Option activity is usually called unusual when a contract trades much more volume than its open interest, which can mean traders are opening new positions.

On Nov 4, 2026, Prothena options traded 1 contracts against 9.35K open, a volume to open interest ratio of 0.00, well below its 20-day average. The table above lists the contracts with the highest ratios.

Calls made up 100.0% of Prothena option volume on Nov 4, 2026, a put/call ratio of 0.00, so calls outnumber puts. The PRTA option volume chart shows calls and puts 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.