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StockVS

NASDAQ · Biotechnology · USD

Prothena Corporation plc (PRTA) Stock Analysis

Prothena Corporation plc (PRTA) is a Biotechnology stock listed on NASDAQ and quoted in US Dollar.

Last Updated: October 21, 2026

PRTA

$8.03

−$0.47 (−5.53%)

Oct 21, 2026 · Market close

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Price History

Hover for the daily close. The dotted line marks the period open.

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PRTA Key Statistics

As of Oct 21, 2026
Trading
Open
$8.47
Previous Close
$8.50
Day's Range
8.01–8.54
52-Week Range
7.73–11.80
Volume
461.39K
BetaHow much the share price moves relative to the wider market. 1.0 moves in line with it; above 1.0 swings more, below 1.0 less.
−0.29
Valuation
Market Cap
$412.24M
P/E Ratio
unprofitable
P/S ratioMarket value divided by annual revenue. Useful for companies that are not yet profitable, where a P/E cannot be calculated.
7.56
EPS (ttm)Profit attributable to each share over the last twelve months.
−0.82
Financials (FY)
Revenue (FY)
$9.68M−92.83%
Net Income (FY)
−$244.09M
Profit marginThe share of revenue left as profit after all costs and taxes.
−80.68%
Shares OutstandingThe total number of shares held by all investors. Market value is this figure multiplied by the share price.
51.34M
1-Year Return
−21.39%
Dividend and dates
Earnings Date
November 5, 2026estimated
Avg Volume
483.66K

Only metrics the company reports are shown. Data provided by Yahoo Finance via yfinance. Updated daily.

Key facts

As of October 21, 2026, PRTA closed at $8.03, −21.39% over 1 year.

Prothena Corporation plc (PRTA) has a market capitalization of $412.24M.

In fiscal 2025, PRTA reported revenue of $9.68M.

PRTA Stock Return by Calendar Year

Prothena Corporation plc (PRTA) 10-year return: what $10,000 became

1 year
$10,000 $7,861
−21.39%
5 years
$10,000 $1,313
−86.87%
10 years
$10,000 $1,474
−85.26%

If you had invested $10,000 in Prothena Corporation plc (PRTA) 10 years ago, at the close on October 21, 2016, it would have been worth $1,474 at the close on October 21, 2026: −85.26% in total, −17.42% a year. A historical calculation from closing prices adjusted for splits and dividends, before fees and taxes.

Calendar-year returns computed from daily closing prices. Partial years are shown muted and marked with an asterisk.

YearReturn
2026 (partial year)−15.92%
2025−31.05%
2024−61.89%
2023−39.68%
2022+21.96%
2021+311.32%
2020−24.13%
2019+53.69%
2018−72.53%
2017−23.79%
2016 (partial year)−13.21%

As of October 21, 2026.

PRTA Revenue and Earnings by Fiscal Year

FY ends December
Fiscal yearRevenueNet incomeNet margin
2025$9.68M−$244.09M−2,520.6%
2024$135.16M−$122.31M−90.5%
2023$91.37M−$147.03M−160.9%
2022$53.91M−$116.95M−217.0%
Fiscal yearRevenueGross profitOperating incomeNet incomeNet margin
2025$9.68M—−$184.56M−$244.09M−2,520.6%
2024$135.16M—−$154.56M−$122.31M−90.5%
2023$91.37M—−$191.04M−$147.03M−160.9%
2022$53.91M—−$131.56M−$116.95M−217.0%

Annual figures as reported, in the company's reporting currency. As of December 31, 2025.

PRTA Valuation vs Biotechnology Median

Median of 608 stocks
MetricPRTABiotechnology medianvs median
P/S ratio7.5613.3043% below
Profit margin−80.68%−38.31%42.4 pts below

Medians across 608 Biotechnology stocks that report the metric. Medians, not averages, so one outlier cannot move them. As of October 21, 2026.

Recent News

News provided by third-party sources. Not financial advice.

Analysis

Data-derived

Company Overview

Prothena Corporation plc (PRTA) is capitalised at $412.24M on the latest close. The company sits in the Healthcare sector, in the Biotechnology industry. The company reports 67 employees.

The most recent close on file for PRTA is $8.03, dated October 21, 2026. That is −$0.47 (−5.53%) against the previous close. Over the past 52 weeks the price has ranged from $7.73 to $11.80. The latest close sits 3.88% above that 52-week low.

Financial Health

The most recent full year on file, fiscal 2025, shows revenue of $9.68M. Against the prior fiscal year total of $135.16M, that is a change of −92.83%. The same year closed with a net loss of $244.09M. Profit margin runs at −80.68%. That is 42.4 percentage points below the Biotechnology median of −38.31%. Trailing earnings per share are −0.82.

Across the 4 fiscal years on file, revenue moves from $53.91M in 2022 to $9.68M in 2025. Of those 4 years, 0 report positive net income.

Valuation Assessment

No trailing P/E applies: the last reported earnings figure is negative. The price-to-sales ratio is 7.56. On price-to-sales that is 43.15% below the Biotechnology median of 13.3. The medians here are taken across 608 Biotechnology companies that report the metric.

The trailing one-year total return is −21.39%. Across 10 years the annualized return works out at −17.42%. Beta against the wider market is reported at −0.29. Annualized volatility over the trailing 10 years is 75.44%.

Growth & Income

No dividend is on file for PRTA.

2026 is still running; the total return is −15.92% year to date. The strongest complete calendar year on file is 2021 at +311.32%; the weakest is 2018 at −72.53%. Of the 9 complete calendar years on file, 3 finished higher.

Peer Comparison

Prothena Corporation plc (PRTA) operates in the Biotechnology industry. Here is how it compares to its closest peers by market capitalization:

Company Ticker Market Cap P/E Ratio
Prothena Corporation plc PRTA $412.24M —
Vertex Pharmaceuticals Incorporated VRTX $132.95B 30.4
Moderna, Inc. MRNA $98.14B —
Regeneron Pharmaceuticals, Inc. REGN $82.95B 19.9

The Biotechnology industry average P/E ratio is 16.6x. Prothena Corporation plc has no P/E ratio because it is not currently profitable.

Every figure above is read from this page's own data on each daily rebuild. Informational only, not financial advice. As of October 21, 2026.

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About Prothena Corporation plc

Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation. Its product pipeline includes Prasinezumab, an investigational humanized monoclonal antibody which is in Phase 3 clinical trial for the treatment of parkinson's disease and other synucleinopathies. The company also develops Coramitug, an investigational antibody, which is in Phase 3 clinical trial for the treatment of transthyretin amyloidosis; BMS-986446, an anti-tau antibody which is in Phase 2 clinical trial to treat Alzheimer's disease; PRX019, an investigational antibody which is in Phase 1 clinical trial for the treatment of neurodegenerative diseases; and PRX123, a Dual Aß-Tau Vaccine, which is in preclinical trial for treating Alzheimer's disease. In addition, it develops discovery- and late-preclinical-stage programs include TDP-43 CYTOPE for the treatment of amyotrophic lateral sclerosis; PRX012, a next-generation anti-Aß antibody which is in phase 1 clinical trial to treat Alzheimer's disease; and PRX012-TfR, a preclinical program for the treatment of Alzheimer's disease. It 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 master collaboration agreement with Bristol Myers Squibb to develop and commercialize antibodies targeting tau, TDP-43. Prothena Corporation plc was incorporated in 2012 and is based in Dublin, Ireland.

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