Quanterix QTRX Insider Ownership

NASDAQ QTRX

$2.87 +0.08 (+2.69%)

As of: Oct 22, 2026 · 11:53 AM EDT

Insider Holdings by Owner

4.62Mn Shares

Insider Ownership Statistics

as of 30 Sep, 2026

Insider Ownership

7.79%

▲+0.118% pp QoQ

Shares Held by Insiders

3.68Mn

filed for Sep 2026

▲+1.53% QoQ

Shares Outstanding

47.17Mn

47,167,000 shares

Direct Holdings

3.32Mn

Indirect: 354.03K

Net Shares Traded (QoQ)

+55.47K

net buying in Sep 2026

Insiders Holding Shares

with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Insiders

Bought Sold

Latest quarter —

Net over range —

Buying quarters —

Insider Ownership Summary

Updated Oct 16, 2026

In the last 12 months, insiders at Quanterix made open-market purchases of $296,049 (102.9K shares) and sold no shares on the open market.

A count shows 2 insiders buying QTRX stock on the open market over the past 12 months and none selling.
Among QTRX's insiders, William P. Donnelly (Director) was the top open-market buyer in the past 12 months, with $286,354 of stock purchased (99.4K shares) and the latest purchase on August 13, 2026.
In transactions other than open-market trades, Quanterix insiders received 110.39K shares in stock awards, acquired 38.98K shares through option exercises and conversions and gave up 16.38K shares to cover taxes or exercise prices over the past 12 months.
Per Business Quant data, Quanterix insiders hold 3.66Mn shares in total based on their latest Form 4 filings, up 1.08% from 3.62Mn shares at the end of Q2 2026 and up 3.84% from 3.52Mn shares at the end of Q3 2025.
Of the 3.66Mn shares held by Quanterix insiders, 3.31Mn shares (90.32%) are held directly and 354.03K shares (9.68%) indirectly, through trusts, partnerships, family members and other entities.
QTRX's insider total is spread across 16 insiders who have filed a Form 4 in the past two years.
QTRX's three largest insider shareholders, per their latest Form 4 filings, are David R. Walt (Director, 1.87Mn shares), Masoud Toloue (President & CEO, 507.31K shares) and Paul M. Meister (Director, 313.25K shares).
Of the shares held by QTRX insiders, 51.18% belong to David R. Walt.
Institutional holders reported 62.39% of Quanterix's outstanding shares for Q2 2026; insiders' latest Form 4 filings put their stake at about 7.76%, and other investors, including the public, hold the remaining 29.85%.
Over the past 12 months, 17 insiders reported transactions in Quanterix stock in 59 Form 4 filings.
Insider figures for QTRX include Form 4 filings through October 2, 2026.

Form 4 Holdings

Insiders Holding QTRX

Insiders 25

Shares held 4.62Mn

Of outstanding 9.80%

#	Insider	Position	Direct	Total	Share of Insiders	Last Filed
1	David R Walt	Director	1,872,890	1,872,890	40.5%	06 Jan, 2026
2	E Kevin Hrusovsky	Executive Chairman	910,249	910,249	19.7%	06 Jul, 2022
3	Masoud Toloue	President Ceo	507,310	507,310	11.0%	20 Jan, 2026
4	Paul M Meister	Director	313,253	313,253	6.8%	07 Jan, 2026
5	William P Donnelly	Executive Chair	169,365	169,365	3.7%	02 Oct, 2026
6	Keith Crandell	Director	131,236	131,236	2.8%	04 Apr, 2023
7	Michael A Doyle	Cfo And Treasurer	88,332	88,332	1.9%	02 Oct, 2023
8	Alan Bruce Sachs	Director	70,099	70,099	1.5%	06 Jan, 2026
9	Malcolm Garret Hampton	Director	70,099	70,099	1.5%	06 Jan, 2026
10	Sarah E. Hlavinka	Director	60,070	60,070	1.3%	03 Jul, 2025
11	Karen Flynn	Director	57,212	57,212	1.2%	06 Jan, 2026
12	David C. Duffy	Svp Rd And Cto	54,730	54,730	1.2%	28 Mar, 2022
13	Michael Francis Miller	Chief Technology Officer	39,543	39,543	0.9%	16 Oct, 2026
14	John J Fry	General Counsel Secretary	37,671	37,671	0.8%	03 Aug, 2022
15	Martin D Madaus	Director	36,908	36,908	0.8%	06 Jan, 2025
16	Dawn Mattoon	Sr. Vp, Diagnostics	36,876	36,876	0.8%	05 Apr, 2022
17	Vandana Sriram	Chief Financial Officer	31,283	31,283	0.7%	23 Jun, 2026
18	Scott Mendel	Director	28,454	28,454	0.6%	02 Oct, 2026
19	Mark T. Roskey	Svp, Strategic Partnerships	22,325	22,325	0.5%	05 Apr, 2022
20	Brian J Blaser	Director	19,049	19,049	0.4%	04 Jan, 2024
21	Ivana Magovcevic-Liebisch	Director	15,883	15,883	0.3%	02 Oct, 2026
22	Jeffrey Thomas Elliott	Director	15,345	15,345	0.3%	20 Aug, 2026
23	Goldman Myla Lai	Director	15,041	15,041	0.3%	09 Jul, 2026
24	Laurie J Olson	Director	13,738	13,738	0.3%	14 May, 2024
25	Benjamin Meadows	Chief Commercial Officer	3,500	3,500	0.1%	12 Jun, 2026

Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.

Form 4 Filings

1,518 Insider Transactions

Source SEC Form 4

Latest quarter Sep 2026

Date	Insider	Position	Transaction	Shares	Price	Value	Shares Held After	Ownership
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Acquired M	81	—	—	38,533	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed F	25	$3.07	$77	38,508	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Acquired M	136	—	—	38,644	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed F	41	$3.07	$126	38,603	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Acquired M	135	—	—	38,738	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed F	41	$3.07	$126	38,697	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Acquired M	372	—	—	39,069	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed F	111	$3.07	$341	38,958	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Acquired M	834	—	—	39,792	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed F	249	$3.07	$764	39,543	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed M	81	$0.00	$0	355	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed M	136	$0.00	$0	709	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed M	135	$0.00	$0	2,171	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed M	372	$0.00	$0	7,085	Direct
15 Oct, 2026	Michael Francis Miller	Chief Technology Officer	Disposed M	834	$0.00	$0	23,355	Direct
02 Oct, 2026	Ivana Magovcevic-Liebisch	Director	Acquired M	4,224	—	—	15,883	Direct
01 Oct, 2026	William P Donnelly	Director	Acquired A	6,964	$3.41	$23.75K	169,365	Direct
01 Oct, 2026	Scott Mendel	Director	Acquired A	4,398	$3.41	$15.00K	28,454	Direct
02 Oct, 2026	Ivana Magovcevic-Liebisch	Director	Disposed M	4,224	$0.00	$0	4,352	Direct
15 Sep, 2026	James Edward Jr. Gute	Chief Commercial Officer	Acquired A	260,315	$0.00	$0	260,315	Direct

Showing 1 to 20 of 1,518 transactions