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NASDAQ · Health careProthena Corp Public Ltd Co (PRTA)
Prothena Corp Public Ltd Co brought in $52.7M of revenue over the twelve months to September 30, 2026, up 347.4% from a year earlier. It posted a net loss of $24M. At September 30, 2026 it held $271.4M in cash. Its latest periodic report to the SEC is the quarterly report (10-Q) filed on November 5, 2026.
Key facts about Prothena Corp Public Ltd Co
- Net worth
- Prothena Corp Public Ltd Co has a market value (market cap) of $439.4M at the latest share price, and shareholders' equity of $268.8M on its balance sheet at September 30, 2026. A company's "net worth" usually means one of these: what the market pays for all its shares, or its assets minus its liabilities.
- Revenue and profit
- In fiscal 2025 revenue was $9.7M (-92.8% year on year), with a net loss of $244.1M. Over the 12 months to September 30, 2026: revenue $52.7M, net loss $24M.
- Cash flow
- In fiscal 2025 operations used $163.6M of cash.
- Latest report
- The latest periodic report (quarterly report, 10-Q) was filed with the SEC on November 5, 2026 and covers the period to September 30, 2026. Open on SEC EDGAR
- Next earnings report
- Prothena Corp Public Ltd Co's next report is expected around February 18, 2027. That is an estimate from its filing rhythm, not a date the company has announced.
What Prothena Corp Public Ltd Co does
Prothena Corp Public Ltd Co is registered with the SEC under industry code SIC 2834 (Pharmaceutical Preparations). Its shares trade on NASDAQ under the ticker PRTA.
Revenue and profit by year
Key figures
| Fiscal year | Revenue | Net income | Diluted EPS | Free cash flow |
|---|---|---|---|---|
| 2025 | $9.7M | -$244.1M | -$4.53 | n/a |
| 2024 | $135.2M | -$122.3M | -$2.27 | n/a |
| 2023 | $91.4M | -$147M | -$2.76 | n/a |
| 2022 | $53.9M | -$116.9M | -$2.47 | n/a |
| 2021 | $200.6M | $67M | $1.38 | n/a |
| 2020 | $853K | -$111.1M | -$2.78 | n/a |
Earnings: every quarter and the next report date
Full financial statements: income, balance sheet and cash flow
Where PRTA ranks in Health care
Latest SEC filings
What Prothena Corp Public Ltd Co has filed recently, newest first. Each links to the original document on SEC EDGAR.
- November 5, 2026Quarterly report 10-Q · period to September 30, 2026Revenue fell 74% to $620K versus the same quarter last year; diluted EPS -$0.32 versus -$0.68.
- November 5, 2026
- October 29, 2026
- October 2, 2026Executive or director change8-KProthena Chief Development Officer Chad J. Swanson has resigned effective October 9, 2026, to join a strategic partner.
- August 19, 2026Passive stake changed SCHEDULE 13G/A
- August 14, 2026Passive stake changed SCHEDULE 13G/A
- August 6, 2026Quarterly report 10-Q · period to June 30, 2026Revenue fell 77% to $1M versus the same quarter last year; diluted EPS -$0.36 versus -$2.34.
- August 6, 2026
- August 6, 2026Passive stake changed SCHEDULE 13G/A
- July 29, 2026Passive stake changed SCHEDULE 13G/A
Insider trades
What the people running Prothena Corp Public Ltd Co did with its shares, from the Form 4 filings they must send the SEC within two business days.
Insiders bought $8.7M worth of shares on the open market in the last 90 days and sold none.
| Date | Insider | What | Shares | Value |
|---|---|---|---|---|
| October 27, 2026 | Scully William P10% owner | Gave as a gift | 566,444 | - |
| October 23, 2026 | Scully William P10% owner | Bought | 50,000 | $403.5K |
| October 22, 2026 | Scully William P10% owner | Bought | 100,000 | $818.5K |
| October 14, 2026 | Scully William P10% owner | Bought | 10,000 | $84.6K |
| October 13, 2026 | Scully William P10% owner | Bought | 100,000 | $835.5K |
| October 8, 2026 | Scully William P10% owner | Boughtindirect | 90,000 | $770.9K |
| October 7, 2026 | Scully William P10% owner | Boughtindirect | 125,000 | $1.1M |
| October 2, 2026 | Scully William P10% owner | Boughtindirect | 100,000 | $857.2K |
Who owns PRTA
Three views from three kinds of SEC filings, each with its own date. They overlap and are not added up.
5% holders
| Holder | Of class | Filed |
|---|---|---|
| Fmr LLC13G, passive with 1 related filers | 13.8% | August 6, 2026 |
| Scully William P13G, passive | 10.3% | May 11, 2026 |
| Fennell Todd W.13G, passive | 10.2% | August 19, 2026 |
| Rubric Capital Management LP13G, passive with 1 related filers | 9.29% | May 15, 2026 |
| William P. Scully13G, passive | 7.5% | November 13, 2024 |
| Todd W. Fennell13G, passive | 5.89% | November 13, 2024 |
Largest institutional holders
Positions that investment managers reported on Form 13F for the quarter ended June 30, 2026, largest first, with the change on the quarter ended March 31, 2026. Managers file 13F up to 45 days after a quarter ends. 188 managers reported a position.
| Holder | Shares | Change on quarter |
|---|---|---|
| Fmr LLC | 7,199,218 | -352,000 |
| Rubric Capital Management LP | 5,000,000 | 0 |
| BlackRock, Inc. | 4,867,955 | +223,795 |
| State Street Corp | 2,393,424 | +454,926 |
| Vanguard Portfolio Management LLC | 1,651,293 | +205,314 |
| D. E. Shaw & Co., Inc. | 1,611,457 | -151,890 |
| ADAR1 Capital Management, LLC | 1,554,535 | -26,908 |
| Two Sigma Investments, LP | 1,264,987 | +59,009 |
| Palo Alto Investors LP | 1,143,155 | -65,413 |
| Geode Capital Management, LLC | 1,125,877 | +27,711 |
| Federated Hermes, Inc. | 1,084,401 | +24,552 |
| Morgan Stanley | 995,348 | -235,100 |
| Goldman Sachs Group Inc | 979,730 | +160,845 |
| Jacobs Levy Equity Management, Inc | 965,988 | -6,029 |
| Dimensional Fund Advisors LP | 905,651 | +123,048 |
| Qube Research & Technologies Ltd | 791,169 | +176,566 |
| Renaissance Technologies LLC | 697,615 | +90,100 |
| Man Group plc | 678,116 | +296,542 |
| Mariner, LLC | 625,095 | +62,013 |
| Nuveen, LLC | 557,157 | -202,211 |
Insiders
9 insiders reported holding 2,619,702 shares in total, about $22.4M at the last price.
| Holder | Shares |
|---|---|
| Scully William P10% owner | 2,282,444529,000 held indirectly |
| Kinney Gene G.President and CEO, Director | 68,793 |
| Kingston Anne EvansChief Strategy Officer | 55,782 |
| Smith Brandon S.Chief Operating Officer | 52,000 |
| Swanson Chad J.Chief Development Officer | 40,733 |
| Nguyen TranChief Strategy Officer and CFO | 40,205 |
| Isaacs Michael JohnGeneral Counsel & Company Sec. | 35,745 |
| Zago Wagner M.Chief Scientific Officer | 34,000 |
| Walker Karin LChief Accounting Officer | 10,000 |
Questions about PRTA
What does Prothena Corp Public Ltd Co do?
Prothena Corp Public Ltd Co is a company in the Health care sector, listed on NASDAQ as PRTA. Its shares trade on NASDAQ under the ticker PRTA.
What is Prothena Corp Public Ltd Co's net worth?
Prothena Corp Public Ltd Co has a market value (market cap) of $439.4M at the latest share price, and shareholders' equity of $268.8M on its balance sheet at September 30, 2026. A company's "net worth" usually means one of these: what the market pays for all its shares, or its assets minus its liabilities.
Is Prothena Corp Public Ltd Co profitable?
No. Over the twelve months to September 30, 2026 it reported a net loss of $24M on revenue of $52.7M.
How much revenue does Prothena Corp Public Ltd Co make?
Over the twelve months to September 30, 2026 Prothena Corp Public Ltd Co reported revenue of $52.7M. That is 347.4% more than a year earlier.
When did Prothena Corp Public Ltd Co last report?
Its most recent periodic report is the quarterly report (10-Q) filed on November 5, 2026. It covers the period to September 30, 2026.
When is Prothena Corp Public Ltd Co's next earnings report?
Prothena Corp Public Ltd Co's next report is expected around February 18, 2027. That is an estimate from its filing rhythm, not a date the company has announced.
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Where the numbers come from
Financial figures are the values Prothena Corp Public Ltd Co tagged in its own SEC filings (XBRL), taken from the latest filing for each period, so restatements replace older figures. Revenue, profit and cash flow are for full fiscal years unless marked as the last twelve months, which is the sum of the four most recent quarters. Where a company reports only the full year, the fourth quarter is the year minus the first three.
Prices are delayed end-of-day market data in the listing currency, and market cap moves with the price. P/E is shown only when earnings per share are positive. Nothing here is investment advice.