PROTHENA CORP PLC (PRTA)
Institutional ownership reported to the SEC as of Q2 2026, across 32 quarters.
Institutions report 47,322,534 shares against 51,336,974 outstanding. Shares only - option lines are excluded, which is why this can be compared with the company at all. The count comes from the cover page of the company's own most recent report, so it is dated when that was filed rather than at quarter end. A figure this high can overstate: where an adviser and a sub-adviser both report the same shares, both are counted.
Calls and puts are the parts of reported value carried in derivative lines rather than shares, and they point in opposite directions: a manager holding calls is positioned for the security, one holding puts against it - or hedging shares they already own, which is why index funds carry so many. Most sites add the two together and report one figure, which averages away the only interesting part.
Holders
| Filer | Value | Shares | Their book | Held | Change |
|---|---|---|---|---|---|
| FMR LLC | $70.5M | 7,199,218 | 0.00% | 31q | -4.7%-$3.4M |
| Rubric Capital Management LP | $49.0M | 5,000,000 | 0.45% | 4q | HELD |
| BlackRock, Inc. | $47.7M | 4,867,955 | 0.00% | 8q | +4.8%+$2.2M |
| STATE STREET CORP | $23.4M | 2,393,424 | 0.00% | 31q | +23.5%+$4.5M |
| ACADIAN ASSET MANAGEMENT LLC | $19.7M | 2,010,645 | 0.02% | 5q | +29.9%+$4.5M |
| VANGUARD PORTFOLIO MANAGEMENT LLC | $16.2M | 1,651,293 | 0.00% | 2q | +14.2%+$2.0M |
| D. E. Shaw & Co., Inc. | $15.8M | 1,611,457 | 0.01% | 6q | -8.6%-$1.5M |
| ADAR1 Capital Management, LLC | $15.2M | 1,554,535 | 0.70% | 5q | -1.7%-$263.4K |
| TWO SIGMA INVESTMENTS, LP | $12.4M | 1,264,987 | 0.01% | 9q | +4.9%+$577.7K |
| Palo Alto Investors LP | $11.2M | 1,143,155 | 1.55% | 31q | -5.4%-$640.4K |
| GEODE CAPITAL MANAGEMENT, LLC | $11.0M | 1,125,877 | 0.00% | 31q | +2.5%+$271.4K |
| FEDERATED HERMES, INC. | $10.6M | 1,084,401 | 0.02% | 9q | +2.3%+$240.4K |
| MORGAN STANLEY | $9.7M | 995,348 | 0.00% | 35q | -19.1%-$2.3M |
| GOLDMAN SACHS GROUP INC | $9.6M | 979,730 | 0.00% | 31q | +19.6%+$1.6M |
| JACOBS LEVY EQUITY MANAGEMENT, INC | $9.5M | 965,988 | 0.03% | 6q | -0.6%-$59.0K |
| DIMENSIONAL FUND ADVISORS LP | $8.9M | 905,651 | 0.00% | 31q | +15.7%+$1.2M |
| Qube Research & Technologies Ltd | $7.7M | 791,169 | 0.01% | 5q | +28.7%+$1.7M |
| RENAISSANCE TECHNOLOGIES LLC | $6.8M | 697,615 | 0.01% | 28q | +14.8%+$882.1K |
| Man Group plc | $6.6M | 678,116 | 0.01% | 17q | +77.7%+$2.9M |
| Mariner, LLC | $6.1M | 625,095 | 0.01% | 19q | +11.0%+$607.1K |
| CITADEL ADVISORS LLC | $5.9M incl. $2.5M options CALL+PUT | 338,810 | 0.00% | 31q | -22.2%-$1.7M |
| Nuveen, LLC | $5.5M | 557,157 | 0.00% | 6q | -26.6%-$2.0M |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | $4.8M CALL+PUT | options only | 0.00% | 31q | OPTIONS |
| VANGUARD CAPITAL MANAGEMENT LLC | $4.7M | 479,945 | 0.00% | 2q | -0.9%-$40.9K |
| NORTHERN TRUST CORP | $4.5M | 457,124 | 0.00% | 31q | +23.7%+$857.4K |
| Birchview Capital, LP | $4.4M | 449,019 | 2.06% | 21q | HELD |
| Rangeley Capital, LLC | $4.1M | 417,270 | 3.73% | 5q | -7.2%-$315.1K |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | $3.5M | 355,896 | 0.00% | 31q | HELD |
| MONIMUS CAPITAL MANAGEMENT, LP | $3.2M | 329,052 | 0.75% | 5q | -32.2%-$1.5M |
| BNP PARIBAS FINANCIAL MARKETS | $3.1M | 315,803 | 0.00% | 31q | -25.6%-$1.1M |
| AQR CAPITAL MANAGEMENT LLC | $3.0M | 302,572 | 0.00% | 4q | +48.3%+$964.9K |
| Penbrook Management LLC | $2.7M | 271,720 | 1.70% | 2q | HELD |
| VANGUARD FIDUCIARY TRUST CO | $2.5M | 259,064 | 0.00% | 2q | +1.8%+$44.0K |
| UBS Group AG | $2.4M | 241,425 | 0.00% | 31q | -26.5%-$852.4K |
| MACKENZIE FINANCIAL CORP | $2.3M | 239,899 | 0.00% | new | NEW |
| Coppell Advisory Solutions LLC | $2.3M | 12? | 0.19% | new | |
| GROUP ONE TRADING LLC | $2.2M CALL+PUT | options only | 0.00% | 16q | OPTIONS |
| Squarepoint Ops LLC | $2.2M | 223,971 | 0.00% | 5q | -3.0%-$68.0K |
| BANK OF AMERICA CORP /DE/ | $2.0M | 208,246 | 0.00% | 31q | -47.1%-$1.8M |
| Focused Wealth Management, Inc | $2.0M | 207,445 | 0.18% | 7q | HELD |
| Connor, Clark & Lunn Investment Management Ltd. | $1.9M | 191,693 | 0.00% | 3q | +22.4%+$344.0K |
| MARSHALL WACE, LLP | $1.9M | 190,834 | 0.00% | 3q | +328.1%+$1.4M |
| SIMPLEX TRADING, LLC | $1.6M CALL+PUT | options only | 0.00% | 23q | OPTIONS |
| Quantinno Capital Management LP | $1.6M | 158,331 | 0.00% | 5q | +9.7%+$137.4K |
| JANE STREET GROUP, LLC | $1.5M CALL+PUT | options only | 0.00% | 14q | OPTIONS |
| MILLENNIUM MANAGEMENT LLC | $1.5M CALL | options only | 0.00% | 31q | OPTIONS |
| DIADEMA PARTNERS LP | $1.5M | 149,482 | 0.18% | new | NEW |
| Bank of New York Mellon Corp | $1.3M | 133,906 | 0.00% | 31q | -1.8%-$23.7K |
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ | $1.2M | 126,990 | 0.00% | 7q | -3.8%-$49.5K |
| Assenagon Asset Management S.A. | $1.2M | 125,570 | 0.00% | 4q | +63.6%+$477.8K |
| Russell Investments Group, Ltd. | $1.2M | 121,901 | 0.00% | 11q | +21.1%+$208.3K |
| PRICE T ROWE ASSOCIATES INC /MD/ | $1.1M | 109,252 | 0.00% | 24q | +14.2%+$133.2K |
| Hennion & Walsh Asset Management, Inc. | $888.9K | 90,795 | 0.03% | 7q | +2.5%+$22.0K |
| AMERICAN CENTURY COMPANIES INC | $887.4K | 90,644 | 0.00% | 8q | +13.8%+$107.8K |
| AMERIPRISE FINANCIAL INC | $853.8K | 87,215 | 0.00% | 5q | -2.2%-$19.6K |
| XTX Topco Ltd | $839.2K | 85,717 | 0.01% | 4q | -7.2%-$64.7K |
| Susquehanna Portfolio Strategies, LLC | $809.7K | 82,710 | 0.01% | 5q | +21.9%+$145.3K |
| ExodusPoint Capital Management, LP | $803.0K | 82,023 | 0.01% | 6q | +634.2%+$693.6K |
| MARTINGALE ASSET MANAGEMENT L P | $771.5K | 78,800 | 0.02% | 3q | +14.0%+$95.0K |
| Trexquant Investment LP | $751.2K | 76,731 | 0.00% | 5q | +212.6%+$510.9K |
| DCF Advisers, LLC | $717.1K | 73,247 | 0.13% | 22q | HELD |
| Invesco Ltd. | $699.8K | 71,479 | 0.00% | 31q | +43.5%+$212.2K |
| STATE OF WISCONSIN INVESTMENT BOARD | $688.5K | 70,326 | 0.00% | new | NEW |
| Duncan Williams Asset Management, LLC | $688.1K | 70,281 | 0.16% | 8q | HELD |
| ALLIANCEBERNSTEIN L.P. | $672.8K | 69,217 | 0.00% | 31q | -0.6%-$3.8K |
| Campbell & CO Investment Adviser LLC | $669.1K | 68,345 | 0.04% | 3q | -52.1%-$726.8K |
| Creative Planning | $613.0K | 62,620 | 0.00% | 8q | -14.2%-$101.5K |
| PINNACLE ASSOCIATES LTD | $567.0K | 57,918 | 0.01% | 31q | -4.5%-$26.9K |
| CITIGROUP INC | $566.1K | 57,827 | 0.00% | 31q | +609.5%+$486.3K |
| RHUMBLINE ADVISERS | $547.2K | 55,896 | 0.00% | 31q | +1.0%+$5.2K |
| Schonfeld Strategic Advisors LLC | $492.9K | 50,350 | 0.00% | 2q | +306.1%+$371.5K |
| HSBC HOLDINGS PLC | $492.2K | 49,569 | 0.00% | 8q | -23.8%-$153.9K |
| EDGEWOOD MANAGEMENT LLC | $489.5K | 50,000 | 0.01% | 23q | HELD |
| Quinn Opportunity Partners LLC | $489.5K | 50,000 | 0.02% | 5q | HELD |
| WELLS FARGO & COMPANY/MN | $484.8K | 49,520 | 0.00% | 31q | +81.1%+$217.2K |
| Seven Fleet Capital Management LP | $423.9K | 43,300 | 0.07% | 3q | HELD |
| DEUTSCHE BANK AG\ | $423.6K | 43,270 | 0.00% | 34q | +8.1%+$31.8K |
| PUBLIC EMPLOYEES RETIREMENT SYSTEM OF OHIO | $412.7K | 42,158 | 0.00% | 5q | HELD |
| Engineers Gate Manager LP | $404.0K | 41,270 | 0.01% | new | NEW |
| Rafferty Asset Management, LLC | $395.5K | 40,397 | 0.00% | 3q | -24.2%-$126.0K |
| Virtus Investment Advisers, LLC | $388.3K | 39,660 | 0.09% | 6q | +50.7%+$130.6K |
| SHELTON CAPITAL MANAGEMENT | $386.4K | 39,472 | 0.01% | new | NEW |
| Persistent Asset Partners Ltd | $373.0K | 38,100 | 0.11% | new | NEW |
| BARCLAYS PLC | $368.3K | 37,623 | 0.00% | 31q | -7.9%-$31.7K |
| SEI INVESTMENTS CO | $302.3K | 30,877 | 0.00% | 2q | +79.0%+$133.4K |
| WINTON GROUP Ltd | $298.6K | 30,500 | 0.01% | 2q | -12.1%-$41.1K |
| RBF Capital, LLC | $285.9K | 29,200 | 0.01% | 27q | HELD |
| GREAT LAKES ADVISORS, LLC | $281.3K | 28,733 | 0.00% | 4q | -2.9%-$8.4K |
| PNC Financial Services Group, Inc. | $277.9K | 28,386 | 0.00% | 25q | HELD |
| JPMORGAN CHASE & CO | $265.4K | 26,620 | 0.00% | 31q | +2.5%+$6.5K |
| MetLife Investment Management, LLC | $253.5K | 25,890 | 0.00% | 32q | +32.7%+$62.4K |
| Aquatic Capital Management LLC | $248.9K | 25,419 | 0.01% | new | NEW |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. | $247.3K | 25,174 | 0.00% | 9q | +2.2%+$5.3K |
| Covestor Ltd | $246.0K | 25,190 | 0.14% | 5q | -22.9%-$72.9K |
| Purkiss Capital Advisors LLC | $245.6K | 25,086 | 0.09% | 7q | HELD |
| TUDOR INVESTMENT CORP ET AL | $239.3K | 24,445 | 0.00% | 5q | HELD |
| CANADA PENSION PLAN INVESTMENT BOARD | $235.0K | 24,000 | 0.00% | new | NEW |
| ENVESTNET ASSET MANAGEMENT INC | $224.3K | 22,908 | 0.00% | new | NEW |
| MOGY JOEL R INVESTMENT COUNSEL INC | $203.1K | 20,750 | 0.01% | 5q | HELD |
| PROFUND ADVISORS LLC | $201.4K | 20,570 | 0.01% | 3q | -14.3%-$33.6K |
Showing the largest 100 of 193 reported holders. The count of 192 above leaves out 1 position whose reported value failed our price check; it is listed here as filed.
What the company announced
Form 8-K filings from the last 120 days, showing only the items worth a reader's attention. Earnings releases, exhibit attachments and general disclosures are filed constantly and are left out. Filed is when the SEC received it; event is the date the company says the thing happened.
| Filed | Event date | What | Source |
|---|---|---|---|
| 2026-10-29 | 2026-10-28 | Material agreement terminated | filing |
| 2026-10-02 | 2026-10-02 | Directors or officers departed or appointed | filing |
What the insiders did
Open market purchases and sales reported on Form 4 in the last 180 days. Grants, option exercises and shares surrendered to cover tax are left out: they are compensation rather than a decision to buy or sell. Where a broker filled one order in tranches the lines are summed, because it was one decision.
Ten percent owners and entities
Usually an institution that crossed a reporting threshold, or a company taking a strategic stake, rather than an individual with a view.
| Date | Insider | Role | Side | Shares | Value |
|---|---|---|---|---|---|
| 2026-09-29 | SCULLY WILLIAM P | 10% owner | Bought | 162,000 | $1.4M |
| 2026-10-07 | SCULLY WILLIAM P | 10% owner | Bought | 125,000 | $1.1M |
| 2026-06-11 | SCULLY WILLIAM P | 10% owner | Bought | 125,000 | $1.0M |
| 2026-05-22 | SCULLY WILLIAM P | 10% owner | Bought | 100,000 | $981.3K |
| 2026-09-28 | SCULLY WILLIAM P | 10% owner | Bought | 103,500 | $889.9K |
| 2026-10-02 | SCULLY WILLIAM P | 10% owner | Bought | 100,000 | $857.2K |
Quarter by quarter
Coverage begins with the quarter ending 2018-12-31. Earlier filings exist only as occasional late amendments, too sparse to describe a market, so they are not shown.
| Quarter | Holders | Value | Shares | New | Added | Trimmed | Options |
|---|---|---|---|---|---|---|---|
| Q3 2026 | 29 | $4.6M | 547,819 | 2 | 12 | 5 | 0.0% |
| Q2 2026 | 192 | $477.3M | 47,322,534 | 26 | 54 | 57 | 2.9% |
| Q1 2026 | 188 | $465.6M | 47,280,988 | 26 | 64 | 51 | 1.3% |
| Q4 2025 | 184 | $466.9M | 47,310,528 | 21 | 64 | 53 | 3.2% |
| Q3 2025 | 190 | $445.5M | 43,340,872 | 31 | 55 | 60 | 5.1% |
| Q2 2025 | 195 | $267.2M | 41,871,988 | 54 | 50 | 42 | 4.9% |
| Q1 2025 | 167 | $652.1M | 52,324,461 | 17 | 36 | 56 | 0.7% |
| Q4 2024 | 176 | $758.6M | 53,824,960 | 28 | 57 | 38 | 1.7% |
| Q3 2024 | 164 | $867.7M | 51,390,012 | 22 | 46 | 45 | 0.6% |
| Q2 2024 | 161 | $1.1B | 51,435,794 | 26 | 54 | 42 | 0.4% |
| Q1 2024 | 168 | $1.4B | 55,261,692 | 22 | 54 | 61 | 0.7% |
| Q4 2023 | 195 | $2.1B | 54,766,972 | 35 | 69 | 43 | 6.8% |
| Q3 2023 | 192 | $2.6B | 53,176,814 | 26 | 72 | 50 | 1.1% |
| Q2 2023 | 199 | $3.6B | 51,952,046 | 32 | 70 | 57 | 1.4% |
| Q1 2023 | 192 | $2.9B | 58,642,600 | 27 | 66 | 53 | 0.4% |
| Q4 2022 | 204 | $3.0B | 49,391,867 | 46 | 70 | 55 | 1.2% |
| Q3 2022 | 174 | $2.9B | 46,721,880 | 45 | 46 | 48 | 3.0% |
| Q2 2022 | 147 | $1.3B | 46,809,470 | 15 | 40 | 45 | 1.3% |
| Q1 2022 | 157 | $1.7B | 46,337,429 | 14 | 51 | 51 | 1.1% |
| Q4 2021 | 182 | $2.6B | 52,253,232 | 30 | 69 | 35 | 0.9% |
| Q3 2021 | 181 | $3.8B | 52,629,405 | 47 | 55 | 46 | 0.8% |
| Q2 2021 | 151 | $2.2B | 42,735,244 | 36 | 46 | 40 | 1.1% |
| Q1 2021 | 134 | $3.0B | 120,391,576 | 22 | 32 | 47 | 0.7% |
| Q4 2020 | 125 | $3.0B | 249,854,337 | 24 | 24 | 49 | 0.2% |
| Q3 2020 | 124 | $2.4B | 242,322,757 | 17 | 30 | 50 | 0.2% |
| Q2 2020 | 121 | $2.2B | 206,053,100 | 19 | 34 | 41 | 0.1% |
| Q1 2020 | 111 | $771.3M | 71,791,185 | 9 | 34 | 36 | 0.4% |
| Q4 2019 | 124 | $848.7M | 53,087,889 | 24 | 34 | 35 | 1.0% |
| Q3 2019 | 109 | $426.7M | 54,268,715 | 11 | 29 | 42 | 0.3% |
| Q2 2019 | 114 | $567.6M | 53,542,115 | 21 | 41 | 25 | 0.3% |
| Q1 2019 | 115 | $680.8M | 55,799,575 | 26 | 34 | 27 | 0.6% |
| Q4 2018 | 94 | $602.2M | 56,936,454 | 3 | 1 | 2 | 2.6% |