Prothena PLC - (PRTA) closed at $8.35 on October 16, 2026, down 1.8% from the previous close, on volume of 645,045 shares (30-day average 506,393).
Data as of October 16, 2026.
16-Oct-2026
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Prothena Corp PLC is a late-stage clinical biotechnology company that focuses on protein dysregulation and a pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare and peripheral amyloid diseases. Prothena is developing and applying its proprietary CYTOPE technology to target a broad spectrum of intracellular disease pathways in the brain and periphery. The company's pipeline includes both wholly-owned and partnered programs like Prasinezumab, Coramitug (PRX004), BMS-986446 (PRX005), PRX019, TDP-43 CYTOPE, and PRX012-TfR, being developed for the potential treatment of Parkinson's disease, ATTR amyloidosis with cardiomyopathy, Alzheimer's disease, Amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases.
Prothena PLC - trades on the NASDAQ stock market under the symbol PRTA.
As of October 16, 2026, PRTA stock price declined to $8.35 with 645,045 million shares trading.
PRTA has a beta of 0.71, meaning it tends to be less sensitive to market movements. PRTA has a correlation of 0.04 to the broad based SPY ETF.
PRTA has a market cap of $437.15 million. This is considered a Small Cap stock.
Last quarter Prothena PLC - reported $1 million in Revenue and -$.36 earnings per share. This beat revenue expectation by $463,336 and missed earnings estimates by -$.59.
In the last 3 years, PRTA traded as high as $53.24 and as low as $4.32.
The top ETF exchange traded funds that PRTA belongs to (by Net Assets): IWM, XBI, VXF, DFAS, IBB.
PRTA has underperformed the market in the last year with a return of -17.2%, while the SPY ETF gained +16.7%. In the last 3 month period, PRTA fell short of the market, returning -1.4%, while SPY returned +1.9%. However, in the most recent 2 weeks PRTA has outperformed the stock market by returning -0.1%, while SPY returned -0.8%.
PRTA support price is $8.19 and resistance is $8.81 (based on 1 day standard deviation move). This means that using the most recent 20 day stock volatility and applying a one standard deviation move around the stock's closing price, stastically there is a 67% probability that PRTA shares will trade within this expected range on the day.
