Prothena Corporation plc
Ownership
Ownership Structure
Who owns Prothena Corporation plc (PRTA)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 68.0% of the shares are freely tradable; institutional investors hold 90.7%.
Largest Shareholders
Institutions
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| FMR Inc | 14.71 | 7,551,218 | +0.0 | 03/31/2026 |
| Rubric Capital Management LP | 9.74 | 5,000,000 | +36.0 | 03/31/2026 |
| BlackRock Inc | 9.05 | 4,644,160 | +13.1 | 03/31/2026 |
| State Street Corp | 3.78 | 1,938,498 | -14.5 | 03/31/2026 |
| D. E. Shaw & Co LP | 3.14 | 1,611,457 | -8.6 | 06/30/2026 |
| ADAR1 Capital Management LLC | 3.08 | 1,581,443 | +8.5 | 03/31/2026 |
| Acadian Asset Management LLC | 3.01 | 1,547,593 | +1,457.7 | 03/31/2026 |
Funds
| Name | Stake (%) | Shares | Change (%) | Date |
|---|---|---|---|---|
| Fidelity Growth Compy Commingled Pl S | 6.50 | 3,335,877 | +0.0 | 07/31/2026 |
| Fidelity Growth Company Fund | 4.34 | 2,228,375 | +0.0 | 07/31/2026 |
| State Street® SPDR® S&P® Biotech ETF | 2.99 | 1,533,704 | -1.1 | 08/31/2026 |
Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.
Insider holdings
| Person | Role | Shares | Value | As of | Type |
|---|---|---|---|---|---|
| Scully William P | 10% Owner | 910,500 | 7,739,250 $ | Aug 7, 2026 | both |
| Kinney Gene G. | President and CEO | 68,793 | 584,741 $ | Jul 28, 2026 | direct |
| Kingston Anne Evans | Chief Strategy Officer | 55,782 | 474,147 $ | Jul 29, 2026 | direct |
| Smith Brandon S. | Chief Operating Officer | 52,000 | 442,000 $ | Jul 28, 2026 | direct |
| Swanson Chad J. | Chief Development Officer | 40,733 | 346,231 $ | Jul 28, 2026 | direct |
| Nguyen Tran | Chief Strategy Officer and CFO | 40,205 | 341,743 $ | Jul 28, 2026 | direct |
| Isaacs Michael John | General Counsel & Company Sec. | 35,745 | 303,833 $ | Jul 29, 2026 | direct |
| Zago Wagner M. | Chief Scientific Officer | 34,000 | 289,000 $ | Jul 28, 2026 | direct |
| Walker Karin L | Chief Accounting Officer | 10,000 | 85,000 $ | Jul 28, 2026 | direct |
Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.
Insiders
Insider Transactions
| Date | Person | Role | Type | Shares | Price | Value |
|---|---|---|---|---|---|---|
| Sep 2, 2026 | Scully William P | 10% Owner | Buy | 27,000 | 9.47 | 255,739 |
| Aug 20, 2026 | Scully William P | 10% Owner | Buy | 50,000 | 8.79 | 439,430 |
| Aug 18, 2026 | Scully William P | 10% Owner | Other | 627,553 | 0.00 | – |
| Aug 17, 2026 | Scully William P | 10% Owner | Other | 336,000 | 0.00 | – |
| Aug 10, 2026 | Scully William P | 10% Owner | Other | 251,553 | 0.00 | – |
| Aug 7, 2026 | Scully William P | 10% Owner | Buy | 3,500 | 8.62 | 30,167 |
| Aug 7, 2026 | Scully William P | 10% Owner | Buy | 34,000 | 8.62 | 293,053 |
| Jul 29, 2026 | Kingston Anne Evans | Chief Strategy Officer | Sell | 7,662 | 8.47 | 64,919 |
| Jul 29, 2026 | Isaacs Michael John | General Counsel & Company Sec. | Sell | 8,386 | 8.47 | 71,055 |
| Jul 28, 2026 | Zago Wagner M. | Chief Scientific Officer | Other | 51,000 | 8.56 | 436,560 |
| Jul 28, 2026 | Zago Wagner M. | Chief Scientific Officer | Other | 51,000 | – | – |
| Jul 28, 2026 | Walker Karin L | Chief Accounting Officer | Other | 15,000 | 8.56 | 128,400 |
| Jul 28, 2026 | Walker Karin L | Chief Accounting Officer | Other | 15,000 | – | – |
| Jul 28, 2026 | Swanson Chad J. | Chief Development Officer | Other | 3,467 | 8.56 | 29,678 |
| Jul 28, 2026 | Swanson Chad J. | Chief Development Officer | Other | 40,800 | 8.56 | 349,248 |
| Jul 28, 2026 | Swanson Chad J. | Chief Development Officer | Other | 51,000 | – | – |
| Jul 28, 2026 | Smith Brandon S. | Chief Operating Officer | Other | 78,000 | 8.56 | 667,680 |
| Jul 28, 2026 | Smith Brandon S. | Chief Operating Officer | Other | 78,000 | – | – |
| Jul 28, 2026 | Nguyen Tran | Chief Strategy Officer and CFO | Other | 57,000 | 8.56 | 487,920 |
| Jul 28, 2026 | Nguyen Tran | Chief Strategy Officer and CFO | Other | 57,000 | – | – |
| Jul 28, 2026 | Kinney Gene G. | President and CEO | Other | 84,000 | 8.56 | 719,040 |
| Jul 28, 2026 | Kinney Gene G. | President and CEO | Other | 84,000 | – | – |
| Jul 28, 2026 | Kingston Anne Evans | Chief Strategy Officer | Other | 3,498 | 8.56 | 29,943 |
| Jul 28, 2026 | Isaacs Michael John | General Counsel & Company Sec. | Other | 4,694 | 8.56 | 40,181 |
Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →
Data as of: September 17, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)
Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.