 DUBLIN, Ireland, March 23, 2021 GLOBE NEWSWIRE -- Prothena Corporation plc NASDAQ:PRTA, a late-stage clinical company with expertise in protein dysregulation and a pipeline of investigational therapeutics for rare peripheral amyloid and neurodegenerative diseases, today announced that it has commenced an underwritten public offering of its ordinary shares. All of the ordinary shares in the offering will be sold by Prothena. In addition, Prothena has granted the underwriters a 30-day option to purchase up to an additional 15 of the number of ordinary shares sold. 