PRTA Stock — Prothena Corporation plc

Prothena Corporation plc (PRTA)

Updated October 16, 2026.

PRTA is a Stock. Total return is 16.0% over the past 13.8 years, 558.8 points behind SPY at 574.8%.

Prothena Corporation plc is a late-stage clinical biotechnology company developing novel therapies for diseases caused by protein dysregulation, with a pipeline focused on neurodegenerative conditions including Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis; the company has partnerships with Roche for synuclein-targeting antibodies and with Bristol Myers Squibb for tau and TDP-43 targeting programs. The company does not currently distribute to shareholders. Prothena is oriented toward investors seeking exposure to clinical-stage biotechnology development rather than current income.

PRTA performance versus SPY

Price and return data through 2026-10-16.

Total return is 16.0% over the past 13.8 years, 558.8 points behind SPY at 574.8%. Over the past year its total return — price change plus distributions reinvested — is -17.2%. Its deepest 1-year drawdown was 31.3%.

PRTA key facts

Asset type

Stock

Asset class

Equity

Inception date

12/21/2012

Distribution frequency

None

Last close

$8.35 (as of 2026-10-16)

Market cap

$428,663,733

Average volume

670256.0

Beta

-0.292

Payout ratio

0.0%

Forward P/E

10.627

EPS

$-0.83

How Dividend Vision calculates yield and returns

Distribution rate (the posted rate) uses calculation basis unavailable. Issuer rates can use a different denominator and date, including ex-date NAV. Trailing-12-month yield is the sum of split-adjusted cash distributions with ex-dates in the last 12 months, divided by the published price. It lags a recent raise or cut. Total return uses split-adjusted close with distributions reinvested on the ex-dividend date (a modeling convention, not the cash-settlement date) from the first stored bar on or after inception through the latest bar, compared with the same window on the benchmark. That is the security's total return, not your personal gain/loss.

Yield and safety methodology · Distribution rate methodology · Distribution Safety Score methodology

Sources and review

Primary sources: prices and distributions from Dividend Vision, derived from vendor EOD data.

Reviewed by Bert Sweet, CEO and Co-owner of Dividend Vision. Methodology: Distribution Safety Score.

PRTA risks and drawbacks

Total return has trailed SPY over the available window. The deepest 1-year drawdown on record here is 31.3%.

Who may consider PRTA — and who may not

It is a weaker fit for investors who need monthly cash flow (PRTA does not currently distribute); investors whose main goal is matching SPY total return. This is educational context, not a recommendation to buy or sell.

More on PRTA

• All tickers starting with P

Tagged: Healthcare.

Frequently asked questions