Trending NewsTrending NewsNASDAQ:PRTA Prothena (PRTA) Stock Price, News & Analysis $4.70 +0.10 (+2.17%) Closing price 04:00 PM EasternExtended Trading$4.59 -0.11 (-2.32%) As of 04:22 PM Eastern Extended trading is trading that happens on electronic markets outside of regular trading hours. This is a fair market value extended hours price provided by Polygon.io. Learn more. Add Compare Share Share Stock Analysis Stock AnalysisAnalyst ForecastsChartCompetitorsEarningsFinancialsHeadlinesInsider TradesOptions ChainOwnershipSEC FilingsShort InterestTrendsBuy This Stock About Prothena Stock (NASDAQ:PRTA) 30 days 90 days 365 days Advanced Chart View Price History Chart DataSkip Price History Chart Get Prothena alerts:Sign Up Key Stats Today's Range$4.63▼$4.9450-Day Range$4.58▼$13.3752-Week Range$4.32▼$25.42Volume5.38 million shsAverage Volume680,522 shsMarket Capitalization$252.99 millionP/E RatioN/ADividend YieldN/APrice Target$31.50Consensus RatingHold Company OverviewProthena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation in the United States. The company is involved in developing birtamimab, an investigational humanized antibody that is in Phase III clinical trial for the treatment of AL amyloidosis; Prasinezumab, a humanized monoclonal antibody, for the treatment of Parkinson's disease and other related synucleinopathies which is in Phase IIb clinical trial; NNC6019 that is in Phase lI clinical trial for the treatment of ATTR amyloidosis; and BMS-986446 and PRX012, which is in Phase I clinical trial for the treatment of Alzheimer's disease. Its discovery and preclinical programs include PRX123, a dual Aß-Tau vaccine for the treatment and prevention of Alzheimer's disease; and PRX019 for the treatment of neurogenerative diseases, as well as TDP-43 for the treatment of amyotrophic lateral sclerosis. Prothena Corporation plc has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target a-synuclein, including prasinezumab; and a collaboration agreement with Bristol-Myers Squibb to develop and commercialize antibodies targeting tau, TDP-43. The company was incorporated in 2012 and is based in Dublin, Ireland.Read More… Prothena Stock Analysis - MarketRank™See Top-Rated MarketRank™ Stocks55th Percentile Overall ScorePRTA MarketRank™: Prothena scored higher than 55% of companies evaluated by MarketBeat, and ranked 491st out of 933 stocks in the medical sector. Scores are calculated by averaging available category scores, with extra weight given to analysis and valuation. Analyst's Opinion4.2 / 5Analyst RatingHold Consensus RatingProthena has received a consensus rating of Hold. The company's average rating score is 2.33, and is based on 4 buy ratings, 4 hold ratings, and 1 sell rating.Amount of Analyst CoverageProthena has been the subject of 8 research reports in the past 90 days, demonstrating strong analyst interest in this stock.Read more about Prothena's stock forecast and price target. Earnings and Valuation1.3 / 5Proj. Earnings GrowthGrowing Earnings GrowthEarnings for Prothena are expected to grow in the coming year, from ($4.04) to ($3.33) per share.Price to Earnings Ratio vs. the MarketThe P/E ratio of Prothena is -2.05, which means that its earnings are negative and its P/E ratio cannot be compared to companies with positive earnings.Price to Earnings Ratio vs. SectorThe P/E ratio of Prothena is -2.05, which means that its earnings are negative and its P/E ratio cannot be compared to companies with positive earnings.Price to Book Value per Share RatioProthena has a P/B Ratio of 0.45. P/B Ratios below 1 indicate that a company could be undervalued with respect to its assets and liabilities.Read more about Prothena's valuation and earnings. Short Interest1.0 / 5Short Interest LevelBearish Percentage of Shares Shorted21.15% of the float of Prothena has been sold short.Short Interest Ratio / Days to CoverProthena has a short interest ratio ("days to cover") of 8.4.Change versus previous monthShort interest in Prothena has recently increased by 20.13%, indicating that investor sentiment is decreasing significantly. Dividend0.0 / 5Dividend StrengthN/A Dividend YieldProthena does not currently pay a dividend.Dividend GrowthProthena does not have a long track record of dividend growth. Sustainability and ESGN/AEnvironmental ScoreN/A Percentage of Shares Shorted21.15% of the float of Prothena has been sold short.Short Interest Ratio / Days to CoverProthena has a short interest ratio ("days to cover") of 8.4.Change versus previous monthShort interest in Prothena has recently increased by 20.13%, indicating that investor sentiment is decreasing significantly. News and Social Media2.1 / 5News Sentiment-0.31 News SentimentProthena has a news sentiment score of -0.31. This score is calculated as an average of sentiment of articles about the company over the last seven days and ranges from 2 (good news) to -2 (bad news). This is a lower news sentiment than the 0.87 average news sentiment score of Medical companies.News Coverage This WeekMarketBeat has tracked 40 news articles for Prothena this week, compared to 4 articles on an average week.Search Interest10 people have searched for PRTA on MarketBeat in the last 30 days. This is an increase of 150% compared to the previous 30 days.MarketBeat Follows3 people have added Prothena to their MarketBeat watchlist in the last 30 days. This is an increase of 200% compared to the previous 30 days. Company Ownership1.7 / 5Insider TradingN/A Insider Buying vs. Insider SellingIn the past three months, Prothena insiders have not sold or bought any company stock.Percentage Held by InsidersOnly 9.20% of the stock of Prothena is held by insiders.Percentage Held by Institutions97.08% of the stock of Prothena is held by institutions. High institutional ownership can be a signal of strong market trust in this company.Read more about Prothena's insider trading history. Receive PRTA Stock News and Ratings via Email Sign-up to receive the latest news and ratings for Prothena and its competitors with MarketBeat's FREE daily newsletter. Email Address PRTA Stock News HeadlinesWilliam P. Scully Acquires 2,000 Shares of Prothena Co. plc (NASDAQ:PRTA) StockMay 3, 2025 | insidertrades.comB of A Securities Downgrades Prothena (PRTA)May 29 at 9:48 AM | msn.comMarket Panic: Trump Just Dropped a Bomb on Your Stockstock Market Panic: Trump Just Dropped a Bomb on Your Stocks The market is in freefall—and Trump's new tariffs just lit the fuse. Millions of investors are blindsided as stocks plunge… but this is only Phase 1. If you're still holding the wrong assets, you could lose 30% or more in the coming weeks.May 29, 2025 | American Alternative (Ad)Prothena (NASDAQ:PRTA) Price Target Cut to $81.00 by Analysts at Piper SandlerMay 29 at 2:38 AM | americanbankingnews.comProthena (NASDAQ:PRTA) Stock Rating Lowered by OppenheimerMay 29 at 2:03 AM | americanbankingnews.comChardan Capital Issues Pessimistic Forecast for Prothena (NASDAQ:PRTA) Stock PriceMay 29 at 1:15 AM | americanbankingnews.comJefferies Downgrades Prothena Corporation (PRTA) After Negative Trial ResultsMay 29 at 12:57 AM | finance.yahoo.comOppenheimer Downgrades Prothena Corporation (NASDAQ:PRTA) to Perform from OutperformMay 28 at 2:24 PM | insidermonkey.comSee More Headlines PRTA Stock Analysis - Frequently Asked Questions How have PRTA shares performed this year? Prothena's stock was trading at $13.85 at the beginning of 2025. Since then, PRTA stock has decreased by 65.7% and is now trading at $4.7450. View the best growth stocks for 2025 here. How were Prothena's earnings last quarter? Prothena Co. plc (NASDAQ:PRTA) released its quarterly earnings results on Thursday, May, 8th. The biotechnology company reported ($1.12) earnings per share (EPS) for the quarter, missing the consensus estimate of ($0.92) by $0.20. Prothena's revenue was up 5500.0% compared to the same quarter last year. Who are Prothena's major shareholders? Top institutional investors of Prothena include Wellington Management Group LLP (9.66%), Price T Rowe Associates Inc. MD (6.42%), Armistice Capital LLC (4.08%) and Palo Alto Investors LP (3.08%). Insiders that own company stock include William P Scully, Gene G Kinney, Tran Nguyen, Dennis J Selkoe, Richard T Collier, Lars Ekman, Wagner M Zago, Michael J Malecek, Karin L Walker, Hideki Garren, Carol D Karp and Brandon S Smith. View institutional ownership trends. How do I buy shares of Prothena? Shares of PRTA stock can be purchased through any online brokerage account. Popular online brokerages with access to the U.S. stock market include Charles Schwab, E*TRADE, Fidelity, and Vanguard Brokerage Services. What other stocks do shareholders of Prothena own? Based on aggregate information from My MarketBeat watchlists, some other companies that Prothena investors own include Voyager Therapeutics (VYGR), American Water Works (AWK), Humana (HUM), Waste Connections (WCN), The RMR Group (RMR), DiamondRock Hospitality (DRH) and AUO (AUOTY). Company Calendar Last Earnings5/08/2025Today5/29/2025Next Earnings (Estimated)8/14/2025Fiscal Year End12/31/2025Get Stock AlertsIndustry, Sector and Symbol Stock ExchangeNASDAQ SectorMedical Industry Pharmaceutical preparations Sub-IndustryPharmaceutical Products Current SymbolNASDAQ:PRTA CIK1559053 Webwww.prothena.com Phone(531) 236-2500Fax353-1902-3510Employees130Year FoundedN/APrice Target and Rating Average Stock Price Target$31.50 High Stock Price Target$81.00 Low Stock Price Target$6.00 Potential Upside/Downside+563.9%Consensus RatingHold Rating Score (0-4)2.33 Research Coverage9 Analysts Profitability EPS (Most Recent Fiscal Year)($2.08) Trailing P/E RatioN/A Forward P/E RatioN/A P/E GrowthN/ANet Income-$147.03 million Net Margins-90.50% Pretax Margin-105.02% Return on Equity-22.67% Return on Assets-19.68% Debt Debt-to-Equity RatioN/A Current Ratio11.52 Quick Ratio11.52 Sales & Book Value Annual Sales$137.94 million Price / Sales1.85 Cash FlowN/A Price / Cash FlowN/A Book Value$10.46 per share Price / Book0.45Miscellaneous Outstanding Shares53,827,000Free Float38,635,000Market Cap$255.41 million OptionableOptionable Beta0.11 13 Stocks Institutional Investors Won't Stop BuyingWhich stocks are hedge funds and endowments buying in today's market? Enter your email address and we'll send you MarketBeat's list of thirteen stocks that institutional investors are buying now.Get This Free Report This page (NASDAQ:PRTA) was last updated on 5/29/2025 by MarketBeat.com Staff From Our PartnersMarket Panic: Trump Just Dropped a Bomb on Your Stockstock Market Panic: Trump Just Dropped a Bomb on Your Stocks The market is in freefall—and Trump's new tarif...American Alternative | SponsoredJuly 2025 Rule Change to Impact Retirement InvestorsThere's a massive change from a new rule going into effect this July. And it's one the Big Banks are alread...Premier Gold Co | SponsoredWhite House to reset Social Security?Elon Musk's parting DOGE gift looks set to shock America... A single announcement by July 22nd could soon b...Altimetry | SponsoredIs President Trump Lying To You With This?President Trump’s economic transition isn’t without hardship. 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