Company: PRTA
Filing Date: 2025-10-07
Form Type: DEF 14A
Source: 0001140361-25-037500
Chunk: 13

Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-10-07
Form: DEF 14A
Chunk 13
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 THE COMPANY'S CAPITAL TO             
 CREATE DISTRIBUTABLE RESERVES.                                       |

| 2025 PROXY STATEMENT FOR EXTRAORDINARY GENERAL MEETING |     | 7 |

TABLE OF CONTENTS

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT The following table presents information as to the beneficial ownership of our ordinary shares as of September 24, 2025, (except as noted) for:

| • | each person, or group of affiliated persons, known by us to beneficially own more than 5% of our ordinary shares; |

| • | each of our directors; |

| • | each of our executive officers named in theSummary Compensation Table - Fiscal Year 2024; and |

| • | all of our directors and executive officers as a group. |

Unless otherwise indicated, the address of each beneficial owner named below is c/o Prothena Corporation plc, 77 Sir John Rogerson’s Quay, Block C, Grand Canal Docklands, Dublin 2, D02 VK60, Ireland.

| Name of Beneficial Owner                         |     | Amount and Nature of Beneficial Ownership(1) |     |                   |     |              |     |             |
| 5% Shareholders:                                 |     |                                       Shares |     | Shares            
 Acquirable        
 Within 60 Days(2) |     | Total Shares 
       Deemed 
 Beneficially 
        Owned |     | Percent of  
 Outstanding 
 Shares(3)   |
| Entities Associated with Fidelity Investments(4) |     |                                    8,049,796 |     | —                 |     |    8,049,796 |     | 15.0%       |
| William P. Scully(5)                             |     |                                    5,351,846 |     | —                 |     |    5,351,846 |     | 9.9%        |
| Todd W. Fennell(6)                               |     |                                    4,350,846 |     | —                 |     |    4,350,846 |     | 8.1%        |
| BlackRock, Inc.(7)                               |     |                                    3,770,650 |     | —                 |     |    3,770,650 |     | 7.0%        |
| ADAR1 Capital Management, LLC(8)                 |     |                                    3,375,009 |     | —