Quanterix Corp has 12 Schedule 13D or 13G filings on record since 2025-07-15. 4 holders' latest filing reports 5% or more of common stock, $0.001 par value per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Ameriprise Financial, Inc. | 7.5% | 3,542,374 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| BlackRock, Inc. | 7.3% | 2,843,760 | SCHEDULE 13G/A, 2025-07-17 | 2025-06-30 |
| First Eagle Investment Management, LLC | 5.8% | 2,753,165 | SCHEDULE 13G, 2026-08-06 | 2026-06-30 |
| Telegraph Hill Partners III, L.P. | 5.4% | 2,504,648 | SCHEDULE 13G, 2025-11-19 | 2025-09-30 |
| Kent Lake PR LLC | 4.5% | 2,089,500 | SCHEDULE 13D/A, 2025-07-15 | 2025-07-11 |
| Portolan Capital Management, LLC | 4.02% | 1,899,308 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
| The Vanguard Group | 0% | 0 | SCHEDULE 13G/A, 2026-03-27 | 2026-03-13 |
Purpose of Transaction (Item 4)
Kent Lake PR LLC
Item 4 is hereby amended to add the following: As previously disclosed in Amendment No. 1 to the Schedule 13D, on February 28, 2025, Kent Lake delivered a letter to the Issuer nominating Alexander G. Dickinson, Bruce Felt and Hakan Sakul (the "Nominees") for election to the Board of Directors of the Issuer (the "Board") at the 2025 annual meeting of stockholders (the "Annual Meeting"). On July 11, 2025, Kent Lake resubmitted its nomination of the Nominees for election to the Board at the Annual Meeting following the Issuer's disclosure that the Annual Meeting will now be held on September 23, 2025.Item 4 of the SCHEDULE 13D/A filed 2025-07-15
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-07-15 | Kent Lake PR LLC | 4.5% | SCHEDULE 13D/A |
| 2025-07-17 | BlackRock, Inc. | 7.3% | SCHEDULE 13G/A |
| 2025-08-13 | Portolan Capital Management, LLC | 9.36% | SCHEDULE 13G/A |
| 2025-11-14 | Ameriprise Financial, Inc. | 9.1% | SCHEDULE 13G/A |
| 2025-11-19 | Telegraph Hill Partners III, L.P. | 5.4% | SCHEDULE 13G |
| 2026-02-17 | Ameriprise Financial, Inc. | 10.7% | SCHEDULE 13G/A |
| 2026-03-27 | The Vanguard Group | 0% | SCHEDULE 13G/A |
| 2026-05-07 | Ameriprise Financial, Inc. | 2.1% | SCHEDULE 13G/A |
| 2026-05-15 | Portolan Capital Management, LLC | 6.25% | SCHEDULE 13G/A |
| 2026-05-15 | Ameriprise Financial, Inc. | 7.5% | SCHEDULE 13G/A |
| 2026-08-06 | First Eagle Investment Management, LLC | 5.8% | SCHEDULE 13G |
| 2026-08-14 | Portolan Capital Management, LLC | 4.02% | SCHEDULE 13G/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.