X0306 4 2018-12-07 0001520262 Alkermes plc. ALKS 0001235598 FRATES JAMES M CONNAUGHT HOUSE 1 BURLINGTON ROAD DUBLIN 4 Ireland 1 SVP, Alks Inc; CFO ALKS Ordinary Shares 2018-12-07 4 A 0 5500 0 A 42734 D Ordinary Shares 2018-12-07 4 F 0 2445 34.01 D 40289 D Ordinary Shares 4000 I By Sons Ordinary Shares 17204 I By 2014 GRAT Ordinary Shares 80000 I By 2018 GRAT No. 1 Ordinary Shares 45000 I By 2018 GRAT No. 2 These shares were acquired by the reporting person as a result of the partial vesting of performance-vesting restricted stock units granted to the reporting person on February 17, 2017. The vesting of this portion of the performance-vesting restricted stock units was triggered by ALKS 3831 achieving the pre-specified primary efficacy endpoints in each of two phase 3 studies. Shares held by James M. Frates Grantor Retained Annuity Trust dated March 14, 2014 (the "2014 GRAT"). The Reporting Person is a trustee and beneficiary of the 2014 GRAT and may be deemed to hold voting and dispositive power with regard to the reported shares held by the 2014 GRAT. Shares held by the James M. Frates 2018 Grantor Retained Annuity Trust No. 1 dated February 22, 2018 (the "2018 GRAT No. 1"). The Reporting Person is a trustee and beneficiary of the 2018 GRAT No. 1 and may be deemed to hold voting and dispositive power with regard to the reported shares held by the 2018 GRAT No. 1. Shares held by the 2018 GRAT No. 2. The Reporting Person is a trustee and beneficiary of the 2018 GRAT No. 2 and may be deemed to hold voting and dispositive power with regard to the reported shares held by the 2018 GRAT No. 2. /s/ Jennifer Baptiste, attorney-in-fact for James M. Frates 2018-12-11