PRTA
Prothena Corporation plc Healthcare - Biotechnology Investor Relations →
Prothena Corporation plc (PRTA) closed at $8.93 as of 2026-06-19, trading 68.4% below its 200-week moving average of $28.26. This places PRTA in the extreme value zone. The stock moved further from the line this week, up from -70.9% last week. The 14-week RSI sits at 48, indicating neutral momentum.
Trading volume is running at 1.7x of its 14-week average, which is in the normal range. The balance between buying and selling volume (1.03 ratio) is neutral — neither side is clearly dominating.
Over the past 656 weeks of data, PRTA has crossed below its 200-week moving average 7 times. On average, these episodes lasted 44 weeks. Historically, investors who bought PRTA at the start of these episodes saw an average one-year return of +91.3%.
With a market cap of $468 million, PRTA is a small-cap stock. Free cash flow yield is currently negative, meaning the company is burning cash. Return on equity stands at -40.3%. The stock trades at 1.5x book value.
Share count has increased 3.3% over three years, indicating dilution.
Over the past 12.7 years, a hypothetical investment of $100 in PRTA would have grown to $32, compared to $512 for the S&P 500. PRTA has returned -8.7% annualized vs 13.8% for the index, underperforming the broader market over this period.
In the past 12 months, corporate insiders have made 5 open-market purchases totaling $3,097,110. Multiple insiders purchased within a 30-day window — a cluster buy pattern that historically signals management confidence in the company's prospects. Notably, these purchases occurred while PRTA is trading below its 200-week moving average — insiders are buying when the market is most pessimistic.
Free cash flow has been declining. A deteriorating cash flow trend warrants extra scrutiny — the stock may be cheap for a reason.
Business Health
Annual financials — how the underlying business has performed over the past several years.
Cash Flow Free cash flow & net income ($M)
Revenue Annual revenue ($M) — business growth proxy
Total Debt Balance sheet debt ($M)
ROIC Return on invested capital (%)
FCF Yield Free cash flow / market cap (%) — Yartseva signal
Gross Margin Pricing power & competitive moat (%)
Shares Outstanding Buybacks vs dilution (millions)
Growth of $100: PRTA vs S&P 500
Monthly data normalized to $100 at start. Vertical dashed lines mark 200-week MA touches.
What Happens After PRTA Crosses Below the Line?
Across 7 historical episodes, buying PRTA when it crossed below its 200-week moving average produced an average return of +74.1% after 12 months (median +58.0%), compared to +12.9% for the S&P 500 over the same periods. 57% of those episodes were profitable after one year. After 24 months, the average return was +49.9% vs +26.4% for the index.
Each line shows $100 invested at the moment PRTA crossed below its 200-week MA. Bold blue = stock average. Gray dashed = S&P 500 average over same periods.
Bean Score Experimental
The Bean Score measures how far a stock's free cash flow yield has deviated from its own quarterly baseline, normalized by the stock's historical behavior. PRTA currently has negative free cash flow, so price-based dislocation levels are not available. The score still tracks yield deviation from baseline.
Quarterly FCF & Yield Trailing twelve-month free cash flow and yield at each quarter end
Signal Accuracy Collecting Data
The Bean Score system is accumulating weekly data to validate signal accuracy. After 13+ weeks of history, this section will display win rates and average returns for each σ threshold crossing — answering the question: "When this score says cheap or expensive, does the price subsequently move in the expected direction?"
Theoretical framework — not backtested or forward-tested. The Bean Score uses trailing twelve-month free cash flow yield as a dislocation identifier. It measures whether the market has pushed a stock's yield unusually far from its own baseline behavior. These levels are reference points for identifying potential swing trade opportunities, not buy/sell signals. FCF values update quarterly with earnings; between reports, all movement is price-driven.
Dislocation Scores Experimental
Each score measures deviation from PRTA's own historical baseline — the same idea as the Bean Score, applied to different fundamentals. Positive means cheaper or more dislocated than this stock's norm. Scores marked σ are normalized by the stock's own variability; pp values are simple deltas from its recent baseline.
Theoretical framework — not backtested. These scores describe how unusual today's readings are for this specific company. They are starting points for research, not buy or sell signals. Annual-statement scores (buyback, accruals, FCF vs history) rest on only ~4 yearly data points and are deltas, not sigmas.
Historical Touches
PRTA has crossed below its 200-week MA 7 times with an average 1-year return of +91.3% after recovery.
| Crossed Below | Recovered | Weeks | Max Depth | 1-Year Return | Return Since Touch |
|---|---|---|---|---|---|
| Jul 2014 | Aug 2014 | 3 | 8.7% | +223.9% | -51.6% |
| Oct 2014 | Oct 2014 | 1 | 4.8% | +143.1% | -51.4% |
| Dec 2014 | Dec 2014 | 1 | 6.8% | +267.1% | -50.8% |
| Dec 2017 | Feb 2021 | 166 | 81.5% | -72.3% | -78.2% |
| Mar 2021 | Mar 2021 | 1 | 0.5% | +43.2% | -58.2% |
| Oct 2023 | Dec 2023 | 7 | 10.4% | -57.2% | -75.0% |
| Dec 2023 | Ongoing | 130+ | 87.8% | Ongoing | -75.4% |
| Average | 44 | — | +91.3% | — |
Frequently Asked Questions
Is PRTA below its 200-week moving average?
Yes. As of 2026-06-19, Prothena Corporation plc (PRTA) is trading 68.4% below its 200-week moving average of $28.26. The current price is $8.93.
What is PRTA's 200-week moving average price?
Prothena Corporation plc's 200-week moving average is $28.26 as of 2026-06-19. This is the average weekly closing price over roughly the last 4 years, and it acts as a long-term trend line. When a stock drops below this level, it can signal that the price has fallen far enough from the long-term trend to attract value-oriented investors.
What happens when PRTA drops below its 200-week moving average?
PRTA has crossed below its 200-week moving average 7 times in our data. On average, buying at that moment produced a one-year return of +91.3%. These dips have historically been decent entry points. These episodes lasted 44 weeks on average.
Is PRTA a good value right now?
Here's what our data says about PRTA as of 2026-06-19: The stock is below its 200-week moving average, which is the starting point for our analysis. The 14-week RSI is 48. Free cash flow is currently negative. Return on equity is -40.3%. Price-to-book is 1.5x. This is not a buy or sell recommendation — always do your own research.
How does PRTA compare to the S&P 500?
Over the past 12.7 years, $100 invested in PRTA would have grown to $32, compared to $512 for the S&P 500. That's -8.7% annualized vs 13.8% for the index. PRTA has underperformed the broader market over this period.
Not financial advice. This is an educational tool. Past performance does not guarantee future results. Do your own research before making investment decisions.
Data as of week of 2026-06-19