Per Share Merger Consideration"). In connection with the Merger, Quanterix assumed, subject to certain adjustments, the Akoya Biosciences, Inc. 2015 Equity Incentive Plan, as amended, and the Akoya Biosciences, Inc. 2021 Equity Incentive Plan (together, the "Assumed Plans").

In connection with the filing of the Form S-4, Quanterix registered 8,357,169 shares of Quanterix Common Stock. The number of shares represents those shares of Quanterix Common Stock that were expected to be distributed to the holders of Akoya Common Stock at the time of the Merger and the maximum number of shares issued or issuable under the Assumed Plans, including with respect to Rollover RSUs (as defined below). Pursuant to the terms of the Merger Agreement, at the Effective Time:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;· Each restricted stock unit in respect of shares of Akoya Common Stock (each,
an "Akoya RSU") that was outstanding and unvested (each, a "Rollover RSU") was automatically converted into the
right to receive the Per Share Merger Consideration upon vesting. Each Rollover RSU otherwise remained subject to the same terms and conditions,
including vesting, as were applicable immediately prior to the Effective Time.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;· Each Akoya RSU that was outstanding and vested immediately prior to the Effective
Time received the Per Share Merger Consideration.

This Registration Statement relates only to the 253,181 shares of Quanterix Common Stock that were previously registered on the Form S-4, representing the maximum number of shares of Quanterix Common Stock in respect of the Rollover RSUs issuable pursuant to the Assumed Plans. All filing fees payable in connection with the issuance of these shares were previously paid in connection with the filing of the Form S-4. Pursuant to Rule 416(a) promulgated under the Securities Act of 1933, as amended (the "Securities Act"), this Registration Statement shall also cover any additional shares of Quanterix Common Stock that become issuable by reason of any stock dividend, stock split, recapitalization or other similar transaction that results in an increase in the number of outstanding shares of Quanterix Common Stock.

**PART I**

**INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS**

**Item 1. Plan Information.**\*

**Item 2. Registrant Information and Employee Plan Annual Information.**\*

\* In accordance with Rule 428 under the Securities Act and the Note to Part I of Form S-8, the information required by this Part I of Form S-8 is not and will not be filed with the Commission either as part of this Registration Statement or as prospectuses or prospectus supplements pursuant to Rule 424 under the Securities Act.

**PART II** 

**INFORMATION REQUIRED IN THE REGISTRATION STATEMENT**

**Item 3. Incorporation of Certain Documents by Reference.**

The Registrant is subject to the informational and reporting requirements of Sections 13(a), 14 and 15(d) of the Securities Exchange Act of 1934 (the "Exchange Act") and in accordance therewith files reports, proxy statements and other information with the Commission. The following documents, which are on file with the Commission, are incorporated in this Registration Statement by reference:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) Quanterix's [Annual Report on Form 10-K](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000031/qtrx-20241231.htm) for the fiscal year ended December 31, 2024, filed with the Commission on March 17, 2025, as Amended by [Amendment No. 1](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000110465925042597/qtrx-20250425x10ka.htm), filed with the Commission on April 30, 2025 (File No. 001-38319);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) Quanterix's [Quarterly Report on Form 10-Q](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000054/qtrx-20250331.htm) for the period ended March 31, 2025, filed with the Commission on May 12, 2025 (File No. 001-38319);

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c) Quanterix's Current Reports on Form 8-K, filed with the Commission on[January 8, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000001/qtrx-20250108.htm), [January 10, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000002/qtrx-20250109.htm), [January 31, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000010/qtrx-20250127.htm), [February 25, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000017/qtrx-20250224.htm), [March 28, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000038/qtrx-20250327.htm), [April 4, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000042/qtrx-20250402.htm), [April 29, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000110465925040749/tm2513227d1_8k.htm), [May 12, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000051/qtrx-20250507.htm), [May 14, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000056/qtrx-20250509.htm), [July 1, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/0001503274/000150327425000063/qtrx-20250626.htm) and [July 8, 2025](https://www.sec.gov/ix?doc=/Archives/edgar/data/1503274/000150327425000065/qtrx-20250708.htm) (except for any portions of such Current Reports on Form 8-K furnished pursuant to Item 2.02 and/or Item 7.01 thereof and any corresponding exhibits thereto not filed with the Commission) (File No. 001-38319); and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(d) The description of Quanterix Common Stock filed as [Exhibit 4.1](https://www.sec.gov/Archives/edgar/data/1503274/000155837020002676/qtrx-20191231ex41d7e8c08.htm) to Quanterix's Annual Report on Form 10-K for the fiscal year ended December 31, 2019, filed with the Commission on March 13, 2020 (File No. 001-38319).

In addition, subsequent to the date of this Registration Statement and prior to the filing of a post-effective amendment hereto that indicates that all securities offered hereunder have been sold or deregisters all securities then remaining unsold, all reports and other documents filed by the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act shall be deemed to be incorporated by reference herein and to be a part hereof from the date of filing of such documents; provided, however, that no information furnished (but not filed) under Item 2.02 or Item 7.01 of any Current Report on Form 8-K and any corresponding exhibits thereto not filed with the Commission shall be incorporated by reference except to the extent specified in such Current Report on Form 8-K.

Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for the purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed document that also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

**Item 4. Description of Securities.**

Not applicable.

**Item 5. Interests of Named Experts and Counsel.**

The validity of the issuance of the shares of Quanterix Common Stock registered under this Registration Statement has been passed upon for the Registrant by Covington & Burling LLP.

**Item 6. Indemnification of Directors and Officers.**

Section 145(a) of the Delaware General Corporation Law (the "DGCL") provides, in general, that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation), because he or she is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with such action, suit or proceeding, if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful.

Section 145(b) of the DGCL provides, in general, that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor because the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees) actually and reasonably incurred by the person in connection with the defense or settlement of such action or suit if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made with respect to any claim, issue or matter as to which he or she shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or other adjudicating court determines that, despite the adjudication of liability but in view of all of the circumstances of the case, he or she is fairly and reasonably entitled to indemnity for such expenses that the Court of Chancery or other adjudicating court shall deem proper.

Section 145(g) of the DGCL provides, in general, that a corporation may purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against any liability asserted against such person and incurred by such person in any such capacity, or arising out of his or her status as such, whether or not the corporation would have the power to indemnify the person against such liability under Section 145 of the DGCL.

The Registrant's restated certificate of incorporation (the "Charter") provides that no director of the Registrant shall be personally liable to the Registrant or its stockholders for monetary damages for any breach of fiduciary duty as a director, except for liability (1) for any breach of the director's duty of loyalty to the Registrant or its stockholders, (2) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (3) in respect of unlawful dividend payments or stock redemptions or repurchases, or (4) for any transaction from which the director derived an improper personal benefit. In addition, the Charter provides that if the DGCL is amended to authorize the further elimination or limitation of the liability of directors, then the liability of a director of the Registrant shall be eliminated or limited to the fullest extent permitted by the DGCL, as so amended.

The Charter further provides that any repeal or modification of such article by the Registrant's stockholders or amendment to the DGCL will not adversely affect any right or protection existing at the time of such repeal or modification with respect to any acts or omissions occurring before such repeal or modification of a director serving at the time of such repeal or modification.

The Registrant's restated bylaws (the "Bylaws"), provide that the Registrant will indemnify each of its directors and officers and, in the discretion of its board of directors, certain employees, to the fullest extent permitted by the DGCL as the same may be amended (except that in the case of amendment, only to the extent that the amendment permits the Registrant to provide broader indemnification rights than the DGCL permitted it to provide prior to such the amendment) against any and all expenses, judgments, penalties, fines and amounts reasonably paid in settlement that are incurred by the director, officer or such employee or on the director's, officer's or employee's behalf in connection with any threatened, pending or completed proceeding or any claim, issue or matter therein, to which he or she is or is threatened to be made a party because he or she is or was serving as a director, officer or employee of the Registrant, or at the Registrant's request as a director, partner, trustee, officer, employee or agent of another corporation, partnership, joint venture, trust, employee benefit plan or other enterprise, if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the Registrant and, with respect to any criminal proceeding, had no reasonable cause to believe his or her conduct was unlawful. The Bylaws further provide for the advancement of expenses to each of the directors and officers and, in the discretion of the board of directors, to certain employees and agents.

In addition, the Bylaws provide that the right of each of the Registrant's directors and officers to indemnification and advancement of expenses shall be a contract right and shall not be exclusive of any other right now possessed or hereafter acquired under any statute, provision of the Charter or Bylaws, agreement, vote of stockholders or otherwise. Furthermore, the Bylaws authorize the Registrant to provide insurance for its directors, officers, employees and agents against any liability, whether or not it would have the power to indemnify such person against such liability under the DGCL or the provisions of our Bylaws.

The Registrant has also entered into indemnification agreements with each of its directors and executive officers. These agreements provide that the Registrant will indemnify each of its directors and such officers to the fullest extent permitted by law and the Charter and Bylaws.

The Registrant also maintains a general liability insurance policy, which covers certain liabilities of its directors and officers arising out of claims based on acts or omissions in their capacities as directors or officers.

The foregoing discussion of the Charter, Bylaws, indemnification agreements and the DGCL is not intended to be exhaustive and is qualified in its entirety by such Charter, Bylaws, indemnification agreements or law.

**Item 7. Exemption from Registration Claimed.**

Not Applicable.

**Item 8. Exhibits.**

---

| | |
|:---|:---|
| **Exhibit <br> No.** | **Description** |
| [3.1](https://www.sec.gov/Archives/edgar/data/1503274/000110465917073618/a17-28479_1ex3d1.htm) | [Amended and Restated Certificate of Incorporation of the Registrant (incorporated herein by reference to Exhibit 3.1 of the Registrant's Current Report on Form 8-K filed on December 15, 2017).](https://www.sec.gov/Archives/edgar/data/1503274/000110465917073618/a17-28479_1ex3d1.htm) |
| [3.2](https://www.sec.gov/Archives/edgar/data/1503274/000155837023013792/tmb-20230630xex3d2.htm) | [Restated Bylaws of the Registrant (incorporated herein by reference to Exhibit 3.2 of the Registrant's Quarterly Report on Form 10-Q filed on August 8, 2023).](https://www.sec.gov/Archives/edgar/data/1503274/000155837023013792/tmb-20230630xex3d2.htm) |
| [4.1](https://www.sec.gov/Archives/edgar/data/1503274/000104746917006947/a2233678zex-4_1.htm) | [Form of Common Stock Certificate of the Registrant (incorporated herein by reference to Exhibit 4.1 of the Registrant's Registration Statement on Form S-1 filed on November 9, 2017).](https://www.sec.gov/Archives/edgar/data/1503274/000104746917006947/a2233678zex-4_1.htm) |
| [5.1\*](tm2520205d1_ex5-1.htm) | [Opinion of Covington and Burling LLP.](tm2520205d1_ex5-1.htm) |
| [23.1\*](tm2520205d1_ex5-1.htm) | [Consent of Covington and Burling LLP (included in Exhibit 5.1).](tm2520205d1_ex5-1.htm) |
| [23.2\*](tm2520205d1_ex23-2.htm) | [Consent of Ernst & Young LLP.](tm2520205d1_ex23-2.htm) |
| [23.3\*](tm2520205d1_ex23-3.htm) | [Consent of RSM US LLP, independent registered public accounting firm to Akoya Biosciences, Inc.](tm2520205d1_ex23-3.htm) |
| [24.1\*](#poa_001) | [Power of Attorney (included on the signature page of this Registration Statement).](#poa_001) |
| [99.1](https://www.sec.gov/Archives/edgar/data/1711933/000110465921049062/tm212065d11_ex10-2.htm) | [Akoya Biosciences, Inc. 2021 Equity Incentive Plan (incorporated herein by reference to Exhibit 10.2 to the Form S-1 of Akoya Biosciences, Inc. filed on March 26, 2021).](https://www.sec.gov/Archives/edgar/data/1711933/000110465921049062/tm212065d11_ex10-2.htm) |
| [99.2](https://www.sec.gov/Archives/edgar/data/1711933/000110465921042408/tm212065d6_ex10-1.htm) | [Akoya Biosciences, Inc. 2015 Equity Incentive Plan (incorporated herein by reference to Exhibit 10.1 to the Form S-1 of Akoya Biosciences, Inc. filed on March 26, 2021).](https://www.sec.gov/Archives/edgar/data/1711933/000110465921042408/tm212065d6_ex10-1.htm) |
| [99.3](https://www.sec.gov/Archives/edgar/data/1711933/000110465925024422/tm259213d1_ex99-4.htm) | [Form of Restricted Stock Unit Award Grant Notice and Restricted Stock Unit Award Agreement for 2021 Equity Incentive Plan (incorporated herein by reference to Exhibit 99.4 to the Form S-8 of Akoya Biosciences, Inc. filed on March 17, 2025).](https://www.sec.gov/Archives/edgar/data/1711933/000110465925024422/tm259213d1_ex99-4.htm) |

---

\* Filed herewith.

**Item 9. Undertakings.**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a) The undersigned Registrant hereby undertakes:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Filing Fee" table in the effective Registration Statement;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement;

*Provided, however*, that paragraphs (1)(i) and (1)(ii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the Registration Statement.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial *bona fide* offering thereof.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b) The undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 that is incorporated by reference in this Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial *bona fide* offering thereof.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the indemnification provisions summarized in Item 6, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

**SIGNATURES**

Pursuant to the requirements of the Securities Act, the registrant has duly caused this Post-Effective Amendment No. 3 to the Registration Statement on Form S-4 to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of Billerica, Commonwealth of Massachusetts on July 11, 2025.

**QUANTERIX CORPORATION**

---

| | |
|:---|:---|
| By: | /s/ Masoud Toloue |
|  | Masoud Toloue, Ph.D. |
|  | President and Chief Executive Officer |

---

**SIGNATURES**

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 3 to the Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

---

| | | |
|:---|:---|:---|
| **Signature** | **Title** | **Date** |
| /s/ Masoud Toloue, Ph.D. | President, Chief Executive Officer and Director (principal executive officer) | July 11, 2025 |
| Masoud Toloue, Ph.D. |  |  |
| /s/ Vandana Sriram | Chief Financial Officer (principal financial officer and principal accounting officer) | July 11, 2025 |
| Vandana Sriram |  |  |
| \* | Director | July 11, 2025 |
| William Donnelly |  |  |
| \* | Director | July 11, 2025 |
| Jeffrey T. Elliot |  |  |
| \* | Director | July 11, 2025 |
| Karen A. Flynn |  |  |
| \* | Director | July 11, 2025 |
| Ivana Magovčević-Liebisch, Ph.D., J.D. |  |  |
| \* | Director | July 11, 2025 |
| Paul M. Meister |  |  |
| \* | Director | July 11, 2025 |
| David R. Walt, Ph.D. |  |  |
|  | Director | July 11, 2025 |
| Myla Lai-Goldman, M.D. |  |  |
|  | Director | July 11, 2025 |
| Scott Mendel |  |  |

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| | |
|:---|:---|
| \* | <u>By: /s/ Masoud Toloue, Ph.D.</u> |
|  | Masoud Toloue, Ph.D. |
|  | Attorney-in-Fact |

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## Exhibit 5.1

**Exhibit 5.1**

![](tm2520205d1_ex5-1img01.jpg)

July 11, 2025

Quanterix Corporation

900 Middlesex Turnpike

Billerica, MA 01821

Ladies and Gentlemen:

We have acted as counsel to Quanterix Corporation, a Delaware corporation (the "*Company*"), and are rendering this opinion in connection with the registration by the Company under the Securities Act of 1933 (the "*Securities Act*"), of the offer and sale of 253,181 shares of the Company's common stock, par value $0.001 per share (the "*Shares*"), issuable under the Akoya Biosciences, Inc. 2015 Equity Incentive Plan, as amended, and the Akoya Biosciences, Inc. 2021 Equity Incentive Plan (the "*Assumed Plans*"), which were assumed by the Company in connection with the consummation of the transactions contemplated by the Amended and Restated Agreement and Plan of Merger, dated as of April 28, 2025, by and among the Company, Wellfleet Merger Sub, Inc., and Akoya Biosciences, Inc. (the "*Merger Agreement*"), pursuant to the Post Effective Amendment No. 3 on Form S-8 to the Registration Statement on Form S-4 (File No. 333-284932) filed with the United States Securities and Exchange Commission (the "*Commission*") on the date hereof (as so amended, the "*Registration Statement*").

We have reviewed the Registration Statement, the Merger Agreement, the Assumed Plans, the Amended and Restated Certificate of Incorporation of the Company, and the Amended and Restated By-laws of the Company.

We have also reviewed such corporate records, certificates and other documents, and such questions of law, as we have deemed necessary or appropriate for the purposes of this opinion. We have assumed that all signatures are genuine, that all documents submitted to us as originals are authentic and that all copies of documents submitted to us conform to the originals.

We have relied as to certain matters on information obtained from public officials, officers of the Company and other sources believed by us to be responsible.

Based upon the foregoing, we are of the opinion that the Shares have been duly authorized and, when duly issued and sold as contemplated in the Registration Statement and in accordance with the terms of the Assumed Plans, will be validly issued, fully paid and non-assessable.

We are members of the bar of the District of Columbia. We do not express any opinion herein on any laws other than the Delaware General Corporation Law and reported judicial decisions interpreting such law.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement. We also hereby consent to the reference to our firm under the heading "Interests of Named Experts and Counsel" in the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act.

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| |
|:---|
| Very truly yours, |
| /s/ Covington & Burling LLP |

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## Exhibit 23.2

**Exhibit 23.2**

**Consent of Independent Registered Public Accounting Firm**

We consent to the reference to our firm under the caption "Experts" in the Post-Effective Amendment No. 3 on Form S-8 to the Registration Statement (Form S-4 No. 333-284932) and the related Proxy Statement/Prospectus pertaining to the Akoya Biosciences, Inc. 2021 Equity Incentive Plan and the Akoya Biosciences, Inc. 2015 Equity Incentive Plan and to the incorporation by reference of our reports dated March 17, 2025, with respect to the consolidated financial statements of Quanterix Corporation and the effectiveness of internal control over financial reporting of Quanterix Corporation included in its Annual Report (Form 10-K) for the year ended December 31, 2024, filed with the Securities and Exchange Commission.

/s/ Ernst & Young LLP

Boston, Massachusetts

July 11, 2025

## Exhibit 23.3

**Exhibit 23.3**

**Consent of Independent Registered Public Accounting Firm**

We consent to the incorporation by reference in this Post-Effective Amendment No. 3 on Form S-8 to the Registration Statement (No. 333-284932) on Form S-4 of Quanterix Corporation of our report dated March 17, 2025, relating to the consolidated financial statements of Akoya Biosciences, Inc. and its subsidiary, appearing in the Annual Report on Form 10-K of Akoya Biosciences, Inc. for the year ended December 31, 2024.

/s/ RSM US LLP

Boston, Massachusetts

July 11, 2025