Prothena Corporation plc has authorized a Share Repurchase Plan to buy back up to $100.0 million of its outstanding ordinary shares. The plan will expire on December 31, 2026, and may be suspended or discontinued at any time, with no obligation to acquire any specific amount of shares. As of December 31, 2025, Prothena reported $308.4 million in cash, cash equivalents, and restricted cash, with no debt. The company expects to end 2026 with approximately $255 million in cash, cash equivalents, and restricted cash, excluding any repurchases. Potential clinical milestone payments of up to $105 million from strategic partners (Novo Nordisk and Bristol Myers Squibb) are anticipated in 2026.