Prothena Corporation plc PRTA Stock Analysis
- Nasdaq
- Stock
- Market closed · opens Monday 9:30 AM ET
$7.97 up $0.08, 1.01% at close Nov 6
Last close · Previous close $7.89
- Market cap
- $417.26MAt the Nov 6 close
- P/E ratio
- n/mLoss over last 12 months
- Diluted EPS
- −$0.84Last 12 months
- Dividend yield
- NoneLast 12 months
Price chart
$7.97up $0.08, 1.01%Fri, Nov 6 session
Use the left and right arrow keys to move along the chart.
Price data
Trading
- Previous close$7.89Nov 5
- Volume421.78KNov 6 session
Shares traded on all US exchanges in the last completed session. Live intraday volume covers IEX only, so it is left out.
- Avg. volume503.22KLast 21 sessions
The average daily shares traded over the last 21 trading sessions, about one calendar month.
- 52-week range: $7.73 to $11.80; now $7.97
The lowest and highest trades over the past 52 weeks, adjusted for splits. The marker shows the latest price.
Member SIPC.Low CommissionsLearn More (opens in a new tab)Sponsored. Affiliate link: I may earn a commission. The inclusion of Interactive Brokers’ (IBKR) name, logo or weblink is present pursuant to an advertising arrangement only. IBKR is not a contributor, reviewer, provider or sponsor of content published on this site, and is not responsible for the accuracy of any products or services discussed.
Performance
Past performance, measured to the Nov 6 close. Total return includes reinvested dividends.Price change only, without dividends. Compared with the S&P 500, using SPY.
PRTA beat the S&P 500 in 1 of 7 periods.
| Period | PRTA and S&P 500 | vs S&P 500 |
|---|---|---|
| Short term | ||
| 1M | PRTA: down 0.6% S&P 500: down 5.6% | PRTA beat the S&P 500 by 5.0 percentage points Beat |
| 3M | PRTA: down 7.1% S&P 500: down 4.1% | PRTA trailed the S&P 500 by 3.0 percentage points Trailed |
| YTD | PRTA: down 16.5% S&P 500: up 8.7% | PRTA trailed the S&P 500 by 25.2 percentage points Trailed |
| 1Y | PRTA: down 20.9% S&P 500: up 10.9% | PRTA trailed the S&P 500 by 31.8 percentage points Trailed |
| Long term | ||
| 3Y | PRTA: down 77.7% S&P 500: up 75.0% −39.4% vs +20.5% a year | PRTA trailed the S&P 500 by 152.7 percentage points Trailed |
| 5Y | PRTA: down 86.5% S&P 500: up 67.8% −33.0% vs +10.9% a year | PRTA trailed the S&P 500 by 154.3 percentage points Trailed |
| 10Y | PRTA: down 81.8% S&P 500: up 313.1% −15.7% vs +15.2% a year | PRTA trailed the S&P 500 by 394.9 percentage points Trailed |
$10,000 invested in PRTA 10 years ago (Nov 4, 2016) would be worth about $1,817 at the close on , with dividends reinvested. The same amount in the S&P 500 would be worth about $41,313.
PRTA beat the S&P 500 in 1 of 7 periods.
| Period | PRTA and S&P 500 | vs S&P 500 |
|---|---|---|
| Short term | ||
| 1M | PRTA: down 0.6% S&P 500: down 5.6% | PRTA beat the S&P 500 by 5.0 percentage points Beat |
| 3M | PRTA: down 7.1% S&P 500: down 4.3% | PRTA trailed the S&P 500 by 2.8 percentage points Trailed |
| YTD | PRTA: down 16.5% S&P 500: up 7.8% | PRTA trailed the S&P 500 by 24.3 percentage points Trailed |
| 1Y | PRTA: down 20.9% S&P 500: up 9.7% | PRTA trailed the S&P 500 by 30.6 percentage points Trailed |
| Long term | ||
| 3Y | PRTA: down 77.7% S&P 500: up 68.8% −39.4% vs +19.1% a year | PRTA trailed the S&P 500 by 146.5 percentage points Trailed |
| 5Y | PRTA: down 86.5% S&P 500: up 56.9% −33.0% vs +9.4% a year | PRTA trailed the S&P 500 by 143.4 percentage points Trailed |
| 10Y | PRTA: down 81.8% S&P 500: up 252.6% −15.7% vs +13.4% a year | PRTA trailed the S&P 500 by 334.4 percentage points Trailed |
$10,000 invested in PRTA 10 years ago (Nov 4, 2016) would be worth about $1,817 at the close on , not counting dividends. The same amount in the S&P 500 would be worth about $35,257.
All-time high
$78.89
Closing high on . Now 89.9% below that record.
Split-adjusted daily closes since Dec 21, 2012.
Stock splits
PRTA hasn’t split since its price history begins in 2012.
Valuation
The Nov 6 close compared with the last 12 months of reported results (the four quarters to Jun 30, 2026). Tap a metric to see how it’s calculated.
Price-to-earnings (P/E)
n/mDiluted EPS of −$0.84 over the last 12 months
A P/E ratio isn’t meaningful while earnings over the last 12 months are negative. When PRTA was profitable over the past five years, its P/E ranged from 15.7× to 38.5×, with a median of 24.7×. How to read P/E
Other valuation measures
- 7.7×Last 12 months’ revenue
Market value divided by revenue over the last 12 months. Useful when earnings are small or negative.
P/S = Market cap ÷ Revenue (last 12 months)Price-to-sales ratio - 1.5×Book value as of Jun 30, 2026
Price relative to accounting equity (book value) per share on the Jun 30, 2026 balance sheet. Asset-light companies often trade far above book value.
P/B = Price ÷ Book value per sharePrice-to-book ratio - −14.55%Last 12 months’ free cash flow
Free cash flow over the last 12 months as a share of the company’s market value: the cash the business generated for each dollar of stock.
FCF yield = Free cash flow (last 12 months) ÷ Market capFree cash flow - $136.05MAt the Nov 6 close
What it would cost to buy the whole business: the market cap at the Nov 6 close, plus debt, minus cash and short-term investments from the Jun 30, 2026 balance sheet.
EV = Market cap + Debt − Cash and short-term investmentsEV/EBITDA explained
Build your own PRTA DCF in Excel. Value Prothena with your own growth and margin assumptions.Browse DCF models Free DCF calculator
Financials
Reported results, not forecasts. From company filings via Tiingo; the latest report is Q2 FY26, the quarter ended Jun 30, 2026. “Last 12 months” means the four quarters from Jul 1, 2025 to Jun 30, 2026, and balance-sheet figures are as of Jun 30, 2026.
Revenue and net income
Last 12 months, with the change from the 12 months before
- Revenue
- $54.53Mup 427.3%
- Net income
- −$43.99M
- Diluted EPS
- −$0.84
Data table
| Period | Revenue | Net income | Diluted EPS |
|---|---|---|---|
| Q3 FY24 (Sep 30, 2024) | $970.00K | −$59.00M | −$1.10 |
| Q4 FY24 (Dec 31, 2024) | $2.12M | −$57.96M | −$1.07 |
| Q1 FY25 (Mar 31, 2025) | $2.83M | −$60.20M | −$1.12 |
| Q2 FY25 (Jun 30, 2025) | $4.42M | −$125.77M | −$2.34 |
| Q3 FY25 (Sep 30, 2025) | $2.42M | −$36.54M | −$0.68 |
| Q4 FY25 (Dec 31, 2025) | $21.00K | −$21.59M | −$0.40 |
| Q1 FY26 (Mar 31, 2026) | $51.08M | $32.72M | $0.60 |
| Q2 FY26 (Jun 30, 2026) | $1.01M | −$18.58M | −$0.36 |
| Period | Revenue | Net income | Diluted EPS |
|---|---|---|---|
| FY21 (Dec 31, 2021) | $200.58M | $66.98M | $1.38 |
| FY22 (Dec 31, 2022) | $53.91M | −$116.95M | −$2.47 |
| FY23 (Dec 31, 2023) | $91.37M | −$147.03M | −$2.76 |
| FY24 (Dec 31, 2024) | $135.16M | −$122.31M | −$2.27 |
| FY25 (Dec 31, 2025) | $9.68M | −$244.09M | −$4.53 |
Margins
- Gross 100.0%
- Operating −101.8%
- Net −80.7%
The percentages above the chart cover the last 12 months; the lines show each quarter. What margins tell you
Cash flow
- −$60.71MLast 12 months
Cash from operations minus capital spending: the cash left after the business maintains and grows its assets.
FCF = Operating cash flow − Capital spendingFree cash flow - Operating cash flow−$60.05MLast 12 months
- Capital spending$662.00KLast 12 months
- −111.3%Last 12 months
Free cash flow as a share of revenue, both over the last 12 months.
Shareholder returns
- $22.53MLast 12 months
Cash spent repurchasing shares, net of shares issued. Buybacks shrink the share count, so each remaining share owns more of the company.
- Dividends paid$0.00Last 12 months
- Total returned$22.53MLast 12 months
Balance sheet
- $289.05MAs of Jun 30, 2026
Cash plus short- and long-term marketable securities on the Jun 30, 2026 balance sheet.
- Total debt$6.99MAs of Jun 30, 2026
- Net cash$282.06MAs of Jun 30, 2026
- 25.05As of Jun 30, 2026
Current assets divided by current liabilities on the Jun 30, 2026 balance sheet. Above 1 means short-term assets cover the bills due within a year.
Current ratio = Current assets ÷ Current liabilitiesCurrent ratio - 0.02As of Jun 30, 2026
Total debt divided by shareholders’ equity on the Jun 30, 2026 balance sheet: a measure of financial leverage.
D/E = Total debt ÷ Shareholders’ equityDebt-to-equity ratio
Financial strength
- 5 of 9Last 12 months
vs the 12 beforeA 0–9 checklist from accounting professor Joseph Piotroski. Each test compares the last 12 months with the 12 months before and scores a point if it passes. 8–9 is strong; 0–2 is weak.
- ✗Net income was positive: not passed
- ✗Operating cash flow was positive: not passed
- ✓Return on assets improved: passed
- ✗Operating cash flow exceeded net income: not passed
- ✓Long-term debt fell relative to assets: passed
- ✓Current ratio improved: passed
- ✓Share count didn’t rise: passed
- ✗Gross margin improved: not passed
- ✓Asset turnover (revenue ÷ assets) improved: passed
- −15.0%Last 12 months
Over the last 12 months, Prothena lost money: its net loss was 15.0% of its shareholders’ equity (averaged over the last four quarter-ends). It describes the past year, not an expected return.
ROE = Net income (last 12 months) ÷ Average equityReturn on equity - −13.2%Last 12 months
Over the last 12 months, Prothena’s net loss was 13.2% of its total assets (averaged over the last four quarter-ends).
ROA = Net income (last 12 months) ÷ Average total assets
About Prothena Corporation plc
Prothena Corporation plc is a clinical-stage biotechnology company with expertise in protein dysregulation and a pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare peripheral amyloid diseases. Fueled by its deep scientific expertise built over decades of research, Prothena is advancing a pipeline of therapeutic candidates for a number of indications and novel targets for which its ability to integrate scientific insights around neurological dysfunction and the biology of misfolded proteins can be leveraged. Prothena’s pipeline includes both wholly owned and partnered programs being developed for the potential treatment of diseases including ATTR amyloidosis with cardiomyopathy, Alzheimer’s disease, Parkinson’s disease and a number of other neurodegenerative diseases.
- Sector
- Healthcare
- Industry
- Biotechnology
- Headquarters
- Ireland
- SEC filings
- EDGAR (opens in a new tab)
- Exchange
- Nasdaq
- Asset type
- Common stock
- Price history since
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PRTA stock FAQ
What is PRTA stock’s price today?
Prothena (PRTA) traded at $7.97 at the close on , up $0.08 (1.01%) from the previous close of $7.89. Over the past 52 weeks it has traded between $7.73 and $11.80.
If you invested $1,000 in PRTA 10 years ago, how much would you have now?
With dividends reinvested, $1,000 invested in PRTA on would be worth about $182 at the close on , a total return of −81.8%. The same $1,000 would be worth $135 if invested five years ago and $791 if invested one year ago. Past performance doesn’t predict future returns.
What is Prothena’s market cap?
Prothena’s market capitalization is about $417.3 million. That’s Tiingo’s daily market cap for , at that day’s closing price of $7.97 (how market cap works). Prothena reported 52.35M shares outstanding at the end of its latest quarter ().
What is PRTA’s P/E ratio?
PRTA’s P/E ratio isn’t meaningful right now because its earnings over the four quarters to are negative (diluted EPS of −$0.84). When it was profitable over the past five years, its P/E ranged from 15.7 to 38.5.
How much revenue does Prothena make?
Prothena reported $54.5 million of revenue over the four quarters to , up 427.3% from the twelve months before. In its latest quarter (Q2 FY26, ended ) revenue was $1.0 million, down 77.1% from a year earlier.
Is Prothena profitable?
Not over the four quarters to . Prothena reported a net loss of $44.0 million across those four quarters on $54.5 million of revenue.
What are PRTA’s earnings per share?
PRTA’s diluted earnings per share were −$0.84 over the four quarters to , compared with −$5.63 in the twelve months before. The latest quarter (Q2 FY26) brought −$0.36 per share, against −$2.34 a year earlier (how EPS works).
Does PRTA pay a dividend?
Prothena hasn’t paid a dividend in the last twelve months.
What is PRTA’s 52-week high and low?
Over the past 52 weeks PRTA has traded as low as $7.73 and as high as $11.80. At $7.97 at the close on , it is 32.5% below that high and 3.1% above the low.
What is PRTA’s all-time high?
PRTA’s highest closing price was $78.89 on , adjusted for stock splits. At $7.97 at the close on , it is 89.9% below that record.
Has PRTA stock ever split?
No. PRTA hasn’t split since its price history begins in 2012.
How has PRTA stock performed?
Including dividends and measured to the close on , PRTA has returned −16.5% so far this year and −20.9% over the past year, and −86.5% over five years (−33.0% a year). Over the same periods the S&P 500, measured by SPY, returned +8.7%, +10.9% and +67.8%. Past performance doesn’t predict future returns.
What sector and industry is Prothena in?
Prothena is in the Healthcare sector and the Biotechnology industry, and is headquartered in Ireland.
What exchange does PRTA trade on?
Prothena trades on the Nasdaq under the ticker symbol PRTA. Its price history on this dashboard begins on .
Member SIPC.Low CommissionsLearn More (opens in a new tab)Sponsored. Affiliate link: I may earn a commission. The inclusion of Interactive Brokers’ (IBKR) name, logo or weblink is present pursuant to an advertising arrangement only. IBKR is not a contributor, reviewer, provider or sponsor of content published on this site, and is not responsible for the accuracy of any products or services discussed.
About this data. Data sourced by Tiingo (opens in a new tab). The live price is Tiingo’s real-time price, based on IEX trades and quotes; intraday charts show IEX trades, and volume figures are consolidated totals for completed sessions. Prices are split-adjusted, and total returns assume dividends are reinvested. Financials come from company filings and can lag new reports. Times are Eastern.
This page is for education, not investment advice. Past performance doesn't predict future returns. Logos provided by Logo.dev (opens in a new tab).
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