Company: PRTA
Filing Date: 2025-09-25
Form Type: PRE 14A
Source: 0001140361-25-036135
Chunk: 2

Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-09-25
Form: PRE 14A
Chunk 2
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. For the EGM, we have elected to use the internet as the primary means of providing our proxy materials to shareholders. Consequently, some shareholders may not receive paper copies of our proxy materials. We intend to send shareholders a Notice of Internet Availability of Proxy Materials with instructions for accessing the proxy materials and for voting via the internet. The Notice of Internet Availability of Proxy Materials will also provide the date, time, and location of the EGM; the matters to be acted upon at the meeting and the Board of Directors’ recommendation with regard to each matter; a toll-free number, an e-mail address, and a website where shareholders can request a paper or e-mail copy of our Proxy Statement and form of proxy card; information on how to access their proxy card; and information on how to attend the meeting and vote in person. You are cordially invited to attend the EGM, but whether or not you expect to attend in person, you are urged to complete, sign, and date your proxy card and return it by mail or follow the alternative voting procedures described in the Notice of Internet Availability of Proxy Materials or the proxy card.

| By Order of the Board of Directors      |
| Michael J. Malecek                      
 Chief Legal Officer & Company Secretary 
 Dublin, Ireland                         
 [  ], 2025                              |

TABLE OF CONTENTS

TABLE OF CONTENTS

|                                                                                                                        |     | Page |
| GENERAL INFORMATION                                                                                                    |     |    1 |
| THE PROXY PROCESS AND SHAREHOLDER VOTING - QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING                |     |    2 |
| PROPOSAL NO. 1 - APPROVAL OF A REDUCTION OF THE COMPANY’S CAPITAL TO FACILITATE THE CREATION OF DISTRIBUTABLE RESERVES |     |    6 |
| SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT                                                         |     |    8 |
| HOUSEHOLDING OF PROXY MATERIALS                                                                                        |     |   10 |

TABLE OF CONTENTS

| PROTHENA CORPORATION PLC |

Registered in Ireland - No. 518146 77 Sir John Rogerson’s Quay, Block C, Grand Canal Docklands, Dublin 2, D02 VK60, Ireland PROXY STATEMENT FOR THE EXTRAORDINARY GENERAL MEETING OF SHAREHOLDERS TO BE HELD ON NOVEMBER 19, 2025 GENERAL INFORMATION The Board of Directors of Prothena Corporation plc is soliciting your proxy to