Go Pro
NASDAQ:PRTA

Prothena (PRTA) Stock Price, News & Analysis

Prothena logo
$8.86 -0.22 (-2.42%)
Closing price 08/14/2026 04:00 PM Eastern
Extended Trading
$8.85 -0.01 (-0.11%)
As of 08/14/2026 07:34 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 Massive. Learn more.

About Prothena Stock (NASDAQ:PRTA)

Advanced

Key Stats

Today's Range
$8.84
$9.15
50-Day Range
$7.91
$10.02
52-Week Range
$7.73
$11.80
Volume
312,600 shs
Average Volume
527,303 shs
Market Capitalization
$463.85 million
P/E Ratio
N/A
Dividend Yield
N/A
Price Target
$23.75
Consensus Rating
Moderate 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.

Prothena Stock Analysis - MarketRank™

See Top-Rated MarketRank™ Stocks
62nd Percentile Overall Score

PRTA MarketRank™: 

Prothena scored higher than 62% of companies evaluated by MarketBeat, and ranked 335th out of 912 stocks in the healthcare sector. Scores are calculated by averaging available category scores, with extra weight given to analysis and valuation.

  • 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 $23.75, representing about 168.1% upside from its current price of $8.86.

  • Amount of Analyst Coverage

    Prothena 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 Growth

    Earnings for Prothena are expected to decrease in the coming year, from $0.08 to ($1.21) per share.

  • Price to Earnings Ratio vs. the Market

    The P/E ratio of Prothena is -10.55, 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 -10.55, 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 3.00. 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 1.62. P/B Ratios below 3 indicates that a company is reasonably valued with respect to its assets and liabilities.

  • Percentage of Shares Shorted

    17.42% 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 13.96, which indicates bearish sentiment.
  • Change versus previous month

    Short interest in Prothena has recently decreased by 0.30%, indicating that investor sentiment is improving.
  • Dividend Yield

    Prothena does not currently pay a dividend.

  • Dividend Growth

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

  • News Sentiment

    Prothena has a news sentiment score of 0.66. 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 8 news articles for Prothena this week, compared to 2 articles on an average week.
  • MarketBeat Follows

    2 people have added Prothena to their MarketBeat watchlist in the last 30 days. This is an increase of 100% compared to the previous 30 days.
  • Net Insider Buying

    Over the last three months, insiders have purchased a net $2,961,323.00 in company stock, which represents 0.6385% of the company's market cap.

  • Insider Buying vs. Insider Selling

    In the past three months, Prothena insiders have bought 2,178.61% more of their company's stock than they have sold. Specifically, they have bought $3,097,250.00 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.

  • 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.

SMS 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. Messages will consist of stock alerts, news stories, and partner advertisements/offers. Consent is not a condition of the purchase of any goods or services. Text HELP for help/customer support. Unsubscribe at any time by replying "STOP" to any text message that you receive from MarketBeat or by visiting our mailing preferences page. Read our full terms of service and privacy policy.

PRTA Stock News Headlines

HC Wainwright Issues Positive Forecast for Prothena Earnings
RBC Capital Keeps Their Hold Rating on Prothena (PRTA)
The dollar just broke
Bloomberg research shows the U.S. dollar's share of global reserves has fallen to the lowest level this century — and the consequences for your savings and investments could be severe. President Trump has signed executive order 14241 to initiate the first full reset of the American dollar in 50 years. A new monetary anchor is being established — one that's not gold or crypto, but something far more unexpected that Vladimir Putin once called the key to world leadership.tc pixel
Prothena: Q2 Earnings Snapshot
Prothena (PRTA) to Post Earnings on Thursday
See More Headlines

PRTA Stock Analysis - Frequently Asked Questions

Prothena's stock was trading at $9.55 at the beginning of 2026. Since then, PRTA stock has decreased by 7.2% and is now trading at $8.86.

Prothena Corporation plc (NASDAQ:PRTA) released its quarterly earnings results on Thursday, August, 6th. The biotechnology company reported ($0.32) EPS for the quarter, beating the consensus estimate of ($0.39) by $0.07. The biotechnology company had revenue of $1.01 million for the quarter, compared to the consensus estimate 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%.

Prothena's top institutional investors include Hennion & Walsh Asset Management Inc. (0.17%), Assenagon Asset Management S.A. (0.12%) and Great Lakes Advisors LLC (0.05%). 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
.

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.

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 Earnings
8/06/2026
Today
8/16/2026
Fiscal Year End
12/31/2026

Industry, Sector and Symbol

Stock Exchange
NASDAQ
Industry
Biotechnology
Sub-Industry
Biotechnology
Current Symbol
NASDAQ:PRTA
CIK
1559053
Employees
130
Year Founded
2012

Price Target and Rating

High Price Target
$36.00
Low Price Target
$12.00
Potential Upside/Downside
+168.1%
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
110.75
P/E Growth
3
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
8.51
Cash Flow
N/A
Price / Cash Flow
N/A
Book Value
$5.48 per share
Price / Book
1.62

Miscellaneous

Outstanding Shares
52,353,000
Free Float
46,908,000
Market Cap
$463.85 million
Optionable
Optionable
Beta
-0.30

Social Links

Options Trading Made Easy - Download Now Cover

Learn the basics of options trading and how to use them to boost returns and manage risk with this free report from MarketBeat. Click the link below to get your free copy.

Get This Free Report

This page (NASDAQ:PRTA) was last updated on 8/16/2026 by MarketBeat.com Staff.
From Our Partners