SCHEDULE 13G/A 0001193125-24-035471 0001045463 XXXXXXXX LIVE 5 Ordinary Shares, $0.01 par value 09/30/2025 0001559053 PROTHENA CORP PUBLIC LTD CO G72800108 77 SIR JOHN ROGERSON'S QUAY, BLOCK C 77 SIR JOHN ROGERSON'S QUAY, BLOCK C DUBLIN 2 L2 D02 VK60 Rule 13d-1(c) SCULLY WILLIAM P FL 763000.00 4518846.00 763000.00 4518846.00 5281846.00 9.8 IN See Item 4 PROTHENA CORP PUBLIC LTD CO 77 SIR JOHN ROGERSON'S QUAY, BLOCK C, 77 SIR JOHN ROGERSON'S QUAY, BLOCK C, DUBLIN 2, IRELAND, D02 VK60. William P. Scully 771 Manatee Cove, Vero Beach, Florida 32963 Florida Y The Reporting Person may be deemed to be the beneficial owner of 5,281,846 Ordinary Shares. This amount consists of (i) 80,000 Ordinary Shares owned by Manatee Equity Fund LLC, of which the Reporting Person is the sole manager with sole voting and dispositive power, (ii) 683,000 Ordinary Shares owned by the Reporting Persons IRA, over which he has sole voting and dispositive power, (iii) 42,000 Ordinary Shares owned by the Reporting Persons spouses IRA, over which he may be deemed to have shared voting and dispositive power, (iv) 10,000 Ordinary Shares owned by the Reporting Persons spouse, over which he may be deemed to have shared voting and dispositive power (v) 23,000 Ordinary Shares owned by an IRA subject to an investment management agreement over which the Reporting Person may be deemed to have shared voting and dispositive power by reason of his right to terminate such agreement, (vii) 68,000 Ordinary Shares owned by a trust, of which the Reporting Person may be deemed to have shared voting and dispositive power by virtue of being a co-trustee, (viii) 4,335,846 Ordinary Shares owned in the aggregate by various grantor retained annuity trusts, which have an independent trustee, but over which the Reporting Person may be deemed to have shared voting and dispositive power by reason of his retained right to substitute assets in such trusts, and (ix) 40,000 Ordinary Shares owned by another trust, which has an independent trustee, but over which the Reporting Person may be deemed to have shared voting and dispositive power by reason of his retained right to substitute assets in such trust. According to the Issuers most recent Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, the number of shares outstanding as of October 31, 2025 was 53,829,982. The Ordinary Shares which the Reporting Person may be deemed to beneficially own constitute approximately 9.81% of such total number of shares 763,000 4,518,846 763,000 4,518,846 Y Y Y Y Y N By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11. SCULLY WILLIAM P Diana L. Hayes 11/12/2025 Pursuant to a Limited Power of Attorney dated as of February 13, 2024, a copy of which is on file with the Commission