ALKS: Leadership change · Company disclosure

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On September 14, 2026, the board of directors (the “Board”) of Alkermes plc (the “Company”) increased the size of the Board from ten (10) to eleven (11) directors and appointed Anne C. Whitaker to the Board, effective immediately, with an initial term expiring at the Company’s 2027 annual general meeting of shareholders. As of the date of this Current Report on Form 8-K, Ms. Whitaker has not been appointed to any committee of the Board. For her service on the Board, Ms. Whitaker will be entitled to receive an annual cash retainer and annual equity grant, both of which will be on the terms, and in the amounts, as determined in accordance with the processes described in the “Director Compensation” section of the Company’s definitive proxy statement filed with the Securities and Exchange Commission (the “SEC”) on April 6, 2026. In addition, in connection with her appointment to the Board, Ms. Whitaker will be granted an initial new director equity award with an aggregate target value of $600,000, consisting of 50% stock options and 50% restricted stock unit awards, which will vest and, as applicable, become exercisable in three equal annual installments commencing on the first anniversary of the grant date, subject to Ms. Whitaker’s continuous service. The new director equity award is expected to be granted to Ms. Whitaker in October 2026, on the Company’s monthly new hire employee grant date. The exercise price per share of the stock options will be equal to the closing price of the Company’s ordinary shares on the date of grant, as reported on the Nasdaq Global Select Market. In addition, the Company has entered into