Company: PRTA
Filing Date: 2025-09-25
Form Type: PRE 14A
Source: 0001140361-25-036135
Chunk: 8

Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-09-25
Form: PRE 14A
Chunk 8
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 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 FOR the approval of the reduction of the Company’s capital to facilitate the creation of distributable reserves. If any other matter is properly presented at the EGM, your proxy (one of the individuals named on your proxy card) will vote your shares using his or her discretion.

| 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 other means of communication. Directors, officers, and employees will not be paid any additional compensation for soliciting proxies. We may also reimburse brokerage firms, banks, and other agents for the cost of forwarding proxy materials to beneficial owners.

| 11. |     | What does it mean if I receive more than one set of materials? |

If you receive more than one set of materials, your shares are registered in more than one name or are registered in different accounts. In order to vote all the shares you own, you must either sign and return all of the proxy cards or follow the instructions for any alternative voting procedure on each of the proxy cards or Notice of Internet Availability of Proxy Materials you receive.

| 12. |     | Can I change my vote after submitting my proxy? |

Yes. You may revoke your proxy at any time before commencement of the EGM. If you are the record holder of your shares, you may revoke your proxy in any one of three ways:

| • | You may deliver a written notice that you are revoking your proxy to our Company Secretary at Prothena Corporation plc, 77 Sir John Rogerson’s Quay, Block C, |

Grand Canal Docklands, Dublin 2, D02 VK60, Ireland, which notice must be delivered no later than 11:59 p.m. Eastern Time on November 18, 2025.

| • | You may attend the EGM and either vote or revoke your proxy in person. Simply attending the EGM will not, by itself, revoke your proxy. |

If your shares are held by your broker, bank, or other agent, you must contact the broker, bank, or other agent and follow the instructions provided by them.

| 4 |     | 2025 PROXY STATEMENT