Form 4 Filing by William P. Scully

William P. Scully, a 10% owner of PROTHENA CORP PUBLIC LTD CO (PRTA), reported transactions on October 13 and 14, 2026. On October 13, 2026, 100,000 shares of ordinary stock were acquired at a weighted average price of $8.3548, with prices ranging from $8.2547 to $8.4616. On October 14, 2026, an additional 10,000 shares were acquired at a weighted average price of $8.4569, with prices ranging from $8.4000 to $8.5600. Following these transactions, the post-transaction shares owned directly by Mr. Scully amount to 1,037,000. Additionally, Mr. Scully has indirect ownership of 529,000 shares through his spouse and 187,000 shares through Manatee Equity Fund LLC. The filing was signed by Reid E. Buchanan by Power of Attorney from William P. Scully on October 15, 2026.