Ranked by reported Q1 2026 13F market value
Share of total reported institutional value in PRTA held by the largest 10 / 25 filers.
| # | Institution | Shares Held | Market Value | QoQ Change | Ownership % | % of Fund |
|---|---|---|---|---|---|---|
| 1 | FMR LLC | 7.6M | $73.4M | 0.0% | 14.424% | 0.00% |
| 2 | Rubric Capital Management LP | 5.0M | $48.6M | +36.0% | 9.551% | 0.60% |
| 3 | BlackRock, Inc. | 4.6M | $45.1M | +13.1% | 8.871% | 0.00% |
| 4 | STATE STREET CORP | 1.9M | $18.8M | -14.5% | 3.703% | 0.00% |
| 5 | D. E. Shaw & Co., Inc. | 1.8M | $17.1M | +4.9% | 3.368% | 0.02% |
| 6 | ADAR1 Capital Management, LLC | 1.6M | $15.4M | +8.5% | 3.021% | 0.96% |
| 7 | VANGUARD PORTFOLIO MANAGEMENT LLC | 1.4M | $14.1M | — | 2.762% | 0.00% |
| 8 | MORGAN STANLEY | 1.2M | $12.0M | -1.3% | 2.350% | 0.00% |
| 9 | Palo Alto Investors LP | 1.2M | $11.7M | -8.5% | 2.308% | 1.80% |
| 10 | TWO SIGMA INVESTMENTS, LP | 1.2M | $11.7M | +80.0% | 2.304% | 0.01% |
| 11 | GEODE CAPITAL MANAGEMENT, LLC | 1.1M | $10.7M | +3.3% | 2.098% | 0.00% |
| 12 | FEDERATED HERMES, INC. | 1.1M | $10.3M | +8.8% | 2.024% | 0.02% |
| 13 | JACOBS LEVY EQUITY MANAGEMENT, INC | 972K | $9.4M | -0.6% | 1.857% | 0.04% |
| 14 | GOLDMAN SACHS GROUP INC | 819K | $8.0M | -12.4% | 1.564% | 0.00% |
| 15 | DIMENSIONAL FUND ADVISORS LP | 783K | $7.6M | +0.9% | 1.495% | 0.00% |
| 16 | Nuveen, LLC | 759K | $7.4M | +0.0% | 1.451% | 0.00% |
| 17 | Qube Research & Technologies Ltd | 615K | $6.0M | +50.7% | 1.174% | 0.01% |
| 18 | RENAISSANCE TECHNOLOGIES LLC | 608K | $5.9M | +39.5% | 1.160% | 0.01% |
| 19 | CITADEL ADVISORS LLC | 573K | $5.6M | -46.8% | 1.094% | 0.00% |
| 20 | Mariner, LLC | 563K | $5.5M | -2.6% | 1.076% | 0.01% |
| 21 | MONIMUS CAPITAL MANAGEMENT, LP | 486K | $4.7M | +91.1% | 0.928% | 1.31% |
| 22 | VANGUARD CAPITAL MANAGEMENT LLC | 484K | $4.7M | — | 0.925% | 0.00% |
| 23 | Rangeley Capital, LLC | 449K | $4.4M | -14.3% | 0.859% | 4.63% |
| 24 | Birchview Capital, LP | 449K | $4.4M | +1.8% | 0.858% | 2.48% |
| 25 | ARMISTICE CAPITAL, LLC | 439K | $4.3M | -70.7% | 0.839% | 0.13% |
denotes a marquee investor (Buffett, Burry, ARK, Tiger Global, Pershing Square, Baupost and other widely-followed managers). “% of Fund” shows how much of that investor’s total 13F portfolio is invested in PRTA — a direct measure of their conviction.
Filings activity in PRTA during Q1 2026, grouped by how each filer changed its position.
8 quarters of 13F filings · Δ columns show change vs prior quarter
| Quarter | Inst. Holders | Δ Holders | Ownership % | Δ Ownership | Total 13F Value | Δ Value |
|---|---|---|---|---|---|---|
| Q1 2026 | 179 | +1.7% | 102.60% | 0.36 pp | $443M | 0.3% |
| Q4 2025 | 176 | 3.8% | 102.96% | +8.10 pp | $445M | +8.5% |
| Q3 2025 | 183 | 0.5% | 94.86% | +39.06 pp | $410M | +70% |
| Q2 2025 | 184 | +17% | 55.80% | 82.37 pp | $241M | 60% |
| Q1 2025 | 157 | 4.8% | 138.17% | 21.08 pp | $597M | 13% |
| Q4 2024 | 165 | +3.1% | 159.25% | 21.56 pp | $688M | 12% |
| Q3 2024 | 160 | +1.3% | 180.81% | 19.18 pp | $781M | 18% |
| Q2 2024 | 158 | — | 199.99% | — | $948M | — |
Source: SEC 13F institutional filings. Ownership % requires market cap data and will show once linked. Δ columns compare to the immediately prior filed quarter.
Quick answers to the most common questions about buying PRTA stock.
Based on Q1 2026 13F filings, institutional ownership of Prothena Corporation plc stands at 102.6%, held across 179 reporting institutions.
FMR LLC is the largest reported institutional holder of PRTA, with approximately 7,551,218 shares worth $0.07B as of Q1 2026.
Yes — 3 widely-followed marquee investors appear among the top 25 institutional holders of PRTA, including TWO SIGMA INVESTMENTS, LP, RENAISSANCE TECHNOLOGIES LLC, CITADEL ADVISORS LLC.
Our composite Smart Money Score for PRTA is 57 out of 100 (Neutral). It combines net institutional buying activity, ownership shift, marquee investor presence, and holder-count growth.
30 institutions opened new positions in PRTA during Q1 2026, while 27 fully exited. 104 added to existing positions and 43 trimmed.
PRTA institutional ownership fell by 0.36 percentage points quarter-over-quarter, with a net change of +3 holders.
The top 10 institutions account for 60.5% of all reported 13F value in PRTA, and the top 25 account for 82.7%.
All data is sourced from SEC Form 13F filings, which institutional investment managers with at least $100M in assets are required to file each quarter. We process every 13F filing from EDGAR and recompute the aggregates after each cycle. Insider transactions are sourced from Form 4 filings.
Prothena Corporation plc (PRTA) Institutional Ownership