Prothena Ownership | Who Owns Prothena?
Prothena Ownership Summary
Prothena is owned by 24.10% institutional investors, 19.20% insiders, and 56.71% retail investors. Fmr is the largest institutional shareholder, holding 14.68% of PRTA shares. Vanguard Health Care Inv is the top mutual fund, with 7.77% of its assets in Prothena shares.
PRTA Ownership Benchmark
| Type | Name | % Inst | % Insiders | % Retail |
|---|---|---|---|---|
| Stock | Prothena | 24.10% | 19.20% | 56.71% |
| Sector | Healthcare Stocks | 232.01% | 10.74% | -142.75% |
| Industry | Biotech Stocks | 381.47% | 10.55% | -292.02% |
Institutional Shareholders
Top Institutional Shareholders by Total Shares
| Holder | Shares | % Holding | Value |
|---|---|---|---|
| Fmr | 7.90M | 14.68% | $77.12M |
| Blackrock funding, inc. /de | 4.11M | 7.63% | $39.23M |
| Blackrock | 3.86M | 7.18% | $79.61M |
| Rubric capital management lp | 3.68M | 6.83% | $35.12M |
| Vanguard group | 2.14M | 3.98% | $20.45M |
| Armistice capital | 1.82M | 3.39% | $17.80M |
| Adar1 capital management | 1.47M | 2.73% | $14.34M |
| Acadian asset management | 1.44M | 2.67% | $13.72M |
| Palo alto investors lp | 1.32M | 2.46% | $12.92M |
| Morgan stanley | 1.25M | 2.32% | $11.91M |
Top Institutional Shareholders by % of Total Assets
| Holder | Shares | % Assets | Value |
|---|---|---|---|
| Rangeley capital | 560.46K | 4.73% | $5.47M |
| Birchview capital, lp | 549.02K | 4.05% | $5.36M |
| Palo alto investors lp | 1.32M | 2.39% | $12.92M |
| Monimus capital management, lp | 258.06K | 1.55% | $2.52M |
| Adar1 capital management | 1.47M | 1.35% | $14.34M |
| Sandia investment management lp | 29.95K | 0.87% | $292.31K |
| Boxer capital | 690.00K | 0.75% | $14.24M |
| Artal group | 1.00M | 0.53% | $20.67M |
| Dcf advisers | 195.75K | 0.50% | $1.87M |
| Rubric capital management lp | 3.68M | 0.42% | $35.12M |
Top Buyers
| Holder | Shares | % Assets | Change |
|---|---|---|---|
| Rubric capital management lp | 3.68M | 0.42% | 2.14M |
| Arrowstreet capital, limited partnership | 654.29K | 0.00% | 654.29K |
| Point72 asset management | 646.75K | 0.01% | 646.75K |
| Goldman sachs group | 935.33K | 0.00% | 582.11K |
| Balyasny asset management | 575.79K | 0.01% | 575.79K |
Top Sellers
| Holder | Shares | % Assets | Change |
|---|---|---|---|
| Ecor1 capital | - | - | -11.58M |
| Adar1 capital management | 1.47M | 1.35% | -1.91M |
| Siren | - | - | -1.28M |
| Finepoint capital lp | - | - | -640.07K |
| Jpmorgan chase | 169.96K | 0.00% | -565.81K |
New Positions
| Holder | Shares | % Assets | Change | Value |
|---|---|---|---|---|
| Arrowstreet capital, limited partnership | 654.29K | 0.00% | 654.29K | $6.39M |
| Point72 asset management | 646.75K | 0.01% | 646.75K | $6.31M |
| Jump financial | 186.25K | 0.02% | 186.25K | $1.82M |
| Campbell & co investment adviser | 94.16K | 0.04% | 94.16K | $899.18K |
| Norges bank | 57.45K | 0.00% | 57.45K | $795.74K |
Sold Out
| Holder | Change |
|---|---|
| Truvestments capital | -1.00 |
| Koesten, hirschmann & crabtree | -1.00 |
| Jfs wealth advisors | -2.00 |
| Cypress capital | -2.00 |
| Cbiz investment advisory services | -2.00 |
Institutional Ownership Trends
| Date | Holdings | Change % | Shares | Change % | Ownership | Change % | Increased Position | Change % | Decreased Position | Change % |
|---|---|---|---|---|---|---|---|---|---|---|
| Dec 31, 2025 | 80 | -60.00% | 12,971,151 | -69.58% | 24 | 0.38% | 30 | -67.39% | 25 | -58.33% |
| Sep 30, 2025 | 79 | -60.70% | 11,520,268 | -72.42% | 21 | 0.36% | 36 | -66.67% | 20 | -51.22% |
| Jun 30, 2025 | 198 | 17.86% | 41,726,109 | -20.15% | 77 | 0.82% | 107 | 81.36% | 41 | -33.87% |
| Mar 31, 2025 | 6 | -96.69% | 2,463,987 | -95.40% | 4 | 0.05% | 2 | -98.06% | 4 | -88.89% |
| Dec 31, 2024 | 107 | -35.93% | 25,474,325 | -49.96% | 47 | 0.53% | 63 | -12.50% | 19 | -57.78% |
Top Mutual Funds Shareholders
| Holder | Shares | % Holding | Change |
|---|---|---|---|
| Vanguard Health Care Inv | 4.18M | 7.77% | -39.90K |
| Fidelity Growth Compy Commingled Pl S | 3.42M | 6.35% | 11.46K |
| Fidelity Growth Compy Commingled Pl O | 3.28M | 6.09% | 1.22K |
| Fidelity Growth Company Fund | 2.29M | 4.26% | -12.93K |
| T. Rowe Price New Horizons | 1.64M | 3.04% | -251.35K |
| US Small-Cap Growth II Equity Comp | 1.64M | 3.04% | -251.90K |
| State Street® SPDR® S&P® Biotech ETF | 1.41M | 2.63% | -7.62K |
| iShares Russell 2000 ETF | 1.07M | 1.98% | 294.51K |
| Fidelity Series Growth Company | 758.90K | 1.41% | - |
| Nuveen Quant Small Cap Equity R6 | 652.13K | 1.21% | -5.64K |
Recent Insider Transactions
| Date | Name | Role | Activity | Value |
|---|---|---|---|---|
| May 06, 2025 | EcoR1 Capital, LLC | - | Sell | $15.16M |
| May 05, 2025 | EcoR1 Capital, LLC | - | Sell | $7.93M |
| May 02, 2025 | EcoR1 Capital, LLC | - | Sell | $27.74M |
| Dec 31, 2024 | SCULLY WILLIAM P | - | Buy | $389.64K |
| Dec 18, 2024 | SCULLY WILLIAM P | - | Buy | $1.02M |
Insider Transactions Trends
| Date | Buy | Sell |
|---|---|---|
| 2026 Q1 | - | - |
| 2025 Q3 | - | - |
| 2025 Q2 | - | 3 |
| 2025 Q1 | 1 | - |
| 2024 Q4 | - | - |
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