Alkermes plc

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. )

Registered in Ireland—No. 498284

Connaught House

1 Burlington Road

Dublin 4, Ireland, D04 C5Y6

NOTICE OF 2025 ANNUAL GENERAL MEETING OF SHAREHOLDERS SCHEDULEDTo be held MAY 21, 2025

To the Shareholders of Alkermes plc:

The 2025 Annual General Meeting of Shareholders (including any adjournments or postponements thereof, the “Annual Meeting”) of Alkermes plc (the “Company” or “Alkermes”), a company incorporated under the laws of Ireland, is scheduled to be held on May 21, 2025 at 1:00 p.m., Irish Standard Time, at the Company’s offices at Connaught House, 1 Burlington Road, Dublin 4, Ireland, D04 C5Y6, for the following purposes:

To elect, by separate resolutions, each of the following director nominees to serve on the Company’s Board of Directors (the “Board”) for a one-year term until the Company’s 2026 annual general meeting of shareholders:

To approve, in a non-binding, advisory vote, the compensation of the Company’s named executive officers.

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.

To approve the Alkermes plc 2018 Stock Option and Incentive Plan, as amended.

To renew Board authority to allot and issue shares under Irish law.

To renew Board authority to disapply the statutory pre-emption rights that would otherwise apply under Irish law.

To transact such other business as may properly come before the Annual Meeting.

Proposal 1 relates solely to the election of directors nominated by the Board and does not include any other matters relating to the election of directors. A separate resolution will be presented at the Annual Meeting for each of the director nominees. Proposals 2 through 5 are ordinary resolutions under Irish law, requiring the affirmative vote of a majority of the votes cast (in person or by proxy) on each resolution at the Annual Meeting for approval. Proposal 6 is a special resolution under Irish law, requiring the affirmative vote of the holders of at least 75% of the votes cast (in person or by proxy) at the Annual Meeting for approval. The foregoing items of business are more fully described in the proxy statement accompanying this notice. Shareholders as of March 14, 2025, the record date for the Annual Meeting, are entitled to notice of and to vote at the Annual Meeting.

ALKERMES PLC Notice of 2025 Annual Meeting

During the Annual Meeting, following a review of the Company’s affairs, management will present the Company’s Irish statutory financial statements for the year ended December 31, 2024, and the reports of the directors and the independent auditor and accounting firm thereon. There is no requirement under Irish law that the Irish statutory financial statements be approved by shareholders, and no such approval will be sought at the Annual Meeting.

YOUR VOTE IS VERY IMPORTANT. It is important that your voice be heard and your shares be represented at the Annual Meeting whether or not you are able to attend. We encourage you to cast your vote promptly so that your shares will be represented and voted at the meeting. 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. Your appointed proxy must attend the Annual Meeting in person in order for your votes to be cast. We recommend that you review the further information on the process for, and deadlines applicable to, voting and appointing a proxy under the section entitled “General Information about the Meeting and Voting” commencing on page 15 of the proxy statement accompanying this notice.

By Order of the Board of Directors.

DAVID J. GAFFIN

Secretary

Dublin, Ireland

April 7, 2025

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF SHAREHOLDERS TO BE HELD ON MAY 21, 2025. This notice, the accompanying proxy statement and the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 (together, the “Proxy Materials”) are available at www.proxydocs.com/ALKS. The Proxy Materials are also available free of charge on the Investors section of our website at www.alkermes.com.

The Company’s Irish statutory financial statements for the year ended December 31, 2024, including the related reports thereon (together, the “Irish Statutory Reports”), are available on the Annual Reports page of the Investors section of our website at www.alkermes.com.

Shareholders may obtain printed copies of the Proxy Materials and the Irish Statutory Reports free of charge by writing to our Company Secretary at Alkermes plc, Connaught House, 1 Burlington Road, Dublin 4, Ireland, D04 C576, Attention: Company Secretary.

ALKERMES PLC Notice of 2025 Annual Meeting

Letter to our Shareholders

Dear Fellow Shareholders,

2024 was a year of significant progress for Alkermes, marked by commercial execution, efficiency and profitability, and advancement and expansion of our pipeline.

We generated revenues of greater than $1.5 billion, driven primarily by our proprietary commercial portfolio of medicines that we discovered, developed, and commercialized. We completed the sale of our manufacturing business in Ireland, streamlining our manufacturing footprint and positioning the company to expand gross margins going forward. We drove robust profitability, yielding more than $450 million of EBITDA from continuing operations.

We used the profits we generated to strengthen our balance sheet and invest in the pipeline programs that we believe will drive the future growth of the company. We repurchased approximately 8 million of our ordinary shares, retired all of our debt, and ended the year with approximately $825 million of cash. We significantly advanced our neuroscience development pipeline, including ALKS 2680, our lead candidate being evaluated in narcolepsy and idiopathic hypersomnia, and our preclinical orexin agonist portfolio.

We also delivered strong total shareholder returns through December 31, 2024.

Underpinning these accomplishments is our continued operation of the business in an ethical and responsible manner. In 2024, we published our seventh annual Corporate Responsibility Report, highlighting our key environmental performance data, site-specific conservation and sustainability efforts, employee engagement, wellness and career development programs, community engagement and other employee-related initiatives.

We continued to engage regularly with shareholders throughout the year on topics of importance to the business. In 2024, as in prior years, our management team and Board had productive interactions with many of our shareholders. We thank these shareholders for their time and feedback and look forward to continued shareholder engagement in the future.

We have entered 2025 well-positioned to execute on our strategy, with a strong balance sheet, a substantial commercial business and a commitment to continued operational efficiency and profitability, while continuing to invest in the growth opportunities that we believe will be the key drivers of shareholder value.

Thank you for your continued support of Alkermes plc.

Sincerely,

ALKERMES PLC Letter to our Shareholders

Registered in Ireland—No. 498284

PROXY STATEMENT

2025 ANNUAL GENERAL MEETING OF SHAREHOLDERS SCHEDULED FOR MAY 21, 2025