Alkermes plc

Trading Plans

During the quarter ended December 31, 2023, the following officers (as defined in Rule 16a-1(f) under the Exchange Act) of the Company adopted contracts, instructions or written plans for the purchase or sale of the Company’s securities that were intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act (each, a “Rule 10b5-1 plan”): On December 14, 2023, Craig Hopkinson, M.D., our Executive Vice President, Research and Development and Chief Medical Officer, adopted a Rule 10b5-1 plan providing for the sale of up to 820,467 ordinary shares of the Company (including shares that may be obtained from the exercise of vested stock options or vesting of restricted stock unit awards); this plan is scheduled to expire on July 31, 2025. On December 14, 2023, Christian Todd Nichols, our Senior Vice President Chief Commercial Officer, adopted a Rule 10b5-1 plan providing for the sale of up to 10,417 ordinary shares of the Company; this plan is scheduled to expire on August 2, 2024. During the quarter ended December 31, 2023, no other officers or directors of the Company adopted, modified orterminated a Rule 10b5-1 plan or a trading plan not intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act.