Prothena Corporation plc (PRTA) Insider Trading
Over the last 3 months, PRTA insiders made 6 open-market buys and 2 sales, a net purchase of $2.3M (SEC Form 4). Over the last 6 months, 125 institutions increased and 113 reduced their position (13F).
Insider Activity
Sentiment
94/100
Buys (3m)
6
Sells (3m)
2
Net (3m)
$2.3M
Insiders buying
Insider trades by month Buys Sells
Jan
May
May
Jun
Jul
Aug
Context3-month price -4%Institutions accumulating (13F)
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| Aug 21, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 50,000 | $8.79 |
| Aug 10, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 3,500 | $8.62 |
| Aug 10, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 34,000 | $8.62 |
| Jul 30, 2026 | Isaacs Michael Johnofficer: General Counsel & Company Sec. | Sell | 8,386 | $8.47 |
| Jul 30, 2026 | Zago Wagner M.officer: Chief Scientific Officer | Option | 51,000 | — |
| Jul 30, 2026 | Swanson Chad J.officer: Chief Development Officer | Tax | 3,467 | $8.56 |
| Jul 30, 2026 | Kingston Anne Evansofficer: Chief Strategy Officer | Tax | 3,498 | $8.56 |
| Jul 30, 2026 | Walker Karin Lofficer: Chief Accounting Officer | Option | 15,000 | — |
| Jul 30, 2026 | Kingston Anne Evansofficer: Chief Strategy Officer | Sell | 7,662 | $8.47 |
| Jul 30, 2026 | Nguyen Tranofficer: Chief Strategy Officer and CFO | Option | 57,000 | — |
| Jul 30, 2026 | Swanson Chad J.officer: Chief Development Officer | Option | 51,000 | — |
| Jul 30, 2026 | Kinney Gene G.director, officer: President and CEO | Option | 84,000 | — |
| Jul 30, 2026 | Smith Brandon S.officer: Chief Operating Officer | Option | 78,000 | — |
| Jul 30, 2026 | Isaacs Michael Johnofficer: General Counsel & Company Sec. | Tax | 4,694 | $8.56 |
| Jun 18, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 20,000 | $7.90 |
| Jun 12, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 125,000 | $8.17 |
| Jun 5, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 50,000 | $9.31 |
| Jun 3, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 50,000 | $9.43 |
| May 26, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 100,000 | $9.81 |
| May 15, 2026 | Ekman Larsdirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | Dunn William H. Jr.director | Grant | 27,000 | $9.76 |
| May 15, 2026 | WELCH DANIEL Gdirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | Selkoe Dennis J.director | Grant | 27,000 | $9.76 |
| May 15, 2026 | Cooke Shanedirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | COLLIER RICHARD Tdirector | Grant | 27,000 | $9.76 |
| Apr 10, 2026 | Kingston Anne Evansofficer: Chief Strategy Officer | Grant | 100,000 | $10.50 |
| Mar 5, 2026 | Malecek Michael Jofficer: Chief Legal Officer | Grant | 190,000 | $9.36 |
| Mar 5, 2026 | Kinney Gene G.director, officer: President and CEO | Grant | 520,000 | $9.36 |
| Mar 5, 2026 | Smith Brandon S.officer: Chief Operating Officer | Grant | 190,000 | $9.36 |
| Mar 5, 2026 | Walker Karin Lofficer: Chief Accounting Officer | Grant | 150,000 | $9.36 |
Source: PRTA SEC Form 4 filings, latest Aug 21, 2026. For informational purposes only — not investment advice.
Institutional activity (13F)
How institutions changed their PRTA positions over the last 6 months (SEC Form 13F).
Increased
125
New positions
60
Reduced
113
Sold out
21
Largest moves
| Institution | Action | Shares | Filed |
|---|---|---|---|
| FMR LLC | Unchanged | 7.6M | May 15, 2026 |
| FMR LLC | Reduced | 7.2M | Aug 13, 2026 |
| RUBRIC CAPITAL MANAGEMENT LP | Increased | 5.0M | May 15, 2026 |
| Rubric Capital Management LP | Unchanged | 5.0M | Aug 14, 2026 |
| BlackRock, Inc. | Increased | 4.9M | Aug 7, 2026 |
| BLACKROCK, INC. | Increased | 4.6M | May 13, 2026 |
| STATE STREET CORP | Increased | 2.4M | Aug 7, 2026 |
| ACADIAN ASSET MANAGEMENT LLC | Increased | 2.0M | Aug 13, 2026 |
| STATE STREET CORP | Reduced | 1.9M | May 15, 2026 |
| D. E. SHAW & CO., INC. | Increased | 1.8M | May 15, 2026 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | Increased | 1.7M | Aug 13, 2026 |
| D. E. Shaw & Co., Inc. | Reduced | 1.6M | Aug 14, 2026 |
| ADAR1 CAPITAL MANAGEMENT, LLC | Reduced | 1.6M | May 18, 2026 |
| ADAR1 Capital Management, LLC | Reduced | 1.6M | Aug 14, 2026 |
| ACADIAN ASSET MANAGEMENT LLC | Increased | 1.5M | May 13, 2026 |
Source: SEC Form 13F filings. For informational purposes only — not investment advice.