Company: PRTA
Filing Date: 2025-03-28
Form Type: DEF 14A
Source: 0001559053-25-000017
Chunk: 9

Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-03-28
Form: DEF 14A
Chunk 9
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 or telephone charges for which you will be responsible. The internet and telephone voting facilities for eligible shareholders of record will close at 11:59 p.m. Eastern Time on May 12, 2025. The giving of such a proxy by internet

or telephone will not affect your right to vote in person should you decide to attend the Annual Meeting.

The internet and telephone voting procedures are designed to authenticate shareholders’ identities, to allow shareholders to give their voting instructions and to confirm that shareholders’ instructions have been recorded properly. If you vote by internet or telephone, that vote authorizes your proxy in the same manner as if you signed, dated, and returned a written proxy card by mail.

| 9. |     | What if I return a proxy card but do not make specific choices? |

If we receive a signed and dated proxy card and the proxy card does not specify how your shares are to be voted, your shares will be voted as follows:

• FOR the election, by separate resolutions, of Ms. Cobb, Dr. Ekman, and Dr. Kinney, as directors, to hold office until no later than our annual general meeting of shareholders in 2028;

• FOR the ratification, in a non-binding vote, of the appointment of KPMG LLP as our independent registered public accounting firm for our fiscal year 2025 and authorization, in a binding vote, of our Board, acting through its Audit Committee, to approve the remuneration of that auditor;

• FOR the approval, in a non-binding advisory vote, of the compensation of our named executive officers; and

• FOR the approval of the amendment to our 2018 Long Term Incentive Plan to increase the number of ordinary shares available for issuance under that Plan by 2,000,000 ordinary shares.

If any other matter is properly presented at the Annual Meeting, your proxy (one of the individuals named on your proxy card) will vote your shares using his or her discretion.

| 4 |     | 2025 PROXY STATEMENT |

TABLE OF CONTENTS

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

| 10. |     | Who is paying for this proxy solicitation? |

We will pay for the entire cost of soliciting proxies. In addition to these mailed proxy materials, our directors, officers, and employees may also solicit proxies in person, by telephone, or by