NASDAQ:PRTA Prothena (PRTA) Stock Price, News & Analysis $9.07 -0.23 (-2.42%) As of 01:59 PM Eastern This is a fair market value price provided by Massive. Learn more. Add Compare Share Share Stock Analysis Stock AnalysisAnalyst ForecastsChartCompetitorsEarningsFDA EventsFinancialsInsider TradesNews and TrendsOptions ChainOwnershipSEC FilingsShort Interest About Prothena Stock (NASDAQ:PRTA) View Price History Chart DataSkip Price History Chart 1 Day 5 Days 30 Days 90 Days 1 Year Advanced 1 Day 1 Day 5 Days 30 Days 90 Days 1 Year Advanced Show volume Show extended hours Get Prothena alerts:Sign Up Key Stats Today's Range$9.06▼$9.2650-Day Range$8.12▼$9.8552-Week Range$7.73▼$11.80Volume117,707 shsAverage Volume502,979 shsMarket Capitalization$475.08 millionP/E RatioN/ADividend YieldN/APrice Target$24.57Consensus RatingModerate Buy Company Overview Prothena Corporation plc is a clinical-stage biotechnology company dedicated to the discovery and development of novel therapies for neurodegenerative and rare diseases driven by misfolded proteins. The company’s research focuses on immunotherapies and small molecules designed to target and clear disease-causing protein aggregates. Prothena leverages proprietary protein engineering and antibody discovery platforms to advance candidates through preclinical and clinical stages. The company’s most advanced program is an antibody targeting aggregated alpha-synuclein for the potential treatment of Parkinson’s disease, currently in mid-stage clinical trials. Additional pipeline candidates include therapies for amyloid light chain (AL) amyloidosis and other protein misfolding disorders. Prothena collaborates with global pharmaceutical partners to further develop and commercialize its product candidates, pooling resources and expertise to accelerate research timelines. Founded in 2012 as a spin-out from Elan Corporation, Prothena is headquartered in South San Francisco, California, with research operations in both the United States and Ireland. The company maintains a global focus, engaging regulators and trial sites across North America, Europe and Asia to support its clinical development programs. Prothena’s commitment to addressing high-unmet-need diseases is reflected in its strategic partnerships and research investments. Prothena is led by President and Chief Executive Officer Gene Kinney, whose experience spans decades in the pharmaceutical and biotechnology sectors. Under his leadership, the company has built a multidisciplinary team of scientists, clinicians and commercial experts. Prothena’s board and management team bring deep expertise in protein science, immunology and drug development to guide the company’s mission of bringing new treatment options to patients worldwide. AI Generated. May Contain Errors. Read More Prothena Stock Analysis - MarketRank™See Top-Rated MarketRank™ Stocks64th Percentile Overall ScorePRTA MarketRank™: Prothena scored higher than 64% of companies evaluated by MarketBeat, and ranked 283rd out of 907 stocks in the healthcare sector. Scores are calculated by averaging available category scores, with extra weight given to analysis and valuation. Analyst's Opinion4.0 / 5Analyst RatingModerate Buy Consensus RatingProthena has received a consensus rating of Moderate Buy. The company's average rating score is 2.75, and is based on 1 strong buy rating, 5 buy ratings, 1 hold rating, and 1 sell rating.Upside PotentialProthena has a consensus price target of $24.57, representing about 167.4% upside from its current price of $9.19.Amount of Analyst CoverageProthena has only been the subject of 3 research reports in the past 90 days.Read more about Prothena's stock forecast and price target. Earnings and Valuation0.0 / 5Proj. Earnings GrowthDecreasing Earnings GrowthEarnings for Prothena are expected to decrease in the coming year, from $0.08 to ($1.13) per share.Price to Earnings Ratio vs. the MarketThe P/E ratio of Prothena is -10.95, 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 -10.95, which means that its earnings are negative and its P/E ratio cannot be compared to companies with positive earnings.Price to Earnings Growth RatioProthena has a PEG Ratio of 3.36. PEG Ratios above 1 indicate that a company could be overvalued.Price to Book Value per Share RatioProthena has a P/B Ratio of 1.76. P/B Ratios below 3 indicates that a company is reasonably valued with respect to its assets and liabilities.Read more about Prothena's valuation and earnings. Short Interest0.0 / 5Short Interest LevelBearish Percentage of Shares Shorted18.22% of the float of Prothena has been sold short.Short Interest Ratio / Days to CoverProthena has a short interest ratio ("days to cover") of 19.56, which indicates bearish sentiment.Change versus previous monthShort interest in Prothena has recently increased by 4.56%, indicating that investor sentiment is decreasing. 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. News and Social Media4.7 / 5News Sentiment1.45 News SentimentProthena has a news sentiment score of 1.45. 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 higher news sentiment than the 0.75 average news sentiment score of Healthcare companies.News Coverage This WeekMarketBeat has tracked 4 news articles for Prothena this week, compared to 2 articles on an average week.Search Interest1 people have searched for PRTA on MarketBeat in the last 30 days. MarketBeat Follows4 people have added Prothena to their MarketBeat watchlist in the last 30 days. Company Ownership3.9 / 5Insider TradingAcquiring Shares Net Insider BuyingOver the last three months, insiders have purchased a net $1,738,513.00 in company stock, which represents 0.3614% of the company's market cap.Insider Buying vs. Insider SellingIn the past three months, Prothena insiders have bought 1,279.00% more of their company's stock than they have sold. Specifically, they have bought $1,874,440.00 in company stock and sold $135,927.00 in company stock.Percentage Held by Insiders10.40% of the stock of Prothena is held by insiders. A high percentage of insider ownership can be a sign of company health.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. Submit View SMS TermsSMS is currently available in Australia, Belgium, Canada, France, Germany, Ireland, Italy, New Zealand, the Netherlands, Singapore, South Africa, Spain, Switzerland, the United Kingdom, and the United States. By entering your phone number and clicking the sign-up button, you agree to receive periodic text messages from MarketBeat at the phone number you submitted, including texts that may be sent using an automatic telephone dialing system. Message and data rates may apply. Message frequency will vary. 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Google signed on, Gates invested, and the Pentagon made it a priority. One company has been quietly building this infrastructure for sixty years.September 10 at 1:00 AM | Behind the Markets (Ad)Prothena (NASDAQ:PRTA) Major Shareholder William Scully Purchases 50,000 SharesAugust 22, 2026 | insidertrades.comRBC Capital Keeps Their Hold Rating on Prothena (PRTA)August 8, 2026 | theglobeandmail.comProthena: Q2 Earnings SnapshotAugust 6, 2026 | chron.comProthena Reports Second Quarter 2026 Financial Results and Business HighlightsAugust 6, 2026 | businesswire.comProthena to Report Second Quarter 2026 Financial Results on August 6July 30, 2026 | finance.yahoo.comSee More Headlines PRTA Stock Analysis - Frequently Asked Questions How have PRTA shares performed this year? Prothena's stock was trading at $9.55 at the beginning of the year. Since then, PRTA shares have decreased by 3.8% and is now trading at $9.19. How were Prothena's earnings last quarter? Prothena Corporation plc (NASDAQ:PRTA) issued its earnings results on Thursday, August, 6th. The biotechnology company reported ($0.32) earnings per share for the quarter, topping the consensus estimate of ($0.39) by $0.07. The biotechnology company earned $1.01 million during the quarter, compared to analyst estimates of $0.42 million. Prothena had a negative trailing twelve-month return on equity of 16.45% and a negative net margin of 80.68%. Who are Prothena's major shareholders? Prothena's top institutional shareholders include Squarepoint Ops LLC (0.43%), Hennion & Walsh Asset Management Inc. (0.17%), Assenagon Asset Management S.A. (0.12%) and Public Employees Retirement System of Ohio (0.08%). Insiders that own company stock include William P Scully, Anne Evans Kingston, Michael John Isaacs, 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 Earnings8/06/2026Today9/10/2026H.C. Wainwright 28th Annual Global Investment Conference9/16/2026Next Earnings (Estimated)11/05/2026Fiscal Year End12/31/2026Get Stock Alerts Health Indicator TradeSmith's Health IndicatorA long-term volatility-based measure designed for securities held 12 months or longer.Green: Strong and healthy uptrend with normal pullbacks.Yellow: Significant pullback but still within expected volatility.Red: Dropped beyond expected volatility; considered unhealthy. Green Zone (1m+) 1-Year History Sep 25 Dec 25 Mar 26 Jun 26 Sep 26 PRTA's financial health is in the Green zone, according to TradeSmith. PRTA has been in this zone for over one month. Industry, Sector and Symbol Stock ExchangeNASDAQ SectorHealthcare Industry Biotechnology Sub-IndustryBiotechnology Current SymbolNASDAQ:PRTA CIK1559053 Webwww.prothena.com Phone(531) 236-2500Fax353-1902-3510Employees130Year Founded2012Price Target and Rating Average Price Target for Prothena$24.57 High Price Target$36.00 Low Price Target$12.00 Potential Upside/Downside+169.9%Consensus RatingModerate Buy Rating Score (0-4)2.75 Research Coverage8 Analysts Profitability EPS (Trailing Twelve Months)($0.84) Trailing P/E RatioN/A Forward P/E Ratio113.81 P/E Growth3.36Net Income-$244.09 million Net Margins-80.68% Pretax Margin-81.33% Return on Equity-16.45% Return on Assets-14.51% Debt Debt-to-Equity RatioN/A Current Ratio25.05 Quick Ratio25.05 Sales & Book Value Annual Sales$9.68 million Price / Sales49.24 Cash FlowN/A Price / Cash FlowN/A Book Value$5.21 per share Price / Book1.75Miscellaneous Outstanding Shares52,350,000Free Float46,908,000Market Cap$476.65 million OptionableOptionable Beta-0.33 Social Links The 7 Hottest IPO Stories of 2026MarketBeat just released its list of the 7 hottest IPOs expected to hit Wall Street in 2026. 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