As of November 7, 2026, 5 holders' latest Schedule 13D or 13G filings report owning 5% or more of Prothena Corp Public Ltd Co. The largest reported stake is Fmr LLC's, at 13.8%. 16 filings are on record since August 13, 2025 (Schedule 13G/A, August 6, 2026).
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Key facts
- · Reporting person: Fennell Todd W. · Sole voting: 0 · Shared voting: 5,248,846 · Sole dispositive: 0 · Shared dispositive: 5,248,846 · SCHEDULE 13G/A, 2026-08-19
- · Holder: Fennell Todd W. · Percent: 9.8% · SCHEDULE 13G/A
- · Reporting person: Fmr LLC · Sole voting: 7,199,218 · Shared voting: 0 · Sole dispositive: 7,199,218 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-08-06
- · Reporting person: BlackRock, Inc. · Sole voting: 3,533,090 · Shared voting: 0 · Sole dispositive: 3,587,480 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-07-29
- · Holder: Rubric Capital Management LP · Percent: 9.29% · SCHEDULE 13G/A
Prothena Corp Public Ltd Co has 16 Schedule 13D or 13G filings on record since 2025-08-13. 5 holders' latest filing reports 5% or more of ordinary shares, $0.01 par value. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Fmr LLC | 13.8% | 7,199,218 | SCHEDULE 13G/A, 2026-08-06 | 2026-06-30 |
| 10.3% | 5,378,846 | SCHEDULE 13G/A, 2026-05-11 | 2026-05-07 | |
| 10.2% | 5,248,846 | SCHEDULE 13G/A, 2026-08-19 | 2026-08-18 | |
| Rubric Capital Management LP | 9.29% | 5,000,000 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
| BlackRock, Inc. | 6.9% | 3,587,480 | SCHEDULE 13G/A, 2026-07-29 | 2026-06-30 |
| ADAR1 Capital Management, LLC | 2.7% | 1,469,098 | SCHEDULE 13G/A, 2025-11-14 | 2025-09-30 |
| T. Rowe Price Associates, Inc. | 0.1% | 71,047 | SCHEDULE 13G/A, 2025-08-14 | 2025-06-30 |
| Logos Global Management LP | 0% | 0 | SCHEDULE 13G/A, 2025-08-14 | 2025-06-30 |
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More on Prothena Corp Public Ltd Co and the records around it.
Prothena Corp Public Ltd Co elsewhere on the record
Companies that share a holder
- Logos Global Management LP also filed stake reports on 14 other companies: Longeveron Inc. (Sep 2026), ACHIEVE LIFE SCIENCES, INC. (Aug 2026), Yarrow Bioscience, Inc. (Aug 2026)
- ADAR1 Capital Management, LLC also filed stake reports on 29 other companies: InMed Pharmaceuticals, Inc. (Oct 2026), Tenax Therapeutics, Inc. (Sep 2026), Adagio Medical Holdings, Inc. (Aug 2026)
- Rubric Capital Management LP also filed stake reports on 32 other companies: ARDELYX, INC. (Aug 2026), Enovis Corporation (Aug 2026), MeiraGTx Holdings plc (Aug 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Fmr LLC | 7,199,218 | 0 | 7,199,218 | 0 | SCHEDULE 13G/A, 2026-08-06 |
| Abigail P. Johnson | 0 | 0 | 7,199,218 | 0 | SCHEDULE 13G/A, 2026-08-06 |
| Fennell Todd W. | 0 | 5,248,846 | 0 | 5,248,846 | SCHEDULE 13G/A, 2026-08-19 |
| BlackRock, Inc. | 3,533,090 | 0 | 3,587,480 | 0 | SCHEDULE 13G/A, 2026-07-29 |
The latest filing identifies Prothena Corp Public Ltd Co by CUSIP G72800108 and gives its principal executive office as 77 SIR JOHN ROGERSON'S QUAY, BLOCK C, GRAND CANAL DOCKLANDS, DUBLIN 2 (SCHEDULE 13G/A, 2026-08-19).
What the percentages are based on
According to the Issuers most recent Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, the number of shares outstanding as of July 30, 2026 was 51,336,974. The Ordinary Shares which the Reporting Person may be deemed to beneficially own constitute approximately 10.22% of such total number of shares.Fennell Todd W., SCHEDULE 13G/A, 2026-08-19
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-13 | Scully William P | 9.9% | SCHEDULE 13G/A |
| 2025-08-13 | Fennell Todd W. | 8.1% | SCHEDULE 13G/A |
| 2025-08-14 | T. Rowe Price Associates, Inc. | 0.1% | SCHEDULE 13G/A |
| 2025-08-14 | Logos Global Management LP | 0% | SCHEDULE 13G/A |
| 2025-08-14 | ADAR1 Capital Management, LLC | 6.3% | SCHEDULE 13G |
| 2025-10-17 | BlackRock, Inc. | 5.7% | SCHEDULE 13G/A |
| 2025-11-12 | Scully William P | 9.8% | SCHEDULE 13G/A |
| 2025-11-12 | Fennell Todd W. | 8.4% | SCHEDULE 13G/A |
| 2025-11-14 | ADAR1 Capital Management, LLC | 2.7% | SCHEDULE 13G/A |
| 2026-02-13 | Rubric Capital Management LP | 6.83% | SCHEDULE 13G |
| 2026-05-11 | Scully William P | 10.3% | SCHEDULE 13G/A |
| 2026-05-15 | Rubric Capital Management LP | 9.29% | SCHEDULE 13G/A |
| 2026-07-29 | BlackRock, Inc. | 6.9% | SCHEDULE 13G/A |
| 2026-08-06 | Fmr LLC | 13.8% | SCHEDULE 13G/A |
| 2026-08-14 | Fennell Todd W. | 9.8% | SCHEDULE 13G/A |
| 2026-08-19 | Fennell Todd W. | 10.2% | SCHEDULE 13G/A |
Questions about who owns Prothena Corp Public Ltd Co
Who owns Prothena Corp Public Ltd Co?
On this page, 5 holders' latest ownership filings report 5% or more of Prothena Corp Public Ltd Co: Fmr LLC (13.8%, Schedule 13G/A, filed 2026-08-06), Scully William P (10.3%, Schedule 13G/A, filed 2026-05-11), Fennell Todd W. (10.2%, Schedule 13G/A, filed 2026-08-19), Rubric Capital Management LP (9.29%, Schedule 13G/A, filed 2026-05-15) and BlackRock, Inc. (6.9%, Schedule 13G/A, filed 2026-07-29).
Who are the largest shareholders of Prothena Corp Public Ltd Co?
By the share each holder's latest filing reports, the largest holders of Prothena Corp Public Ltd Co on this page are Fmr LLC (13.8%), Scully William P (10.3%) and Fennell Todd W. (10.2%).
When did Fmr LLC buy into Prothena Corp Public Ltd Co?
The filings give report dates, not purchase dates. The earliest filing from Fmr LLC on this page is the Schedule 13G/A, filed 2026-08-06, reporting 13.8%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 16 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Prothena Corp Public Ltd Co
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| October 2, 2026 | Leadership change: Chad J. Swanson departs | — | Leadership changes | Source |
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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.