NASDAQ:PRTA Prothena (PRTA) Stock Price, News & Analysis $5.72 -0.03 (-0.52%) Closing price 06/20/2025 04:00 PM EasternExtended Trading$5.83 +0.11 (+1.91%) As of 06/20/2025 07:46 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$5.64▼$6.0550-Day Range$4.58▼$9.9452-Week Range$4.32▼$25.42Volume3.57 million shsAverage Volume765,891 shsMarket Capitalization$307.89 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™ Stocks72nd Percentile Overall ScorePRTA MarketRank™: Prothena scored higher than 72% of companies evaluated by MarketBeat, and ranked 270th out of 926 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 -2.75, 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 -2.75, 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 0.63. 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 Interest4.0 / 5Short Interest LevelHealthy Percentage of Shares Shorted10.42% of the float of Prothena has been sold short.Short Interest Ratio / Days to CoverProthena has a short interest ratio ("days to cover") of 3.3, which is generally considered an acceptable ratio of short interest to trading volume.Change versus previous monthShort interest in Prothena has recently decreased by 50.73%, indicating that investor sentiment is improving 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 Shorted10.42% of the float of Prothena has been sold short.Short Interest Ratio / Days to CoverProthena has a short interest ratio ("days to cover") of 3.3, which is generally considered an acceptable ratio of short interest to trading volume.Change versus previous monthShort interest in Prothena has recently decreased by 50.73%, indicating that investor sentiment is improving significantly. News and Social Media1.9 / 5News Sentiment0.44 News SentimentProthena has a news sentiment score of 0.44. 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 0.65 average news sentiment score of Medical companies.News Coverage This WeekMarketBeat has tracked 10 news articles for Prothena this week, compared to 4 articles on an average week. 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 HeadlinesProthena (NASDAQ:PRTA) Earns Neutral Rating from Cantor FitzgeraldJune 21 at 1:57 AM | americanbankingnews.comProthena Corp (PRTA) Receives Reiterated Neutral Rating from Cantor Fitzgerald | PRTA Stock NewsJune 20 at 10:18 AM | gurufocus.comNew Rule Hits in July — The Smart Money Already MovedA little-known regulation quietly goes into effect this July. And it's already being exploited by Wall Street and the Big Banks… It gives them the green light to treat a certain tangible asset as equivalent to cold, hard cash. Not stocks. Not real estate. And definitely not the U.S. dollar. We're talking about something they don't want you to notice — because the fewer people who act on this, the better it is for them.June 21, 2025 | American Alternative (Ad)Roche’s Phase 3 Move Boosts Outlook for Prothena Corporation plc (PRTA)June 19 at 1:10 AM | finance.yahoo.comProthena Announces Corporate RestructuringJune 18 at 4:51 PM | finance.yahoo.comRoche’s Phase 3 Move Boosts Outlook for Prothena Corporation plc (PRTA)June 17, 2025 | msn.comProthena’s Partner Roche to Advance Prasinezumab into Phase III Development for Early-Stage Parkinson's DiseaseJune 16, 2025 | uk.finance.yahoo.comProthena's Partner Roche to Advance Prasinezumab into Phase III Development for Early-Stage Parkinson's DiseaseJune 16, 2025 | businesswire.comSee More Headlines PRTA Stock Analysis - Frequently Asked Questions How have PRTA shares performed this year? Prothena's stock was trading at $13.85 on January 1st, 2025. Since then, PRTA stock has decreased by 58.7% and is now trading at $5.72. View the best growth stocks for 2025 here. How were Prothena's earnings last quarter? Prothena Corporation plc (NASDAQ:PRTA) posted its quarterly earnings data on Thursday, May, 8th. The biotechnology company reported ($1.12) EPS for the quarter, missing the consensus estimate of ($0.92) by $0.20. The firm's quarterly revenue was up 5500.0% compared to the same quarter last year. Who are Prothena's major shareholders? Prothena's top institutional investors 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, Karin L Walker, Hideki Garren, Brandon S Smith, Carol D Karp, Wagner M Zago and Michael J Malecek. 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 AU Optronics (AUOTY). Company Calendar Last Earnings5/08/2025Today6/21/2025Next Earnings (Estimated)8/06/2025Fiscal Year End12/31/2025Get Stock AlertsIndustry, Sector and Symbol Stock ExchangeNASDAQ SectorMedical Industry MED - BIOMED/GENE 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+450.7%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-$122.31 million Net Margins-79.94% Pretax Margin-84.00% Return on Equity-21.61% Return on Assets-19.32% Debt Debt-to-Equity RatioN/A Current Ratio9.00 Quick Ratio9.00 Sales & Book Value Annual Sales$137.94 million Price / Sales2.23 Cash FlowN/A Price / Cash FlowN/A Book Value$9.05 per share Price / Book0.63Miscellaneous Outstanding Shares53,827,000Free Float48,875,000Market Cap$307.89 million OptionableOptionable Beta-0.08 A Beginner's Guide to Investing in CannabisUnlock your free copy of MarketBeat's comprehensive guide to pot stock investing and discover which cannabis companies are poised for growth. 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