Quanterix Corporation (QTRX) Ownership
QTRX ownership summary
as of October 18, 2026- Institutions
- 71.2% of shares outstanding
- Insiders
- 6.37% of shares outstanding
- Shares outstanding
- 47.3M
- Float
- 38.0M shares available to trade
- Short interest
- 12.01% 5.0M shares short
- Days to cover
- 5.60 short interest up 1.4% vs prior month
- Institutions 71.22%
- Insiders 6.37%
- Other investors 22.41%
QTRX top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Arnhold & S. Bleichroeder Advisers, LLC | 11.64% | 5.5M | $15.8M | +4.2M (+323.5%) | June 30, 2026 |
| 2 | BlackRock Inc | 7.69% | 3.6M | $10.4M | +357,816 (+10.9%) | June 30, 2026 |
| 3 | Blue Water Life Science Advisors, LLC | 7.35% | 3.5M | $10.0M | +1.3M (+62.2%) | June 30, 2026 |
| 4 | Portolan Capital Management, LLC | 4.02% | 1.9M | $5.5M | −1.0M (−35.5%) | June 30, 2026 |
| 5 | Vanguard Capital Management, LLC | 3.81% | 1.8M | $5.2M | +16,031 (+0.9%) | June 30, 2026 |
| 6 | Lionhunter Capital Management, LLC | 3.17% | 1.5M | $4.3M | +1.5M (0.0%) | June 30, 2026 |
| 7 | AQR Capital Management LLC | 2.84% | 1.3M | $3.9M | +1.3M (+1,496.3%) | June 30, 2026 |
| 8 | Geode Capital Management, LLC | 2.39% | 1.1M | $3.2M | +136,613 (+13.7%) | June 30, 2026 |
| 9 | Ameriprise Financial Inc | 2.09% | 987K | $2.8M | −2.6M (−72.1%) | June 30, 2026 |
| 10 | Marshall Wace Asset Management Ltd | 2.06% | 974K | $2.8M | +351,492 (+56.5%) | June 30, 2026 |
| 11 | State Street Corp | 1.97% | 932K | $2.7M | +34,030 (+3.8%) | June 30, 2026 |
| 12 | Tikvah Management LLC | 1.21% | 572K | $1.6M | −64 (−0.0%) | June 30, 2026 |
| 13 | Vanguard Portfolio Management, LLC | 1.04% | 490K | $1.4M | −87,034 (−15.1%) | June 30, 2026 |
| 14 | Jacobs Levy Equity Management, Inc. | 1.03% | 488K | $1.4M | +487,600 (0.0%) | June 30, 2026 |
| 15 | Morgan Stanley - Brokerage Accounts | 0.95% | 448K | $1.3M | −160,168 (−26.3%) | June 30, 2026 |
| 16 | Jane Street Group LLC | 0.89% | 419K | $1.2M | +263,395 (+169.2%) | June 30, 2026 |
| 17 | GSA Capital Partners LLP | 0.87% | 410K | $1.2M | +314,724 (+329.5%) | June 30, 2026 |
| 18 | Tudor Investment Corp Et AL | 0.85% | 400K | $1.1M | +84,401 (+26.7%) | June 30, 2026 |
| 19 | Dimensional Fund Advisors, Inc. | 0.84% | 398K | $1.1M | −45,285 (−10.2%) | June 30, 2026 |
| 20 | Northern Trust Corp | 0.71% | 337K | $967,841 | −12,431 (−3.6%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 13 holders added 10.3M shares and 7 cut 3.9M.
QTRX top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | First Eagle Small Cap Opportunity I | 4.05% | 1.9M | $5.5M | −216,735 (−10.2%) | September 30, 2026 |
| 2 | Strategic Advisers U.S. Total Stock | 3.05% | 1.4M | $4.1M | — | August 31, 2026 |
| 3 | Vanguard MStar Total Stk Mkt Idx Invest | 2.65% | 1.3M | $3.6M | — | August 31, 2026 |
| 4 | iShares Russell 2000 ETF | 2.39% | 1.1M | $3.2M | −12,992 (−1.1%) | September 30, 2026 |
| 5 | Columbia Small Cap Value Discv A | 1.47% | 694K | $2.0M | +4,400 (+0.6%) | August 31, 2026 |
| 6 | Fidelity Small Cap Index | 0.98% | 465K | $1.3M | +2,144 (+0.5%) | July 31, 2026 |
| 7 | iShares Russell 2000 Value ETF | 0.83% | 394K | $1.1M | +598 (+0.2%) | September 30, 2026 |
| 8 | iShares Biotechnology ETF | 0.65% | 310K | $888,948 | −2,344 (−0.8%) | September 30, 2026 |
| 9 | Vanguard Russell 2000 ETF | 0.52% | 247K | $707,498 | +1,460 (+0.6%) | September 30, 2026 |
| 10 | Fidelity Enhanced Small Cap Core ETF | 0.50% | 238K | $684,423 | +498 (+0.2%) | September 30, 2026 |
| 11 | Fidelity Extended Market Index | 0.44% | 210K | $603,911 | −31,092 (−12.9%) | August 31, 2026 |
| 12 | First Eagle US Small Cap Opp I-UC | 0.38% | 182K | $522,225 | −13,898 (−7.1%) | September 30, 2026 |
| 13 | DFA US Micro Cap I | 0.34% | 159K | $456,511 | — | August 31, 2026 |
| 14 | iShares Micro-Cap ETF | 0.29% | 137K | $392,610 | −943 (−0.7%) | September 30, 2026 |
| 15 | CREF Total Global Stock Account R3 | 0.28% | 131K | $376,352 | −18,747 (−12.5%) | August 31, 2026 |
| 16 | Columbia VP Small Cap Value Discovery 1 | 0.26% | 121K | $347,715 | −1,300 (−1.1%) | August 31, 2026 |
| 17 | Vanguard Health Care ETF | 0.25% | 120K | $343,843 | +926 (+0.8%) | September 30, 2026 |
| 18 | Schwab Small Cap Index | 0.22% | 104K | $299,668 | — | August 31, 2026 |
| 19 | Invesco RAFI US 1500 Small-Mid ETF | 0.20% | 96K | $274,656 | — | September 30, 2026 |
| 20 | Vanguard Strategic Small-Cap Equity Inv | 0.19% | 91K | $260,275 | — | June 30, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
QTRX insider transactions
latest 5| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2025-06-13 | David R Walt | Buy | $6.14 | 123,990 | $761,299 |
| 2025-06-12 | David R Walt | Buy | $6.23 | 36,010 | $224,342 |
| 2025-06-09 | David R Walt | Buy | $5.34 | 78,131 | $417,220 |
| 2025-06-06 | David R Walt | Buy | $5.43 | 131,869 | $716,049 |
| 2025-06-06 | William P Donnelly | Buy | $5.44 | 93,113 | $506,535 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
QTRX shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns QTRX
Institutional investors own 71.2% of Quanterix's shares and insiders 6.37%. The largest holder is Arnhold & S. Bleichroeder Advisers, LLC with 11.64% of the shares (5.5M), as of June 30, 2026. Among the top 20 institutions, 13 added shares and 7 reduced their stake in the latest filings. Short interest is 12.01% of the float, or 5.60 days of average trading volume. The share count rose 2,239.0% since 2015.
Related: QTRX analyst forecast, QTRX key metrics. See the QTRX stock overview for the latest quote and news.
QTRX ownership FAQ
Who owns the most Quanterix stock?
The largest shareholders of Quanterix are Arnhold & S. Bleichroeder Advisers, LLC (11.64%), BlackRock Inc (7.69%), Blue Water Life Science Advisors, LLC (7.35%), Portolan Capital Management, LLC (4.02%), Vanguard Capital Management, LLC (3.81%).
What percentage of Quanterix is owned by institutions?
Institutions hold 71.2% of Quanterix's shares outstanding; insiders hold 6.37%.
Which funds own Quanterix?
The largest fund holders of Quanterix are First Eagle Small Cap Opportunity I (4.05%), Strategic Advisers U.S. Total Stock (3.05%), Vanguard MStar Total Stk Mkt Idx Invest (2.65%), iShares Russell 2000 ETF (2.39%), Columbia Small Cap Value Discv A (1.47%).
What is Quanterix's short interest?
5.0M shares of Quanterix were sold short, 12.01% of the float; at the average daily volume it would take 5.60 days to cover.
Are insiders buying or selling Quanterix?
Of the latest 5 reported insider transactions in Quanterix (since June 6, 2025), 5 were purchases and 0 were sales.
How many shares of Quanterix are outstanding?
Quanterix has 47.3M shares outstanding, of which 38.0M are in the public float.