Alkermes plc. — Director's Dealing 2012

May 18, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Alkermes plc. (ALKS)
CIK: 0001520262
Period of Report: 2012-05-17

Reporting Person: FRATES JAMES M (SVP & CFO, Alkermes plc)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-05-17	Ordinary Shares	M	4350	—	Acquired	83975	Direct
2012-05-17	Ordinary Shares	F	1379	$16.71	Disposed	82596	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-05-17	Restricted Stock Unit Award	$0	M	4350	Disposed		Ordinary Shares (4350)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Ordinary Shares	4000	Indirect

Footnotes

F1: Shares subject to the restricted stock unit award vest in equal annual installments over a four year period, commencing on 5/17/11.