X0306 4 2018-03-01 0001520262 Alkermes plc. ALKS 0001235595 BIBERSTEIN KATHRYN L 852 WINTER ST. WALTHAM MA 02451 1 EVP/CAO/CCO/CRO Alks Inc; Ordinary Shares 2018-03-01 4 M 0 5750 0 A 40463 D Ordinary Shares 2018-03-01 4 F 0 2207 57.41 D 38256 D Ordinary Shares 2018-03-03 4 M 0 3500 0 A 41756 D Ordinary Shares 2018-03-03 4 F 0 1556 60.05 D 40200 D Ordinary Shares 28856 I By 2016 GRAT Ordinary Shares 113017 I By 2017 GRAT Restricted Stock Unit Award 0 2018-03-01 4 M 0 5750 0 D 2017-03-01 Ordinary Shares 5750 11500 D Restricted Stock Unit Award 0 2018-03-03 4 M 0 3500 0 D Ordinary Shares 3500 0 D Shares held by the Kathryn L. Biberstein 2016 Annuity Trust dated December 9, 2016 (the "2016 GRAT"). The Reporting Person is a trustee and beneficiary of the 2016 GRAT and may be deemed to hold voting and dispositive power with regard to the reported shares held by the 2016 GRAT. Shares held by the Kathryn L. Biberstein 2017 Annuity Trust dated December 11, 2017 (the "2017 GRAT"). The Reporting Person is a trustee and beneficiary of the 2017 GRAT and may be deemed to hold voting and dispositive power with regard to the reported shares held by the 2017 GRAT. Shares subject to the restricted stock unit award vest in equal annual installments over a four year period, commencing on 3/1/2017. This RSU award is fully vested in accordance with its terms. /s/ Jennifer Baptiste, attorney-in-fact for Kathryn L. Biberstein 2018-03-05