# Prothena share price today (Prothena Corporation plc, PRTA)

> Prothena Corporation plc's share price, valuation and earnings point in different directions. The next one or two quarters should make it clearer. PRTA · Healthcare · Biotechnology · data as of 4 November 2026. Page: https://www.sectoralpha.in/us/stocks/prta

Sector Alpha also publishes a daily newsletter that explains one Indian stock at a time: https://newsletter.sectoralpha.in/?utm_source=sectoralpha&utm_medium=ai_text&utm_campaign=llms

## Key numbers

- Price: $8.39 (−20.5% in a year)
- Revenue (Jun 2026): ₹0.0 B
- Profit (Jun 2026), incl. one-off: ₹0.0 B (one-off item, see below)
- ROE: −87%, FY25

Biggest thing to watch: the price is not yet in a clear uptrend, so timing is the risk more than the business. ## What is the Prothena share price today? Prothena Corporation plc's share price was $8.39 at the close on 4 November 2026. That is 9.0% below its average price over the last 200 trading days. In the last 52 weeks it traded between $8 and $11, and at that close it sat 9% of the way up from that low. Over the past 13 weeks it has done better than the S&P 500, and it has stayed ahead for 2 weeks in a row. Over the last 1 year the share price moved +31% while the S&P 500 moved +18%, so it is ahead of the index over that whole period. The chart above shows the 13-week comparison for every week. This page treats a rise as over when the price closes below its 200-day average on two Fridays in a row. ## What dividend does Prothena pay? Prothena Corporation plc pays no dividend. In the last 12 reported quarters it declared no dividend per share, so there is no payout history to chart and no yield to show. Companies like this usually keep their earnings in the business, so the cash-flow sections show where that cash goes. ## Which stock lists is Prothena on? Prothena is not in the Nasdaq 100, the S&P 500 or the Dow Jones 30, and is not on the US tech stocks list. ## Is Prothena profitable? Prothena Corporation plc posted a net loss of ₹0.02 B in the Jun 2026 quarter. That quarter includes a one-off gain bigger than its revenue, so the comparison with last year does not reflect normal business. The full FY25 year was a loss of ₹0.2 B. That loss is 1,839.9% of the quarter's revenue. The same quarter a year earlier lost ₹0.1 B. 9 of the last 12 reported quarters were loss-making. Jun 2026 profit was ₹0.0 B. Read this profit with care: at ₹0.0 B it is bigger than the quarter's whole revenue of ₹0.0 B. No business earns more than it takes in from sales, so this is a one-off item (for example a debt settlement, a tax write-back or an asset sale), not money the business earned. The underlying business is running at a −1,850.2% operating margin. The jump on last year, and any P/E built on this profit, come from the one-off, not from a real turn in earnings. This company reports in its home currency, not US dollars, so the money charts are left out here. The figures in the text are in that currency (₹); nothing is converted. ## How much revenue does Prothena make, and is it growing? Prothena Corporation plc reported ₹0.0 B of revenue in the Jun 2026 quarter, −77.1% on the same quarter a year earlier. Over 4 years it has grown −53.1% a year on average. The last full year, FY25, came in at ₹0.0 B. The last four reported quarters add to ₹0.1 B. FY25 revenue was ₹0.0 B, −92.8% on the year before. Recent pace: the last four quarters grew +419.8% on average, against −53.1% a year over the longer run, so this year is growing faster than its own long-run rate. Is growth speeding up? Revenue over the last 12 months grew +427.3%, against −49.9% a year over the last 8 quarters (accelerating). This company reports in its home currency, not US dollars, so the money charts are left out here. The figures in the text are in that currency (₹); nothing is converted. ## How much of its sales does Prothena keep? Prothena Corporation plc's sales have fallen to very little: FY25 revenue was ₹0.0 B, against ₹0.2 B in FY21. On sales that small an operating margin is not a useful reading, so this section is left out until sales recover. ## Is Prothena's profit turning into cash? Prothena Corporation plc's cash-flow history is too short to judge how much of its profit turns into cash. In FY25 its operations used ₹0.2 B of cash, against −₹0.2 B of profit. After ₹0.0 B of spending on assets, free cash was −₹0.2 B: it spent more than its operations brought in. Cash-flow figures here are yearly, because quarterly cash statements are not published, so this section changes once a year. What to look at next: it spends almost nothing on new assets, so the cash goes on running the business. The next section shows the spending figures. This company reports in its home currency, not US dollars, so the money charts are left out here. The figures in the text are in that currency (₹); nothing is converted. ## Where does Prothena's cash go? Prothena Corporation plc does not report the customer, stock and supplier day counts a cash cycle needs, so this section looks at its spending on assets instead. It spent ₹0.0 B on assets over the last 3 years. Nothing is estimated in place of the missing day counts, so no cash-cycle chart is drawn. Spending on assets: ₹0.0 B over the last 3 years. In short: almost nothing is being spent on new assets, so the cash goes on running the business. This company reports in its home currency, not US dollars, so the money charts are left out here. The figures in the text are in that currency (₹); nothing is converted. ## What is Prothena's P/E ratio, and how does it compare with its own history? Prothena Corporation plc has no P/E right now, because its earnings are negative. The revenue and margin sections are where a turn would show first. The P/E comes back here once profit turns positive. ## Is the Prothena business getting better or worse? Prothena Corporation plc's business trend cannot be read yet. There are fewer than eight usable quarters of growth figures, so there is not enough history to read the trend. This is based on 12 quarters of 2 measures, with some gaps. Why it matters: with too little history, we say so rather than guess a direction. The latest quarter’s profit includes a one-off item bigger than the normal business, so the profit line is shown but does not count in this reading. One or more growth lines have an extreme jump caused by comparing with a near-zero or loss-making quarter. Those jumps are capped before reading and drawn at the edge of the chart, so one odd quarter does not decide the result. The return figures here are yearly, not quarterly. They show level and direction only; they can support the growth lines but never decide the reading alone. There are fewer than eight usable quarters, so this page does not guess a direction from so little history. ## How much does Prothena earn on its capital? Prothena Corporation plc earned a ROE of −87% in FY25. Its return on capital used (ROIC) is left out: on sales this small it reads −4,796%, a number that says nothing useful about the business. ## Does Prothena have too much debt? Prothena Corporation plc has total debt of ₹0.0 B against shareholder equity of ₹0.3 B as of Jun 2026, so its debt is 0.02× its equity, which is very little. Year by year, that ratio went from 0.03 in FY21 to 0.03 in FY25. So the returns on this page come from the business, not from borrowed money. This company reports in its home currency, not US dollars, so the money charts are left out here. The figures in the text are in that currency (₹); nothing is converted. ## What is the Prothena shareholding pattern? 23.8% of Prothena Corporation plc's tradable shares are in short positions, which are bets that the price will fall, so a large group of traders is betting against it. At normal trading volumes, closing those positions would take about 13.6 days. US companies do not publish a quarter-by-quarter list of owners, so this page uses short interest instead. It is a single reading at one point in time; we do not have its history. Why it is at this level: the figure does not say who holds the short positions or why, so we show the level without guessing the story. ## How far is Prothena from balance-sheet trouble? For Prothena Corporation plc, the Z-score is 13.38. A Z-score above about 3 is safe and below about 1.8 signals danger, so this is well clear of danger. It estimates how far the balance sheet is from trouble; it is not a forecast of failure. Why it matters: a Z-score of 13.38 is well clear of the danger zone, so the balance sheet is not the risk here. ## How does Prothena rank in its industry? There is no score against its industry: Prothena Corporation plc is not among the largest members shown in this industry comparison for Biotechnology. The score ranks a company within its industry: each measure is scored against the other members. Without that group there is no score, so none is shown. ## Which companies is Prothena compared with? No sector comparison is shown here, not among the largest members shown in this industry comparison. ## Which companies are close to Prothena in size? Prothena is the 151st largest of 211 Biotechnology companies on Sector Alpha by market value (scores of 5 November 2026). Just above it: Phathom Pharmaceuticals, Inc., Oculis Holding AG and CorMedix Inc. Just below it: Prelude Therapeutics Incorporated, Editas Medicine, Inc. and Altimmune, Inc. ### Biotechnology companies close in size

1. [Phathom Pharmaceuticals, Inc.](https://www.sectoralpha.in/us/stocks/phat) $451 million
2. [Oculis Holding AG](https://www.sectoralpha.in/us/stocks/ocs) $449 million
3. [CorMedix Inc.](https://www.sectoralpha.in/us/stocks/crmd) $441 million
4. Prothena Corporation plc $431 million
5. [Prelude Therapeutics Incorporated](https://www.sectoralpha.in/us/stocks/prld) $420 million
6. [Editas Medicine, Inc.](https://www.sectoralpha.in/us/stocks/edit) $418 million
7. [Altimmune, Inc.](https://www.sectoralpha.in/us/stocks/alt) $412 million

[All 211 Biotechnology companies, largest first](https://www.sectoralpha.in/us/sectors/biotechnology#all-companies)

### Companies close in size in other industries

1. [Oxford Industries, Inc.](https://www.sectoralpha.in/us/stocks/oxm) $423 million · Apparel Manufacturing
2. [NeuroPace, Inc.](https://www.sectoralpha.in/us/stocks/npce) $423 million · Medical Devices
3. Prothena Corporation plc $421 million
4. [AdvanSix Inc.](https://www.sectoralpha.in/us/stocks/asix) $421 million · Chemicals
5. [RE/MAX Holdings, Inc.](https://www.sectoralpha.in/us/stocks/rmax) $419 million · Real Estate Services

## What else do people ask about Prothena? ### What were Prothena's latest quarterly results? Prothena Corporation plc reported revenue of ₹0.0 B and a net loss of ₹0.0 B for the Jun 2026 quarter. The operating margin was −1,850.2%, 673.6 percentage points lower than a year earlier (as of 4 November 2026). ### What is Prothena's market cap? Prothena Corporation plc's market capitalisation is $431 M at a stock price of $8.39. Market cap is the share price times the number of shares, so it changes whenever the price moves (as of 4 November 2026). ### How is Prothena performing? Prothena Corporation plc's latest readings are below. Over the past 13 weeks it has done better than the S&P 500, for 2 weeks running. This describes what the data did, not a rating (as of 4 November 2026). ### Will Prothena's stock price go up? This page does not forecast Prothena Corporation plc's stock price. What it shows instead: the stock price is $8.39. Nobody can reliably say which way a price will move, and this site does not try (as of 4 November 2026). ### What could break the Prothena story? Biggest thing to watch: the price is not yet in a clear uptrend, so timing is the risk more than the business. On price, this page treats a rise as over when the share price closes below its 200-day average on two Fridays in a row (as of 4 November 2026). ### Is Prothena a stock worth studying right now? What the numbers show: Prothena Corporation plc's share price, valuation and earnings point in different directions. The next one or two quarters should make it clearer. The main open question: the next one or two quarters of results. Every number on this page is worked out by code from the published figures, with no forecasts and no price opinions (as of 4 November 2026). This is research, not advice. We’re not SEBI-registered.