Option Greeks measure how an option's price responds to changes in the stock price (delta and gamma), time (theta), implied volatility (vega), and interest rates (rho).

Gamma, theta, and vega are largest for strikes near the Prothena stock price and shrink for strikes far above or below it. Theta grows as expiration gets closer, while vega is larger for expirations further out. Call delta runs from 0 to 1 and put delta from -1 to 0, near 0.50 and -0.50 at the money, and roughly estimates the chance that an option finishes in the money.

Prothena IV rank is 72, so implied volatility is in the upper part of its one-year range. Higher implied volatility raises option premiums and daily time decay (theta), and spreads delta and gamma across a wider range of strikes. Over the past year, 30-day implied volatility ranged from 42.7% to 282.4%. See the PRTA implied volatility history for a longer view.

Across all open Prothena options on Nov 4, 2026, net gamma exposure was $57.97K and net delta exposure was $1.67M per 1% move in the stock. The PRTA gamma exposure chart shows where that gamma sits by strike.

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.