Latest Ratios: P/E Ratio -2.1x · EV/EBITDA N/A · ROE -63.6%. (2010–2025 historical series)
Price-based multiples — how expensive the stock is relative to earnings, sales, book value, and cash flow
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Market Cap | $507M | $514M | $745M | $1.9B | $2.9B | $2.4B | $479M | $631M | $407M | $1.4B | $1.7B |
| Enterprise Value | $213M | $220M | $284M | $1.3B | $2.2B | $1.8B | $202M | $279M | $31M | $1.0B | $1.4B |
| P/E Ratio → | -2.14 | — | — | — | — | 35.80 | — | — | — | — | — |
| P/S Ratio | 52.33 | 53.08 | 5.51 | 21.17 | 52.94 | 11.94 | 561.99 | 775.59 | 426.66 | 51.30 | 1601.64 |
| P/B Ratio | 1.86 | 1.83 | 1.53 | 3.44 | 4.59 | 5.14 | 2.61 | 2.31 | 1.26 | 3.47 | 4.62 |
| P/FCF | — | — | — | — | — | 26.01 | — | — | — | — | — |
| P/OCF | — | — | — | — | — | 25.85 | — | — | — | — | — |
P/E links to full P/E history page with 30-year chart
Enterprise-value multiples — capital-structure-neutral measures of total business value
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| EV / Revenue | — | 22.76 | 2.10 | 14.52 | 39.89 | 9.11 | 236.62 | 342.20 | 32.82 | 38.02 | 1283.53 |
| EV / EBITDA | — | — | — | — | — | 25.00 | — | — | — | — | — |
| EV / EBIT | — | — | — | — | — | 25.39 | — | — | — | — | — |
| EV / FCF | — | — | — | — | — | 19.86 | — | — | — | — | — |
Margins and return-on-capital ratios measuring operating efficiency
Full margin charts and quarterly trend are on the Earnings History page
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Gross Margin | 61.8% | 61.8% | 100.0% | 100.0% | 100.0% | 100.0% | -8678.9% | -6145.2% | -10495.1% | -388.9% | -11230.2% |
| Operating Margin | -1905.8% | -1905.8% | -114.4% | -209.1% | -244.1% | 35.9% | -13216.2% | -10527.9% | -16634.0% | -564.2% | -15121.8% |
| Net Profit Margin | -2520.6% | -2520.6% | -90.5% | -160.9% | -217.0% | 33.4% | -13029.8% | -9542.6% | -16297.9% | -556.8% | -15176.1% |
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| ROE | -63.6% | -63.6% | -23.3% | -24.8% | -21.5% | 20.6% | -48.6% | -26.1% | -42.6% | -39.7% | -44.1% |
| ROA | -55.9% | -55.9% | -19.7% | -20.2% | -17.1% | 14.2% | -29.5% | -16.9% | -31.3% | -32.0% | -37.9% |
| ROIC | -2099.8% | -2099.8% | -439.4% | — | — | — | — | — | — | -325.2% | -1203.6% |
| ROCE | -47.0% | -47.0% | -27.2% | -28.4% | -20.5% | 16.3% | -31.8% | -19.4% | -33.7% | -35.4% | -40.8% |
Solvency and debt-coverage ratios — lower is generally safer
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Debt / Equity | 0.05 | 0.05 | 0.02 | 0.02 | 0.01 | 0.03 | 0.10 | 0.08 | 0.16 | 0.13 | 0.14 |
| Debt / EBITDA | — | — | — | — | — | 0.17 | — | — | — | — | — |
| Net Debt / Equity | — | -1.05 | -0.95 | -1.08 | -1.13 | -1.22 | -1.51 | -1.29 | -1.16 | -0.90 | -0.92 |
| Net Debt / EBITDA | — | — | — | — | — | -7.75 | — | — | — | — | — |
| Debt / FCF | — | — | — | — | — | -6.16 | — | — | — | — | — |
| Interest Coverage | — | — | — | — | — | — | — | — | -41.23 | -41.73 | -184.20 |
Net cash position: cash ($308M) exceeds total debt ($14M)
Short-term solvency ratios and asset-utilisation metrics
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Current Ratio | 7.72 | 7.72 | 10.01 | 11.24 | 14.34 | 17.48 | 11.58 | 21.36 | 28.90 | 11.41 | 9.53 |
| Quick Ratio | 7.72 | 7.72 | 10.01 | 11.24 | 14.34 | 17.48 | 11.58 | 21.36 | 28.90 | 11.41 | 9.53 |
| Cash Ratio | 7.53 | 7.53 | 9.72 | 10.88 | 14.17 | 17.31 | 11.43 | 21.21 | 28.65 | 11.17 | 9.42 |
| Asset Turnover | — | 0.03 | 0.25 | 0.13 | 0.07 | 0.33 | 0.00 | 0.00 | 0.00 | 0.06 | 0.00 |
| Inventory Turnover | — | — | — | — | — | — | — | — | — | — | — |
| Days Sales Outstanding | — | — | — | 20.61 | 0.42 | 0.02 | 6.42 | 30.49 | 0.76 | 3.18 | 61.58 |
Earnings, FCF, buyback, and dividend yields — total returns to shareholders
Full dividend history and growth charts are on the Dividend History page
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Dividend Yield | — | — | — | — | — | — | — | — | — | — | — |
| Payout Ratio | — | — | — | — | — | — | — | — | — | — | — |
| Metric | TTM | FY 2025 | FY 2024 | FY 2023 | FY 2022 | FY 2021 | FY 2020 | FY 2019 | FY 2018 | FY 2017 | FY 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Earnings Yield | — | — | — | — | — | 2.8% | — | — | — | — | — |
| FCF Yield | — | — | — | — | — | 3.8% | — | — | — | — | — |
| Buyback Yield | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% |
| Total Shareholder Yield | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% |
| Shares Outstanding | — | $54M | $54M | $53M | $47M | $48M | $40M | $40M | $40M | $38M | $34M |
Clinical milestone dependency
As reported in recent financial statements, Prothena's forward P/E of 214.56 suggests that current market pricing is predicated on highly optimistic long-term commercialization outcomes rather than existing fundamental performance, which remains characterized by significant volatility and a lack of consistent, recurring revenue streams from its pipeline.
The extreme valuation multiples reflect a market pricing model that heavily discounts the probability of success for late-stage assets while ignoring the current lack of commercial scale. Investors should monitor whether these multiples compress as clinical trial timelines for birtamimab extend, as the current premium appears to be built on speculative future cash flows rather than tangible earnings growth.
Based on reported figures, Prothena's ROIC has fluctuated wildly, including a negative 174.6% in 2025Q1, which highlights the company's inability to generate positive returns on invested capital while it remains in a capital-intensive, pre-commercial phase of its drug development lifecycle.
The erratic nature of these returns is a direct consequence of the lumpy milestone-based revenue model, which fails to provide a stable denominator for capital efficiency metrics. This volatility suggests that traditional return-on-capital analysis is currently less meaningful than tracking the company's ability to extend its cash runway through strategic partnerships.
According to the provided financial data, Prothena's asset turnover remains negligible at 0.15 in 2026Q1, reflecting a business model that has yet to deploy a commercial product and therefore lacks the operational throughput typically required to drive meaningful asset utilization or working capital efficiency.
The lack of meaningful turnover ratios underscores the company's status as a research-focused entity rather than an operational one. Investors should be cautious in interpreting these metrics, as they are currently driven by the timing of collaboration payments rather than the underlying efficiency of the company's core research and development processes.
As indicated by the company's reported figures, the current ratio of 10.43 in 2026Q1 appears robust on the surface, yet this liquidity is highly sensitive to the timing of milestone-based inflows and the ongoing, significant cash burn required to sustain late-stage clinical trial operations.
While the high current ratio suggests a comfortable short-term buffer, it does not account for the structural necessity of future capital raises or additional partnership milestones to fund long-term operations. The liquidity position should be viewed as a finite runway that is being steadily consumed by the high fixed costs of the current clinical pipeline.
Analysis of the financial statements suggests that the P/E ratio is the most commonly misapplied metric for Prothena, as it obscures the reality that the company's earnings are driven by non-recurring milestone events rather than sustainable, organic commercial growth or predictable operational margins.
Investors should instead focus on cash burn rates and the remaining performance obligations, as these provide a more accurate picture of the company's financial health than earnings-based multiples. Relying on P/E ratios in this context may lead to a fundamental misunderstanding of the company's risk profile and its reliance on external, non-dilutive funding sources.
Includes 30+ ratios · 16 years · Updated daily
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Quick answers to the most common questions about buying PRTA stock.
Prothena Corporation plc's current P/E ratio is -2.1x. The historical average is 35.8x.
Prothena Corporation plc's return on equity (ROE) is -63.6%. The historical average is -31.3%.
Based on historical data, Prothena Corporation plc is trading at a P/E of -2.1x. Compare with industry peers and growth rates for a complete picture.
Prothena Corporation plc has 61.8% gross margin and -1905.8% operating margin.