X0508 4 2026-02-05 0001520262 Alkermes plc. ALKS 0001813312 Nichols Christian Todd 900 WINTER ST. WALTHAM MA 02451 1 SVP, Chief Commercial Officer 0 Ordinary Shares 2026-02-05 4 A 0 21127 A 107335 D Ordinary Shares 2026-02-05 4 F 0 6389 33.55 D 100946 D These ordinary shares were acquired by the reporting person as a result of the vesting of performance-vesting restricted stock unit awards granted to the reporting person on February 23, 2023 with a three-year performance period that ended on December 31, 2025 (the "2023 PRSUs"). The vesting of this portion of the 2023 PRSUs was triggered by the determination of achievement of certain pre-specified performance goals and application of a relative total shareholder return modifier and represents the final vesting event under the 2023 PRSUs. /s/ Shantale Greenson, attorney-in-fact for Christian Todd Nichols 2026-02-06