First Eagle reports 5.8% stake in Quanterix Corp

First Eagle Investment Management, LLC reported beneficial ownership of 2,753,165 shares of Quanterix Corp common stock, representing 5.8% of the class as of June 30, 2026.

Rhea-AI Filing Summary

First Eagle Investment Management, LLC reported beneficial ownership of 2,753,165 shares of Quanterix Corp common stock, representing 5.8% of the class as of June 30, 2026. These shares are held with sole voting and sole dispositive power, with no shared voting or dispositive authority.

The First Eagle Small Cap Opportunity Fund, a registered investment company advised by First Eagle Investment Management, may be deemed to beneficially own 2,421,533 of these shares, representing 5.1% of Quanterix’s common stock. Clients of First Eagle Investment Management have the right to receive and direct the receipt of dividends and sale proceeds for these securities.

Key Figures

Beneficial ownership shares: 2,753,165 shares Ownership percentage: 5.8% Fund-level shares: 2,421,533 shares +4 more

7 metrics

Beneficial ownership shares 2,753,165 shares Shares of Quanterix Corp common stock deemed beneficially owned by First Eagle Investment Management

Ownership percentage 5.8% Percent of Quanterix Corp common stock class beneficially owned by First Eagle Investment Management

Fund-level shares 2,421,533 shares Quanterix shares beneficially owned by First Eagle Small Cap Opportunity Fund within the total reported holdings

Fund ownership percentage 5.1% Percent of Quanterix common stock beneficially owned by First Eagle Small Cap Opportunity Fund

Sole voting power 2,753,165 shares Shares over which First Eagle Investment Management has sole power to vote or direct the vote

Sole dispositive power 2,753,165 shares Shares over which First Eagle Investment Management has sole power to dispose or direct disposition

Ownership date reference 06/30/2026 Date referenced in the ownership header for the reported Quanterix stake

Key Terms

beneficial owner, sole voting power, sole dispositive power, Investment Advisers Act of 1940, +1 more

5 terms

beneficial owner regulatory

"is deemed to be the beneficial owner of 2,753,165 shares, or 5.84%"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

sole voting power regulatory

"Sole Voting Power 2,753,165.00 6 | Shared Voting Power 0.00"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

sole dispositive power regulatory

"Sole Dispositive Power 2,753,165.00 8 | Shared Dispositive Power 0.00"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Investment Advisers Act of 1940 regulatory

"an investment adviser registered under Section 203 of the Investment Advisers Act of 1940"

A U.S. federal law that sets rules for people and firms who give investment advice, requiring them to register with regulators, be honest about conflicts, keep records, and follow basic standards of care. It matters to investors because those rules act like licensing and consumer protections — similar to having safety standards for a mechanic — helping ensure advisers act in clients’ financial interests and reducing the risk of fraud or misuse of funds.

registered investment company regulatory

"The First Eagle Small Cap Opportunity Fund, a registered investment company for which FEIM acts"

A registered investment company is a pooled investment vehicle—such as a mutual fund or closed-end fund—that is officially registered with financial regulators and required to follow rules about disclosure, how it invests, and what fees it charges. Think of it as a shared basket of stocks or bonds managed for many investors; registration means regular reporting and oversight that help investors compare costs, understand risks, and know how easy it is to buy or sell their shares.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many Quanterix Corp (QTRX) shares does First Eagle Investment Management beneficially own?

First Eagle Investment Management is deemed the beneficial owner of 2,753,165 Quanterix Corp common shares, representing 5.8% of the class. It holds sole voting and sole dispositive power over these shares, with no shared voting or dispositive authority reported.

What percentage of Quanterix Corp (QTRX) does First Eagle Small Cap Opportunity Fund own?

The First Eagle Small Cap Opportunity Fund may be deemed to beneficially own 2,421,533 Quanterix shares, or 5.1% of the company’s common stock. This fund is a registered investment company for which First Eagle Investment Management acts as investment adviser.

Who has voting and dispositive power over Quanterix Corp (QTRX) shares held by First Eagle?

First Eagle Investment Management reports sole voting power and sole dispositive power over 2,753,165 Quanterix shares. It reports 0 shared voting power and 0 shared dispositive power, meaning no other party shares these powers on the reported holdings.

Do clients of First Eagle Investment Management benefit from the Quanterix Corp (QTRX) shares?

Clients of First Eagle Investment Management have the right to receive, and direct the receipt of, dividends and sale proceeds from the 2,753,165 Quanterix shares. First Eagle is deemed the beneficial owner because it acts as investment adviser to various clients holding these securities.

Why is First Eagle Investment Management filing a Schedule 13G for Quanterix Corp (QTRX)?

First Eagle Investment Management filed because it is deemed to beneficially own more than 5% of Quanterix’s common stock, specifically 5.8%. Crossing this ownership threshold for an equity security typically requires a beneficial ownership report such as a Schedule 13G.

What is the relationship between First Eagle Investment Management and First Eagle Small Cap Opportunity Fund regarding Quanterix Corp (QTRX)?

First Eagle Investment Management acts as investment adviser to the First Eagle Small Cap Opportunity Fund. The fund may be deemed to beneficially own 2,421,533 Quanterix shares within the 2,753,165 shares over which First Eagle Investment Management is deemed to have beneficial ownership.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/06/2026 - 10:40 AM Accepted by SEC EDGAR 08/06/2026 - 10:38 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Quanterix Corp

(Name of Issuer)

Common

(Title of Class of Securities)

74766Q101

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 74766Q101

1

Names of Reporting Persons

First Eagle Investment Management, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 2,753,165.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 2,753,165.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,753,165.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.8 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 74766Q101

1

Names of Reporting Persons

FIRST EAGLE SMALL CAP OPPORTUNITY FUND

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 2,421,533.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 2,421,533.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,421,533.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.1 %

12

Type of Reporting Person (See Instructions)

IC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Quanterix Corp
(b)	Address of issuer's principal executive offices: 900 MIDDLESEX TURNPIKE, BILLERICA, MA, 01821
Item 2.
(a)	Name of person filing: First Eagle Investment Management, LLC, FIRST EAGLE SMALL CAP OPPORTUNITY FUND
(b)	Address or principal business office or, if none, residence: 1345 Avenue of the Americas, New York, NY 10105, United States
(c)	Citizenship: DELAWARE
(d)	Title of class of securities: Common
(e)	CUSIP Number(s): 74766Q101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 2,753,165
(b)	Percent of class: 5.8 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 2,753,165
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 2,753,165
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. First Eagle Investment Management, LLC (FEIM), an investment adviser registered under Section 203 of the Investment Advisers Act of 1940, is deemed to be the beneficial owner of 2,753,165 shares, or 5.84% of the common stock believed to be outstanding as a result of acting as investment adviser to various clients. Clients of FEIM have the right to receive and the ultimate power to direct the receipt of dividends from, or the proceeds of the sale of, such securities. The First Eagle Small Cap Opportunity Fund, a registered investment company for which FEIM acts as investment adviser, may be deemed to beneficially own 2,421,533 of these 2,753,165 shares, or 5.14% of the Company's Common Stock.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

First Eagle Investment Management, LLC

Signature:	David O'Connor
Name/Title:	General Counsel
Date:	08/06/2026

FIRST EAGLE SMALL CAP OPPORTUNITY FUND

Signature:	David O'Connor
Name/Title:	General Counsel
Date:	08/06/2026