Feeds › Ownership stakes (13D / 13G)
Ownership stakes (13D / 13G)
Investors who own more than 5% of a company, from activists (13D) to passive holders (13G).
About this data
- What it is
- An investor who owns more than 5% of a public company must say so. Investors who may try to influence the company, such as activists, file the longer Schedule 13D; passive holders file the shorter Schedule 13G.
- Who files it
- The investor, within days of crossing 5%, and again whenever the stake changes materially.
- How current
- We collect new filings throughout the day on SEC business days.
- Worth knowing
- 13G filings are far more common than 13D. A 13D usually means the investor intends to push for changes, so it tends to get more attention.
All of this comes from public filings.
Source and freshness · Information, not investment advice (disclaimer).
Filings per day, last 30 days
13D (activist) 13G (passive)
Latest ownership filings
Showing: ticker PRTA
| Filed | ScheduleBoth report a stake of more than 5%. A 13D is filed by investors who may try to influence the company, such as activists; a 13G by passive holders. | Company | Investor | Shares | % of shares | Filing |
|---|---|---|---|---|---|---|
| Nov 13, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 6.40M | 12.5% | SCHEDULE 13G/A ↗ |
| Aug 19, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 5.25M | 10.2% | SCHEDULE 13G/A ↗ |
| Aug 14, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 5.01M | 9.8% | SCHEDULE 13G/A ↗ |
| Aug 6, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Abigail P. Johnson | 7.20M | 13.8% | SCHEDULE 13G/A ↗ |
| Aug 6, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | FMR LLC | 7.20M | 13.8% | SCHEDULE 13G/A ↗ |
| Jul 29, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | BlackRock, Inc. | 3.59M | 6.9% | SCHEDULE 13G/A ↗ |
| May 15, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | David Rosen | 5.00M | 9.3% | SCHEDULE 13G/A ↗ |
| May 15, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Rubric Capital Management LP | 5.00M | 9.3% | SCHEDULE 13G/A ↗ |
| May 11, 2026 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 5.38M | 10.3% | SCHEDULE 13G/A ↗ |
| Feb 13, 2026 | SCHEDULE 13G | PRTA Prothena Corporation plc | David Rosen | 3.68M | 6.8% | SCHEDULE 13G ↗ |
| Feb 13, 2026 | SCHEDULE 13G | PRTA Prothena Corporation plc | Rubric Capital Management LP | 3.68M | 6.8% | SCHEDULE 13G ↗ |
| Nov 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Daniel Schneeberger | 1.47M | 2.7% | SCHEDULE 13G/A ↗ |
| Nov 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | ADAR1 Capital Management GP, LLC | 1.19M | 2.2% | SCHEDULE 13G/A ↗ |
| Nov 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | ADAR1 Capital Management, LLC | 1.47M | 2.7% | SCHEDULE 13G/A ↗ |
| Nov 12, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 4.50M | 8.4% | SCHEDULE 13G/A ↗ |
| Nov 12, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 5.28M | 9.8% | SCHEDULE 13G/A ↗ |
| Oct 17, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | BlackRock, Inc. | 3.09M | 5.7% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | Daniel Schneeberger | 2.89M | 5.4% | SCHEDULE 13G ↗ |
| Aug 14, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | ADAR1 Capital Management GP, LLC | 2.89M | 5.4% | SCHEDULE 13G ↗ |
| Aug 14, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | ADAR1 Capital Management, LLC | 3.38M | 6.3% | SCHEDULE 13G ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William Arsani | 0 | 0.0% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Logos GP LLC | 0 | 0.0% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Logos Global Master Fund LP | 0 | 0.0% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Logos Global Management GP LLC | 0 | 0.0% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Logos Global Management LP | 0 | 0.0% | SCHEDULE 13G/A ↗ |
| Aug 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | T. Rowe Price Associates, Inc. | 71,047 | 0.1% | SCHEDULE 13G/A ↗ |
| Aug 13, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 4.35M | 8.1% | SCHEDULE 13G/A ↗ |
| Aug 13, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 5.35M | 9.9% | SCHEDULE 13G/A ↗ |
| Jun 5, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Investment Advisors Holdings LLP | 108,208 | 0.2% | SCHEDULE 13G/A ↗ |
| Jun 5, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Group Holdings LLP | 108,208 | 0.2% | SCHEDULE 13G/A ↗ |
| Jun 5, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Management Group LLP | 108,208 | 0.2% | SCHEDULE 13G/A ↗ |
| Jun 4, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | William Arsani | 2.95M | 5.5% | SCHEDULE 13G ↗ |
| Jun 4, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | Logos GP LLC | 2.95M | 5.5% | SCHEDULE 13G ↗ |
| Jun 4, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | Logos Global Master Fund LP | 2.95M | 5.5% | SCHEDULE 13G ↗ |
| Jun 4, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | Logos Global Management GP LLC | 2.95M | 5.5% | SCHEDULE 13G ↗ |
| Jun 4, 2025 | SCHEDULE 13G | PRTA Prothena Corporation plc | Logos Global Management LP | 2.95M | 5.5% | SCHEDULE 13G ↗ |
| May 29, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | EcoR1 Capital Fund Qualified, L.P. | 0 | 0.0% | SCHEDULE 13D/A ↗ |
| May 29, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | Oleg Nodelman | 0 | 0.0% | SCHEDULE 13D/A ↗ |
| May 29, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | EcoR1 Capital, LLC | 0 | 0.0% | SCHEDULE 13D/A ↗ |
| May 15, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 4.59M | 8.5% | SCHEDULE 13G/A ↗ |
| May 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 5.61M | 10.4% | SCHEDULE 13G/A ↗ |
| May 6, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | EcoR1 Capital Fund Qualified, L.P. | 4.97M | 9.2% | SCHEDULE 13D/A ↗ |
| May 6, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | Oleg Nodelman | 5.30M | 9.9% | SCHEDULE 13D/A ↗ |
| May 6, 2025 | SCHEDULE 13D/A (amended) | PRTA Prothena Corporation plc | EcoR1 Capital, LLC | 5.30M | 9.9% | SCHEDULE 13D/A ↗ |
| Feb 21, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | William P. Scully | 5.56M | 10.3% | SCHEDULE 13G/A ↗ |
| Feb 14, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Todd W. Fennell | 4.65M | 8.6% | SCHEDULE 13G/A ↗ |
| Feb 10, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Management Company LLP | 5.13M | 9.5% | SCHEDULE 13G/A ↗ |
| Feb 10, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Investment Advisors Holdings LLP | 5.13M | 9.5% | SCHEDULE 13G/A ↗ |
| Feb 10, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Group Holdings LLP | 5.13M | 9.5% | SCHEDULE 13G/A ↗ |
| Feb 10, 2025 | SCHEDULE 13G/A (amended) | PRTA Prothena Corporation plc | Wellington Management Group LLP | 5.13M | 9.5% | SCHEDULE 13G/A ↗ |
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