Prothena Corp Public Ltd Co (PRTA) stock
PRTANasdaqPharmaceutical PreparationsFiscal year ends December 31
Financials through Q3 FY2026, quarter ended Sep 30, 2026Last filing: 10-Q on Nov 5, 2026Score 12/3018% below fair value
$8.23−0.50 (-5.73%)
Close on Nov 12, 2026Market cap $422.50MP/E –Yield –
Prothena Corp Public statistics
74 measures from SEC filings and the closing price. Hover a name for the formula; the last column is the median of companies in the same industry group.
Important dates
- Next earnings
- Feb 18, 2027 (estimated, after the close)
- Last ex-dividend date
- No dividends
- Fundamentals through
- Sep 30, 2026
- Share price as of
- Nov 12, 2026
Valuation ratiosIndustry
- P/TBV Ratio
- 1.57
- 2.29
Enterprise valuationIndustry
- EV / Sales
- 2.87
- 2.60
Share statisticsIndustry
- Shares Change (YoY)
- -1.75%
- 10.9%
- Shares Change (QoQ)
- -0.78%
- 0.51%
- Float
- 35M
- 49M
- Shares Held by Insiders
- 32.0%
- 12.1%
- Shares Held by Institutions
- 92.2%
- 56.4%
Short sellingIndustry
- Short Interest
- 8M
- –
- Short Interest Change
- -0.36%
- -0.76%
- Short % of Float
- 22.7%
- 9.04%
- Short % of Shares Outstanding
- 15.4%
- 6.30%
- Days to Cover
- 15.69
- 5.13
Stock price statisticsIndustry
- 52-Week High
- $11.80
- –
- 52-Week Low
- $7.73
- –
- 20-Day Moving Average
- $8.43
- –
- 50-Day Moving Average
- $8.57
- –
- 200-Day Moving Average
- $9.18
- –
- Average True Range (14)
- $0.45
- –
- Price Change (1 Week)
- 4.31%
- 1.51%
- Price Change (1 Month)
- -1.67%
- -2.35%
- Price Change (3 Months)
- -7.11%
- -21.1%
- Price Change (6 Months)
- -16.5%
- -22.6%
- Price Change (YTD)
- -13.8%
- -22.6%
- Price Change (1 Year)
- -21.5%
- -20.7%
- Price Change (3 Years)
- -75.2%
- -27.4%
- Price Change (5 Years)
- -85.6%
- -77.3%
- Price Change (10 Years)
- -87.1%
- -62.7%
- Average Volume (10 Days)
- 419,838
- –
- Average Volume (20 Days)
- 467,957
- –
- Average Volume (90 Days)
- 487,000
- –
- Relative Volume
- 0.48
- 0.79
- Relative Strength Index (14)
- 46.7
- 44.7
- Volatility (1 Year)
- 49.2%
- 80.4%
- Beta (5 Years)
- 0.86
- 1.07
MarginsIndustry
- Pretax Margin
- -45.4%
- -11.8%
- EBITDA Margin
- -63.1%
- -27.7%
Returns on capitalIndustry
- Return on Equity (ROE)
- -8.50%
- -51.2%
- Return on Assets (ROA)
- -7.53%
- -40.6%
- Return on Capital Employed (ROCE)
- -12.5%
- -38.0%
Financial positionIndustry
- Current Ratio
- 23.95
- 3.30
- Quick Ratio
- 23.73
- 2.42
GrowthIndustry
- Revenue Growth (YoY)
- 347.4%
- 7.01%
- Revenue Growth (3Y CAGR)
- -43.6%
- 2.25%
- Revenue Growth (5Y CAGR)
- 62.6%
- 6.41%
EfficiencyIndustry
- Asset Turnover
- 0.17
- 0.40
- Revenue Per Employee
- $787.09K
- $429.29K
- Profits Per Employee
- -$357.61K
- -$683.67K
- Employee Count
- 67
- 75
- WACC
- 9.28%
- 10.1%
Income statement (TTM)Industry
- Pretax Income
- -$23.95M
- -$13.23M
Balance sheetIndustry
- Net Cash (Debt)
- $271.37M
- $17.46M
- Net Cash Per Share
- $5.29
- $0.72
- Equity (Book Value)
- $268.84M
- $53.27M
- Book Value Per Share
- $5.24
- $1.50
- Tangible Book Value
- $268.84M
- $26.82M
- Working Capital
- $262.43M
- $79.47M
Cash flow (TTM)Industry
Dividends and yieldsIndustry
- Earnings Yield
- -5.67%
- -20.8%
Taxes and interestIndustry
- Income Tax
- $15.00K
- $74.00K
Scores and fair valueIndustry
- Altman Z-Score
- 11.50
- 0.30
- Piotroski F-Score
- 2
- 4
Total return vs. the S&P 500
Price change plus reinvested dividends, to the close on Nov 12, 2026. The S&P 500 is measured by the SPY fund.
| Period | PRTA | S&P 500 | Difference | PRTA per year | S&P 500 per year |
|---|---|---|---|---|---|
| 1 month | -2.4% | -2.7% | +0.3 pts | ||
| 3 months | -11.1% | -1.7% | −9.4 pts | ||
| Year to date | -13.8% | +11.9% | −25.7 pts | ||
| 1 year | -24.1% | +12.0% | −36.1 pts | ||
| 3 years | -75.3% | +78.2% | −153.5 pts | -37.3% | +21.2% |
| 5 years | -85.6% | +73.2% | −158.8 pts | -32.1% | +11.6% |
| 10 years | -87.1% | +309.6% | −396.7 pts | -18.5% | +15.1% |
Short interest
Shares sold short and not yet covered, reported by brokers to FINRA twice a month. Latest settlement date Oct 30, 2026.
8M PRTA shares were sold short on Oct 30, 2026, down 0.4% from the previous report, or 22.67% of the shares available to trade. At recent volumes it would take 15.7 days to buy them back. Over the last 20 sessions, 63.9% of the volume reported to FINRA was short selling.
| Settlement date | Shares short | Change | Avg. daily volume | Days to cover |
|---|---|---|---|---|
| Oct 30, 2026 | 7,911,160 | -0.4% | 504,196 | 15.7 |
| Oct 15, 2026 | 7,939,666 | -0.9% | 597,798 | 13.3 |
| Sep 30, 2026 | 8,010,864 | -6.2% | 580,885 | 13.8 |
| Sep 15, 2026 | 8,544,664 | +0.6% | 322,027 | 26.5 |
| Aug 31, 2026 | 8,495,796 | -0.6% | 341,894 | 24.9 |
| Aug 14, 2026 | 8,545,127 | +4.6% | 436,939 | 19.6 |
| Jul 31, 2026 | 8,172,438 | -0.3% | 585,253 | 14.0 |
| Jul 15, 2026 | 8,196,964 | -2.1% | 499,741 | 16.4 |
| Jun 30, 2026 | 8,369,568 | +6.4% | 759,430 | 11.0 |
| Jun 15, 2026 | 7,866,857 | +1.7% | 492,334 | 16.0 |
| May 29, 2026 | 7,737,902 | +9.0% | 558,736 | 13.8 |
| May 15, 2026 | 7,097,854 | +3.3% | 547,700 | 13.0 |
Ratios use trailing-twelve-month results and the latest balance sheet. How we calculate.
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