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.

A share price tends to move through four phases: moving sideways (stage 1), rising (stage 2), stalling near a high (stage 3) and falling (stage 4). The phase helps read everything below.

Over the past 13 weeks it has done worse than the S&P 500, and it has been behind for 1 week running.

Over the last 1 year the share price moved +31% while the S&P 500 moved +23%, so it is ahead of the index over that whole period. It was last ahead over 13 weeks in the week of 30 October 2026. 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.

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.

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.

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.

Net profit is what is left after every cost, interest and tax. Earnings per share, dividends and book value all grow from it.

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.

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.

Revenue is everything the company billed its customers in the period.

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.

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.

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.

The profit and loss account shows what was earned. The cash-flow statement shows the cash that actually came in. Comparing operating cash flow with profit is one of the best checks that a profit is real.

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.

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.

Working capital is the cash tied up between paying suppliers and getting paid. Debtor days: how long customers take to pay. Inventory days: how long stock sits. The cash cycle: the whole loop, in days of sales.

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.

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.

P/E is the share price divided by a year's profit per share: how many rupees the market pays for each rupee of yearly profit.

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.

Every business is somewhere on a path of getting better or worse, and this section names where. The last 12 quarters of growth in revenue, profit and earnings per share, plus the return the business earns on its capital, are read as lines. Getting worse: the lines are falling. Turning around: a low point has just formed and the last few quarters are rising from it. Getting better: the rise from the low has lasted. Growing steadily: steady growth with healthy returns. Slowing from a peak: still high, but slowing. When the lines disagree the result is mixed; too little history means no reading. CAGR (compound annual growth rate) is the steady yearly rate that would turn the starting value into the latest one. It is the fairest way to compare growth over different periods. If the 1-year figure is much bigger than the 10-year one, recent growth is running faster than the long-run trend. A dash means there is no figure for that period, or the starting year was a loss, where a growth rate means nothing.

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.

Compound annual growth rate (%)

Compound annual growth rate over each period, %. Revenue, profit and EPS come from yearly figures; the stock price row is price growth over the same periods. A dash means no figure for that period, or the starting year was a loss.

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.

Return on equity (ROE) is the profit the business earns on its shareholders’ money. We do not have the full capital split, so ROE is the longest history we can draw here.

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.

Debt-to-equity shows how much of the business is paid for with borrowed money. Lower is safer, and the direction matters as much as the level.

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.

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.

There is no quarter-by-quarter list of owners here, so we look at short interest: the share of tradable shares held in short positions, which gain if the price falls.

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 has the short positions or why, so we show the level without guessing the story.

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.

The Z-score estimates how far a company is from balance-sheet trouble. Above about 3 is safe; below about 1.8 is the danger zone. It was built for manufacturers, so it is not used for banks and lenders.

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.

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.

No sector comparison is shown here, not among the largest members shown in this industry comparison.

Prothena is the 151st largest of 211 Biotechnology companies on Sector Alpha by market value (scores of 4 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

148. Phathom Pharmaceuticals, Inc. $451 million
149. Oculis Holding AG $449 million
150. CorMedix Inc. $441 million
151. Prothena Corporation plc $431 million
152. Prelude Therapeutics Incorporated $420 million
153. Editas Medicine, Inc. $418 million
154. Altimmune, Inc. $412 million

All 211 Biotechnology companies, largest first

Companies close in size in other industries

2949. Oxford Industries, Inc. $423 million · Apparel Manufacturing
2950. NeuroPace, Inc. $423 million · Medical Devices
2951. Prothena Corporation plc $421 million
2952. AdvanSix Inc. $421 million · Chemicals
2953. RE/MAX Holdings, Inc. $419 million · Real Estate Services

Sector Alpha, written by code from the published numbers. Data as of 4 November 2026.

Every chart on this page is drawn by code from the published figures, with no forecasts and no price opinions.

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