Prothena (PRTA) Stock Price, News & Analysis

Company Overview

Prothena 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.

Key Stats

• Today's Range: $7.50 to $7.96
• 50-Day Range: $4.88 to $7.92
• 52-Week Range: $4.32 to $22.83
• Volume: 906,550 shs
• Average Volume: 1.01 million shs
• Market Capitalization: $405.88 million
• P/E Ratio: N/A
• Dividend Yield: N/A
• Price Target: $30.25
• Consensus Rating: Hold

Prothena Stock Analysis - MarketRank™

Prothena scored higher than 59% of companies evaluated by MarketBeat, and ranked 351st out of 935 stocks in the medical sector. Scores are calculated by averaging available category scores, with extra weight given to analysis and valuation.

Analyst's Opinion

• Score: 4.2 / 5
• Analyst Rating: Hold

Consensus Rating

Prothena 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 Coverage

Prothena has been the subject of 9 research reports in the past 90 days, demonstrating strong analyst interest in this stock.

Earnings and Valuation

• Score: 0.6 / 5
• Proj. Earnings Growth: Growing

Earnings Growth

Earnings for Prothena are expected to grow in the coming year, from ($4.04) to ($3.33) per share.

Price to Earnings Ratio vs. the Market

The P/E ratio of Prothena is -1.34, 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. Sector

The P/E ratio of Prothena is -1.34, 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 Ratio

Prothena has a P/B Ratio of 1.25. P/B Ratios below 3 indicates that a company is reasonably valued with respect to its assets and liabilities.

Short Interest

• Score: 2.0 / 5
• Short Interest Level: Bearish

Percentage of Shares Shorted

11.25% of the float of Prothena has been sold short.

Short Interest Ratio / Days to Cover

Prothena has a short interest ratio ("days to cover") of 2.7, which is generally considered an acceptable ratio of short interest to trading volume.

Change versus previous month

Short interest in Prothena has recently increased by 9.93%, indicating that investor sentiment is decreasing significantly.

Dividend

• Score: 0.0 / 5
• Dividend Strength: N/A

Dividend Yield

Prothena does not currently pay a dividend.

Dividend Growth

Prothena does not have a long track record of dividend growth.

Sustainability and ESG

• Score: N/A
• Environmental Score: N/A

Percentage of Shares Shorted

11.25% of the float of Prothena has been sold short.

Short Interest Ratio / Days to Cover

Prothena has a short interest ratio ("days to cover") of 2.7, which is generally considered an acceptable ratio of short interest to trading volume.

Change versus previous month

Short interest in Prothena has recently increased by 9.93%, indicating that investor sentiment is decreasing significantly.

News and Social Media

• Score: 2.3 / 5
• News Sentiment: 0.19

News Sentiment

Prothena has a news sentiment score of 0.19. 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 0.75 average news sentiment score of Medical companies.

News Coverage This Week

MarketBeat has tracked 22 news articles for Prothena this week, compared to 4 articles on an average week.

MarketBeat Follows

1 people have added Prothena to their MarketBeat watchlist in the last 30 days.

Company Ownership

• Score: 1.7 / 5
• Insider Trading: N/A

Insider Buying vs. Insider Selling

In the past three months, Prothena insiders have not sold or bought any company stock.

Percentage Held by Insiders

Only 9.20% of the stock of Prothena is held by insiders.

Percentage Held by Institutions

97.08% of the stock of Prothena is held by institutions. High institutional ownership can be a signal of strong market trust in this company.

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 45.6% and is now trading at $7.54.

How were Prothena's earnings last quarter?

Prothena Corporation plc (NASDAQ:PRTA) announced its quarterly earnings data on Monday, August, 4th. The biotechnology company reported ($1.86) earnings per share (EPS) for the quarter, missing the consensus estimate of ($1.11) by $0.75. The biotechnology company earned $4.42 million during the quarter, compared to analysts' expectations of $5.36 million. Prothena had a negative trailing twelve-month return on equity of 62.17% and a negative net margin of 2,929.30%.

Who are Prothena's major shareholders?

Prothena's top institutional investors include Acadian Asset Management LLC (1.89%), Geode Capital Management LLC (1.73%), Nordea Investment Management AB (0.58%) and Simplex Trading LLC. 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 AU Optronics (AUOTY).

Company Calendar

• Last Earnings: 8/04/2025
• Today: 8/12/2025
• Fiscal Year End: 12/31/2025

Industry, Sector and Symbol

• Stock Exchange: NASDAQ
• Sector: Medical
• Industry: MED - BIOMED/GENE
• Sub-Industry: Pharmaceutical Products
• Current Symbol: NASDAQ:PRTA
• CIK: 1559053
• Web: www.prothena.com
• Phone: (531) 236-2500
• Fax: 353-1902-3510
• Employees: 130
• Year Founded: N/A

Price Target and Rating

• Average Price Target for Prothena: $30.25
• High Price Target: $81.00
• Low Price Target: $6.00
• Potential Upside/Downside: +301.2%
• Consensus Rating: Hold
• Rating Score (0-4): 2.33
• Research Coverage: 9 Analysts

Profitability

• EPS (Trailing Twelve Months): ($5.64)
• Trailing P/E Ratio: N/A
• Forward P/E Ratio: N/A
• P/E Growth: N/A
• Net Income: -$122.31 million
• Net Margins: -2,929.30%
• Pretax Margin: -2,530.46%
• Return on Equity: -62.17%
• Return on Assets: -54.43%

Debt

• Debt-to-Equity Ratio: N/A
• Current Ratio: 5.68
• Quick Ratio: 5.68

Sales & Book Value

• Annual Sales: $135.16 million
• Price / Sales: 3.00
• Cash Flow: N/A
• Price / Cash Flow: N/A
• Book Value: $6.03 per share
• Price / Book: 1.25

Miscellaneous

• Outstanding Shares: 53,830,000
• Free Float: 48,878,000
• Market Cap: $405.88 million
• Optionable: Optionable
• Beta: -0.03