Prothena (PRTA) Stock Price, News & Analysis

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.

Key Stats

• Today's Range: $8.77 to $9.14
• 50-Day Range: $8.12 to $9.85
• 52-Week Range: $7.73 to $11.80
• Volume: 376,273 shs
• Average Volume: 317,599 shs
• Market Capitalization: $467.49 million
• P/E Ratio: N/A
• Dividend Yield: N/A
• Price Target: $24.57
• Consensus Rating: Moderate Buy

Prothena Stock Analysis - MarketRank™

Prothena scored higher than 62% of companies evaluated by MarketBeat, and ranked 347th out of 904 stocks in the healthcare sector. Scores are calculated by averaging available category scores, with extra weight given to analysis and valuation.

Analyst's Opinion

• Score: 4.0 / 5
• Analyst Rating: Moderate Buy

Consensus Rating

Prothena 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 Potential

Prothena has a consensus price target of $24.57, representing about 175.2% upside from its current price of $8.93.

Amount of Analyst Coverage

Prothena has only been the subject of 3 research reports in the past 90 days.

Earnings and Valuation

• Score: 0.0 / 5
• Proj. Earnings Growth: Decreasing

Earnings Growth

Earnings for Prothena are expected to decrease in the coming year, from $0.08 to ($1.13) per share.

Price to Earnings Ratio vs. the Market

The P/E ratio of Prothena is -10.63, 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 -10.63, which means that its earnings are negative and its P/E ratio cannot be compared to companies with positive earnings.

Price to Earnings Growth Ratio

Prothena has a PEG Ratio of 3.15. PEG Ratios above 1 indicate that a company could be overvalued.

Price to Book Value per Share Ratio

Prothena has a P/B Ratio of 1.71. P/B Ratios below 3 indicates that a company is reasonably valued with respect to its assets and liabilities.

Short Interest

• Score: 1.0 / 5
• Short Interest Level: Bearish

Percentage of Shares Shorted

18.11% 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 24.85, which indicates bearish sentiment.

Change versus previous month

Short interest in Prothena has recently decreased by 0.58%, indicating that investor sentiment is improving.

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.

News and Social Media

• Score: 3.1 / 5
• News Sentiment: 0.93

News Sentiment

Prothena has a news sentiment score of 0.93. 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 news sentiment score is similar to the average news sentiment of Healthcare companies.

News Coverage This Week

MarketBeat has tracked 2 news articles for Prothena this week, compared to 2 articles on an average week.

Search Interest

1 people have searched for PRTA on MarketBeat in the last 30 days.

MarketBeat Follows

4 people have added Prothena to their MarketBeat watchlist in the last 30 days. This is an increase of 300% compared to the previous 30 days.

Company Ownership

• Score: 3.9 / 5
• Insider Trading: Acquiring Shares

Net Insider Buying

Over the last three months, insiders have purchased a net $717,263.00 in company stock, which represents 0.1534% of the company's market cap.

Insider Buying vs. Insider Selling

In the past three months, Prothena insiders have bought 527.68% more of their company's stock than they have sold. Specifically, they have bought $853,190.00 in company stock and sold $135,927.00 in company stock.

Percentage Held by Insiders

10.40% 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 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.

Company Calendar

• Last Earnings: 8/06/2026
• Today: 9/13/2026
• H.C. Wainwright 28th Annual Global Investment Conference: 9/16/2026
• Next Earnings (Estimated): 11/05/2026
• Fiscal Year End: 12/31/2026

Industry, Sector and Symbol

• Stock Exchange: NASDAQ
• Sector: Healthcare
• Industry: Biotechnology
• Sub-Industry: Biotechnology
• Current Symbol: NASDAQ:PRTA
• CIK: 1559053
• Web: www.prothena.com
• Phone: (531) 236-2500
• Fax: 353-1902-3510
• Employees: 130
• Year Founded: 2012

Price Target and Rating

• Average Price Target for Prothena: $24.57
• High Price Target: $36.00
• Low Price Target: $12.00
• Potential Upside/Downside: +175.2%
• Consensus Rating: Moderate Buy
• Rating Score (0-4): 2.75
• Research Coverage: 8 Analysts

Profitability

• EPS (Trailing Twelve Months): ($0.84)
• Trailing P/E Ratio: N/A
• Forward P/E Ratio: 111.63
• P/E Growth: 3.15
• Net 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 Ratio: N/A
• Current Ratio: 25.05
• Quick Ratio: 25.05

Sales & Book Value

• Annual Sales: $9.68 million
• Price / Sales: 48.29
• Cash Flow: N/A
• Price / Cash Flow: N/A
• Book Value: $5.21 per share
• Price / Book: 1.71

Miscellaneous

• Outstanding Shares: 52,350,000
• Free Float: 46,908,000
• Market Cap: $467.49 million
• Optionable: Optionable
• Beta: -0.33