Prothena CORP Public Ltd Co: insider trades · United States · SEC (Form 4)

About Prothena CORP Public Ltd Co

Prothena Corporation plc (ticker PRTA) is a United States–listed biotechnology company trading on the NASDAQ market, with operational headquarters in Brisbane, California. The company is a late-stage clinical biopharmaceutical developer focused on protein dysregulation and misfolded-protein biology. Its investment case is built on the possibility of developing disease-modifying therapies for severe, underserved neurodegenerative disorders and rare peripheral amyloid diseases. ([sec.gov](https://www.sec.gov/Archives/edgar/data/1559053/000155905326000008/prta-20251231.htm?utm_source=openai)) Prothena was formed in 2012 as an Irish public limited company, and its ordinary shares began trading on the Nasdaq Global Market on December 21, 2012. The stock now trades on the Nasdaq Global Select Market. This structure gives the company an Irish corporate domicile while maintaining a clearly U.S.-centered operating footprint, which is common among biotech companies seeking access to U.S. capital markets and scientific talent in California. ([sec.gov](https://www.sec.gov/Archives/edgar/data/1559053/000155905326000008/prta-20251231.htm?utm_source=openai)) From an operating perspective, Prothena is a development-stage company rather than a commercial-stage drug manufacturer. Its pipeline includes wholly owned and partnered programs across Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis (ALS), and other neurodegenerative conditions, alongside rare amyloid disorders. A key element of its platform is CYTOPE®, Prothena’s proprietary technology designed to target a broad range of intracellular disease pathways in the brain and periphery. Because the company does not yet have marketed products, its long-term valuation depends primarily on clinical execution, partnering economics, and the ability to progress assets through proof-of-concept and later-stage studies. ([sec.gov](https://www.sec.gov/Archives/edgar/data/1559053/000155905326000008/prta-20251231.htm?utm_source=openai)) Competitively, Prothena occupies a specialist niche rather than competing on scale. Its differentiation lies in deep scientific expertise around protein misfolding, amyloid biology, and neurodegenerative mechanisms. Among the best-known programs are coramitug, formerly PRX004, for ATTR amyloidosis with cardiomyopathy; PRX012 and PRX123 for Alzheimer’s disease; and other neurology-focused assets. The company also retains strategic collaborations with major pharmaceutical partners such as Novo Nordisk and Bristol Myers Squibb, creating a pathway to milestone receipts and shared development risk. ([ir.prothena.com](https://ir.prothena.com/investors/press-releases/news-details/2026/Prothena-Reports-Fourth-Quarter-and-Full-Year-2025-Financial-Results-and-Provides-Financial-Guidance-and-Business-Highlights/default.aspx?utm_source=openai)) Recent news has highlighted a stronger focus on capital discipline. In 2025, Prothena announced a major corporate restructuring, including a substantial workforce reduction, to lower operating costs and concentrate resources on remaining wholly owned and partnered programs. In early 2026, the company reported cash, cash equivalents and restricted cash of $308.4 million with no debt, and it authorized a share repurchase plan of up to $100 million. It also disclosed meaningful development progress, including a U.S. FDA Fast Track designation for Novo Nordisk’s coramitug program and a $50 million milestone payment tied to the ongoing Phase 3 CLEOPATTRA study. For international investors, PRTA remains a high-risk, high-upside biotech story driven by clinical readouts, partnership milestones, and pipeline optionality rather than current product revenues. ([ir.prothena.com](https://ir.prothena.com/investors/press-releases/news-details/2025/Prothena-Announces-Corporate-Restructuring/default.aspx?utm_source=openai))