Prothena (PRTA) Stock Price, News & Analysis

Company Overview

Prothena Corporation plc (NASDAQ: PRTA) is a clinical-stage biotechnology company focused on discovering and developing novel therapies for neurodegenerative and other protein-misfolding diseases. The company’s research is based on targeting abnormal proteins and the biological processes associated with their accumulation in tissue.

Prothena’s lead programs include birtamimab, an investigational antibody being developed for patients with AL amyloidosis, and prasinezumab, an investigational antibody targeting alpha-synuclein for Parkinson’s disease. Prasinezumab is being developed in collaboration with Roche. The company also maintains research programs aimed at identifying additional treatments for diseases involving amyloid and other misfolded proteins.

Founded in 2012 as a spin-off of Elan Corporation, Prothena is headquartered in Dublin, Ireland, and conducts research and development activities serving international markets. Its work is primarily focused on advancing clinical-stage medicines through partnerships and internal development rather than on commercialized products.

Key Stats

• Today's Range: $8.20 to $8.50
• 50-Day Range: $8.12 to $9.85
• 52-Week Range: $7.73 to $11.80
• Volume: 398,335 shs
• Average Volume: 501,101 shs
• Market Capitalization: $431.39 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 66% of companies evaluated by MarketBeat, and ranked 274th out of 903 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 198.2% upside from its current price of $8.24.

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 -9.81, 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 -9.81, 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 3.12. 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 1.58. 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: 3.7 / 5
• News Sentiment: N/A

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 is a higher news sentiment than the 0.80 average news sentiment score of Healthcare companies.

News Coverage This Week

MarketBeat has tracked 1 news article 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

6 people have added Prothena to their MarketBeat watchlist in the last 30 days. This is an increase of 500% 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 0.1663% 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: 9/16/2026
• 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: 67
• 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: +198.2%
• 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: 103.00
• P/E Growth: 3.12
• 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: $54.53 million
• Price / Sales: 7.91
• Cash Flow: N/A
• Price / Cash Flow: N/A
• Book Value: $5.21 per share
• Price / Book: 1.58

Miscellaneous

• Outstanding Shares: 52,353,000
• Free Float: 46,908,000
• Market Cap: $431.39 million
• Optionable: Optionable
• Beta: -0.33