Company: PRTA
Filing Date: 2025-03-28
Form Type: DEF 14A
Source: 0001559053-25-000017
Chunk: 8

Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-03-28
Form: DEF 14A
Chunk 8
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 your vote is counted on all of the proposals.

If shareholders abstain from voting, including brokers holding their clients’ shares of record who cause abstentions to be recorded, these shares will be considered present and entitled to vote at the Annual Meeting and will be counted towards determining whether or not a quorum is present. Abstentions will not, however, be considered votes cast at the Annual Meeting.

Because the approval of each of the proposals is based on the votes cast at the Annual Meeting, abstentions and broker non-votes will not have any effect on the outcome of voting on any of the proposals.

| 2025 PROXY STATEMENT |     | 3 |

TABLE OF CONTENTS

| THE PROXY PROCESS AND SHAREHOLDER VOTING                     |
| QUESTIONS AND ANSWERS ABOUT THESE PROXY MATERIALS AND VOTING |

| 6. |     | How many votes do I have? |

On each matter to be voted upon, you have one vote for each ordinary share you own as of the Record Date.

| 7. |     | Why did I receive a notice in the mail regarding the internet availability of proxy materials instead of a full set of proxy materials? |

Pursuant to rules of the U.S. Securities and Exchange Commission (the “SEC”), Irish law, and our Constitution, we have elected to provide access to our proxy materials on the internet. Accordingly, we are sending a Notice of Internet Availability of Proxy Materials to our shareholders. All shareholders will have the ability to access the proxy materials on the website referred to in the Notice of Internet Availability of Proxy Materials or request to receive a printed set of the proxy materials. Instructions on

how to access the proxy materials on the internet or to request a printed copy may be found in the Notice of Internet Availability of Proxy Materials. In addition, shareholders may request to receive proxy materials in printed form by mail or electronically by email on an ongoing basis. We encourage shareholders to take advantage of the availability of the proxy materials on the internet to help reduce the environmental impact of the Annual Meeting.

| 8. |     | How do I vote via internet or telephone? |

You may vote by proxy on the internet by following the instructions provided on the proxy card or in the Notice of Internet Availability of Proxy Materials. If you request printed copies of the proxy materials by mail, you may vote by proxy by calling the toll-free number found on the proxy card. Please be aware that if you vote on the internet, you may incur costs such as internet access