Ameriprise reports 990,224 shares (2.1%) in Quanterix

Ameriprise Financial, Inc. filed an Amendment No. 6 to a Schedule 13G/A reporting shared voting and dispositive power over 990,224 shares of Quanterix Corp common stock, representing 2.1% of the class.

Rhea-AI Filing Summary

Ameriprise Financial, Inc. filed an Amendment No. 6 to a Schedule 13G/A reporting shared voting and dispositive power over 990,224 shares of Quanterix Corp common stock, representing 2.1% of the class. The filing lists Quanterix's principal executive office at 900 Middlesex Turnpike, Billerica, MA and states that AFI disclaims beneficial ownership of the reported shares.

Insights

Institutional Ownership Analyst

Minor passive holder update: Ameriprise reports 2.1% shared holdings in QTRX.

Ameriprise amended its Schedule 13G/A to show shared voting and dispositive power over 990,224 shares of Quanterix common stock. The filing characterizes this as passive ownership and includes a disclaimer that AFI disclaims beneficial ownership.

Because the stake is below typical activist thresholds, the holding is not likely to change governance; subsequent filings would show material shifts.

Key Figures

Shares with shared power: 990,224 shares Percent of class: 2.1% CUSIP: 74766Q101 +1 more

4 metrics

Shares with shared power 990,224 shares shared voting and dispositive power reported on Amendment No. 6

Percent of class 2.1% percent of Quanterix common stock reported on Schedule 13G/A

CUSIP 74766Q101 Quanterix Corp common stock CUSIP listed on the filing

Filing type Schedule 13G/A (Amendment No. 6) ownership disclosure by Ameriprise Financial, Inc.

Key Terms

Schedule 13G/A, beneficial ownership, shared dispositive power

3 terms

Schedule 13G/A regulatory

"Amendment No. 6 to a Schedule 13G/A reporting ownership"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficial ownership regulatory

"AFI disclaims beneficial ownership of any shares reported on this Schedule"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared dispositive power financial

"Shared Dispositive Power 990,224.00"

FAQ

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

What does Ameriprise report owning in QTRX?

Ameriprise reports shared voting and dispositive power over 990,224 shares, equal to 2.1% of the class. These figures appear on Amendment No. 6 to a Schedule 13G/A and are presented as shared, not sole, powers.

Does Ameriprise claim beneficial ownership of Quanterix shares?

No. The filing states that Ameriprise Financial, Inc. "disclaims beneficial ownership" of the reported shares. The disclosure records voting/dispositive powers but denies direct beneficial ownership.

What class and CUSIP are covered in the filing?

The filing covers Quanterix Corp Common Stock with CUSIP 74766Q101. The issuer's principal address is listed as 900 Middlesex Turnpike, Billerica, MA in the filing.

What does "shared dispositive power" mean on a Schedule 13G/A?

Shared dispositive power means the reporting person shares the authority to direct how the securities are disposed. The Schedule 13G/A indicates Ameriprise shares that authority over the 990,224 shares disclosed.

Is the Ameriprise stake in QTRX considered activist or passive?

Passive. The Schedule 13G/A format and the filing language indicate a passive reporting position. The stake is reported at 2.1%, below common activist engagement thresholds.

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

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Accepted by SEC EDGAR 05/07/2026 - 10:19 AM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 6)

Quanterix Corp

(Name of Issuer)

Common Stock

(Title of Class of Securities)

74766Q101

(CUSIP Number)

04/30/2026

(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

Ameriprise Financial, Inc.

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 0.00
6	Shared Voting Power 990,224.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 990,224.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

990,224.00

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)

2.1 %

12

Type of Reporting Person (See Instructions)

HC

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: Ameriprise Financial, Inc. ("AFI")
(b)	Address or principal business office or, if none, residence: 145 Ameriprise Financial Center, Minneapolis, MN 55474
(c)	Citizenship: Delaware
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 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: Incorporated by reference to Items (5)-(9) and (11) of the cover page pertaining to the reporting person. AFI disclaims beneficial ownership of any shares reported on this Schedule.
(b)	Percent of class: The information required by Item 4(b) is set forth in Rows (5)-(9) and (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c) is set forth in Rows (5)-(9) and (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c) is set forth in Rows (5)-(9) and (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c) is set forth in Rows (5)-(9) and (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c) is set forth in Rows (5)-(9) and (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each Reporting Person.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
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.

Ameriprise Financial, Inc.

Signature:	/s/ Michael G. Clarke
Name/Title:	Michael G. Clarke, Senior Vice President, North America Head of Operations & Investor Services
Date:	05/07/2026

Comments accompanying signature: Contact Information Charles Chiesa VP Fund Treasurer Global Operations and Investor Services Telephone: 617-385-9593