X0306 4 2017-07-03 0001520262 Alkermes plc. ALKS 0001236454 MITCHELL PAUL J CONNAUGHT HOUSE 1 BURLINGTON ROAD DUBLIN 4 IRELAND 1 Ordinary Shares 2017-07-03 4 M 0 1500 11.44 A 9500 D Ordinary Shares 2017-07-03 4 S 0 1500 58.11 D 8000 D Non Qualified Stock Option (Right to Buy) 11.44 2017-07-03 4 M 0 1500 0 D 2018-10-07 Ordinary Shares 1500 9500 D This option exercise was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 9/13/16. This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on 9/13/16. These options are fully vested in accordance with their terms. /s/ Jennifer Baptiste, attorney-in-fact for Paul J. Mitchell 2017-07-06