X0306 4 2021-02-20 0001520262 Alkermes plc. ALKS 0001730048 Hopkinson Craig C. 852 WINTER ST. WALTHAM MA 02451 1 EVP R&D, Chief Medical Officer Ordinary Shares 2021-02-20 4 M 0 10095 0 A 27131 D Ordinary Shares 2021-02-20 4 F 0 3064 19.58 D 24067 D Ordinary Shares 2021-02-21 4 M 0 6875 0 A 30942 D Ordinary Shares 2021-02-21 4 F 0 2022 19.58 D 28920 D Restricted Stock Unit Award 0 2021-02-20 4 M 0 10095 0 D Ordinary Shares 10095 30287 D Restricted Stock Unit Award 0 2021-02-21 4 M 0 6875 0 D Ordinary Shares 6875 13750 D Shares subject to the restricted stock unit award vest in four equal annual installments, commencing on 2/20/2021. Shares subject to the restricted stock unit award vest in four equal annual installments, commencing on 2/21/2020. /s/ Shantale Greenson, attorney-in-fact for Craig C. Hopkinson 2021-02-23