Prothena Corp. Plc (PRTA)

Prothena's stock price experienced a significant decline of 30.04% between January 6, 2025, and January 2, 2026, impacted by the failure of a late-stage trial for birtamimab in May 2025, leading to a roughly 31% drop in shares and analyst downgrades. Following the trial failure, Prothena announced plans to evaluate business options and implement a significant workforce reduction in June 2025 to cut operational expenses. More recently, between November and December 2025, there were several analyst updates, including price target increases and a "Buy" rating initiation. The company also reported Q3 2025 earnings in November 2025, which missed estimates.

There is no direct information available indicating demand seasonality for Prothena Corp. Plc's products and services. As a clinical-stage biotechnology company, the concept of "demand seasonality" is not typically applicable until products are commercialized. Stock price seasonality analysis refers to historical stock performance patterns rather than the demand for its therapeutic products.

Prothena Corporation plc is a clinical-stage biotechnology company based in Dublin, Ireland, focused on discovering and developing novel therapies for diseases caused by protein dysregulation. The company operates within the Health Care sector, specifically in the Biotechnology and Pharmaceutical Preparations industry. Prothena's pipeline targets neurodegenerative and rare peripheral amyloid diseases, leveraging expertise in protein research, immunology, and antibody engineering. Key programs include Prasinezumab for Parkinson's disease, Coramitug for transthyretin amyloidosis, BMS-986446 for Alzheimer's disease, PRX012 for Alzheimer's disease, PRX123 for Alzheimer's disease, PRX019 for neurodegenerative diseases, Birtamimab for AL amyloidosis, and PRX005 for Alzheimer's disease.

Prothena Corporation plc is headquartered in Dublin, Ireland, and maintains significant operations in the United States. The company has a global focus, engaging in clinical development programs and regulatory activities across North America, Europe, and Asia.

Prothena's brand reputation has been shaped by both positive clinical advancements and challenging corporate events. Positive influences include the progress of partnered programs, such as Roche advancing prasinezumab into Phase III and Bristol Myers Squibb receiving Fast Track Designation for BMS-986446. However, the company's reputation was negatively impacted by the failure of the birtamimab late-stage trial in May 2025, compounded by a corporate restructuring in June 2025. Analyst ratings have been varied, with a consensus "Hold" rating reflecting a mixed outlook.

Prothena Corporation plc's ownership is primarily distributed among institutional investors, mutual funds, and individual shareholders. Institutional investors and hedge funds hold a significant portion of the stock, with approximately 97.08% held by institutions according to one source, and around 38.40% to 44.69% according to others. Insiders hold about 10.00% to 24.47% of the stock, while retail investors hold approximately 30.84%. Major institutional owners include Fmr Llc, BlackRock, Inc., and Vanguard Group Inc. Notable individual/insider shareholders include Ecor1 Capital LLC and Oleg Nodelman.