Prothena 10% Owner William P. Scully Reports Acquisition of $920,049 in Common Shares

Prothena 10% owner William P. Scully purchased 110,000 ordinary shares. Purchases comprised 100,000 shares at $8.3548 per share and 10,000 shares at $8.4569 per share. His direct holdings rose to 1,037,000 ordinary shares. * Indirect holdings included 529,000 ordinary shares through his spouse and 187,000 through Manatee Equity Fund. Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Prothena Corporation plc published the original content used to generate this news brief via EDGAR, the Electronic Data Gathering, Analysis, and Retrieval system operated by the U.S. Securities and Exchange Commission (Ref. ID: 0001045463-26-000021), on October 15, 2026, and is solely responsible for the information contained therein. (C)