Prothena (PRTA) S-8Registration of securities for employees

The information called for in Part I of Form S-8 is not being filed with or included in this Form S-8 (by incorporation by reference or otherwise) in accordance with the rules and regulations of the Securities and Exchange Commission (the “Commission”). This Registration Statement on Form S-8 is filed by Prothena Corporation plc (the “Registrant”) regarding the Prothena Corporation plc 2018 Long Term Incentive Plan, as amended (the “2018 Plan”), and the Prothena Corporation plc 2020 Employment Inducement Incentive Plan, as amended (together with the 2018 Plan, the “Plans”). Documents containing the information required by Part I of the Registration Statement will be sent or given to participants in the Plans as specified by Rule 428(b)(1) under the Securities Act of 1933, as amended (the “Securities Act”).

The information incorporated by reference herein is considered to be part of this Registration Statement, and later information filed with the Commission will update and supersede this information. The following documents filed by the Registrant with the Commission are incorporated herein by reference:

All documents that the Registrant subsequently files pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the filing of a post-effective amendment to the Registration Statement which indicates that all of the ordinary shares offered have been sold or which deregisters all of such shares then remaining unsold shall be deemed to be incorporated by reference in this Registration Statement and to be a part hereof from the date of the filing of such documents, except as to any portion of any future annual or quarterly report to shareholders or document or current report furnished under Items 2.02 or 7.01 of Form 8-K, and exhibits furnished on such form that relate to such items, that is not deemed filed under such provisions. For the purposes of this Registration Statement, any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.

Under no circumstances will any information filed under current Items 2.02 or 7.01 of Form 8-K be deemed incorporated herein by reference unless such Form 8-K expressly provides to the contrary.

Under Irish law, a company may not exempt or indemnify its directors from liability for negligence or a breach of duty. However, where a breach of duty has been established, directors may be statutorily exempted by an Irish court from personal liability for negligence or breach of duty if, among other things, the court determines that they have acted honestly and reasonably, and that they may fairly be excused as a result.

The Irish Companies Act 2014 (the “Companies Act”) permits a company to pay the costs or discharge the liability of a director or the secretary only where judgment is given in his/her favor in any civil or criminal action in respect of such costs or liability, or where an Irish court grants relief because the director or secretary acted honestly and reasonably and ought fairly to be excused. This restriction does not apply to executives who are not directors or the secretary. Any obligation of an Irish company that purports to indemnify a director or secretary of an Irish company over and above this will be void under Irish law, whether contained in its articles of association or any contract between the director or secretary and the company.

The Registrant’s Amended and Restated Memorandum and Articles of Association (the “Constitution”), which has been publicly filed with the Commission, provides, so far as is permitted under the Companies Act, that every director and the secretary shall be entitled to be indemnified by the Registrant against all costs, charges, losses, expenses and liabilities incurred by him or her in the execution and discharge of his or her duties or in relation thereto including any liability incurred by him or her in defending any proceedings, civil or criminal, which relate to anything done or omitted or alleged to have been done or omitted by him or her as an officer or employee of the Registrant and in which judgement is given in his or her favour (or the proceedings are otherwise disposed of without any finding or admission of any material breach of duty on his or her part) or in which he or she is acquitted or in connection with any application under any statute for relief from liability in respect of any such act or omission in which relief is granted to him or her by the court.

In addition, the Constitution provides that the Registrant shall indemnify any of its current or former executives (excluding any directors or secretary), or any person who is serving or has served at the Registrant’s request as a director, executive or trustee of another company, joint venture, trust or other enterprise (each, a “Covered Person”), against expenses, including attorney’s fees, judgements, fines and amounts paid in settlement actually and reasonably incurred by him or her in connection with any threatened, pending, or completed action, suit or proceeding, whether civil, criminal, administrative or investigative, to which he or she was, is, or is threatened to be made a party, by reason of the fact that he or she is or was a Covered Person.

The directors and officers of the Registrant are covered by insurance policies indemnifying against certain liabilities, including certain liabilities arising under the Securities Act, which might be incurred by them in such capacities and against which they may not be indemnified by us.

The Registrant has also entered into indemnification agreements with each of its directors and executive officers. These agreements, among other things, require the Registrant to indemnify an indemnitee to the fullest extent permitted by applicable law, including indemnification of expenses such as attorneys’ fees, judgments, fines and settlement amounts incurred by the indemnitee in any action or proceeding, arising out of the person’s services as a director or executive officer.