Additional Proxy Soliciting Materials (Form DEFA14A)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No. )

C/O BETANXT, INC. P.O. BOX 8016, CARY, NC 27512-9903 Your vote Alkermes plc 2026 Annual General Meeting of Shareholders Wednesday, May 20, 2026, 2:00 PM, Irish Standard Time Alkermes plc offices, located at Connaught House, 1 Burlington Road, Dublin 4, Ireland, D04 C5Y6 Meeting Materials: Notice of Meeting and Proxy Statement; Annual Report on Form 10-K Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Shareholders to be held on May 20, 2026 for Shareholders as of March 13, 2026 To request paper materials, please use one of the following methods: For a convenient way to view Alkermes plc's proxy materials, and VOTE your shares, please visit www.proxydocs.com/ALKS. To vote while visiting this site, you will need the 12 digit control number in the box below. You may vote your proxy by Internet or telephone prior to 11:59 PM Eastern Standard Time on May 19, 2026 (4:59 AM Irish Standard Time on May 20, 2026). This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. This is not a ballot. You cannot use this Notice to vote your shares. We encourage you to access and review all of the important information contained in the proxy materials before voting. Under U.S. Securities and Exchange Commission rules, proxy materials do not have to be delivered in paper copy. Proxy materials can be distributed by making them available on the Internet. If you want to receive a paper or e-mail copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. In order to receive a paper copy in time for the Alkermes plc (the "Company") 2026 annual general meeting of shareholders (the "Annual Meeting"), you must make this request on or before May 8, 2026. SEE REVERSE FOR PROXY PROPOSALS Internet: www.investorelections.com/ALKS Call: 1-866-648-8133 Email: [email protected] * If requesting receipt of proxy materials, please send a blank e-mail with the 12 digit control number (located below) in the subject line. No other requests, instructions or other inquiries should be included with your e-mail requesting proxy materials. Have the 12 digit control number located in the box above available when you access the website and follow the instructions. Copyright 2026 BetaNXT, Inc. or its affiliates. All Rights Reserved

Alkermes plc 2026 Annual General Meeting of Shareholders THE BOARD OF DIRECTORS OF THE COMPANY (THE "BOARD") RECOMMENDS A VOTE: FOR ALL DIRECTOR NOMINEES NAMED IN PROPOSAL 1 FOR PROPOSALS 2, 3, 4, 5 AND 6 PROPOSAL 1. To elect as directors to serve a one-year term until the Company's 2027 annual general meeting of shareholders: 1.01 Shane M. Cooke 1.02 Richard B. Gaynor, M.D. 1.03 Cato T. Laurencin, M.D., Ph.D. 1.04 Nancy S. Lurker 1.05 Brian P. McKeon 1.06 Richard F. Pops 1.07 Nancy L. Snyderman, M.D. 1.08 Frank Anders Wilson 1.09 Christopher I. Wright, M.D., Ph.D. 2. To approve, in a non-binding, advisory vote, the compensation of the Company's named executive officers. 3. To ratify, in a non-binding vote, the appointment of PricewaterhouseCoopers LLP as the independent auditor and accounting firm of the Company and to authorize, in a binding vote, the Audit and Risk Committee of the Board to set the independent auditor and accounting firm's remuneration. 4. To approve the Alkermes plc 2018 Stock Option and Incentive Plan, as amended. 5. To renew Board authority to allot and issue shares under Irish law. 6. To renew Board authority to disapply the statutory pre-emption rights that would otherwise apply under Irish law. If any other matter is presented at the Annual Meeting upon which a vote may be properly taken, ordinary shares represented by all proxy cards received by the Company will be voted at the discretion of the named proxy holders as set forth on the proxy card. Any shareholder entitled to attend, speak and vote at the Annual Meeting may appoint one or more proxies, who need not be a shareholder of record of the Company. If you wish to appoint as proxy any person other than the individuals specified on the Company's proxy card, you may do so by contacting the Company Secretary at Alkermes plc, Connaught House, 1 Burlington Road, Dublin 4, Ireland, D04 C5Y6, Attention: Company Secretary, or by delivering to the Company Secretary a proxy card in the form mailed to you or in the form set forth in Section 184 of the Irish Companies Act 2014. To obtain directions to attend the Annual Meeting, please contact the Company's Investor Relations team at [email protected]. The Company's Irish statutory financial statements for the year ended December 31, 2025, including the reports of the directors and auditors thereon, are available on the Annual Reports page of the Investors section of the Company s website at http://investor.alkermes.com. If you wish to receive a paper or e-mail copy, please contact the Company Secretary using the contact information above.