Prothena Corporation plc (PRTA:NASDAQ) closed at $8.24 on October 22, 2026, up 2.62% on the day. The stock trades 30.2% below its 52-week high of $11.80 and 6.6% above its 52-week low of $7.73. Over the past year, it lost 18.7%. Prothena Corporation plc is part of the Health Care sector (Major Pharmaceuticals).
In 252 trading sessions since October 21, 2025, PRTA closed higher on 115 days (46%). Its best day was March 2, 2026 (+8.42%) and its worst was May 11, 2026 (-9.88%). It never moved 10% or more in a single session. It opened at least 5% above the previous day's high 1 time.
Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on the discovery, development, and commercialization of novel immunotherapies for the treatment of diseases that involve protein misfolding or cell adhesion. It is developing antibody-based product candidates that include NEOD001, a monoclonal antibody that is in Phase III and Phase IIb clinical trials for the treatment of AL amyloidosis; PRX002 that has completed Phase Ib clinical trial for treating Parkinson's disease and other related synucleinopathies; PRX003, a monoclonal antibody that is in Phase Ib for the treatment of psoriasis and other inflammatory diseases; and PRX004, a monoclonal antibody that is under preclinical development. The company 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 alpha-synuclein. Prothena Corporation plc was incorporated in 2012 and is headquartered in Dun Laoghaire, Ireland.
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