Alkermes plc. — Director's Dealing 2015

May 22, 2015

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Alkermes plc. (ALKS)
CIK: 0001520262
Period of Report: 2015-05-20

Reporting Person: Peterson Rebecca (SVP, Corporate Communications)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2015-05-20	Ordinary Shares	M	8750	$18.105	Acquired	8750	Direct
2015-05-20	Ordinary Shares	S	7700	$61.8354	Disposed	1050	Direct
2015-05-20	Ordinary Shares	S	1050	$62.5033	Disposed	0	Direct
2015-05-20	Ordinary Shares	M	2000	—	Acquired	2000	Direct
2015-05-20	Ordinary Shares	F	942	$62.10	Disposed	1058	Direct
2015-05-21	Ordinary Shares	M	18750	$16.55	Acquired	19808	Direct
2015-05-21	Ordinary Shares	S	16150	$61.531	Disposed	3658	Direct
2015-05-21	Ordinary Shares	S	2600	$62.4259	Disposed	1058	Direct
2015-05-22	Ordinary Shares	S	1058	$61.11	Disposed	0	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2015-05-20	Employee Stock Option (Right to Buy)	$18.105	M	8750	Disposed	2021-05-20	Ordinary Shares (8750)	Direct
2015-05-20	Restricted Stock Unit Award	$0	M	2000	Disposed		Ordinary Shares (2000)	Direct
2015-05-21	Employee Stock Option (Right to Buy)	$16.55	M	18750	Disposed	2022-05-21	Ordinary Shares (18750)	Direct

Footnotes

F1: This option exercise was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F2: This sale was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person.

F3: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $61.36 to $62.32. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

F4: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $62.40 to $62.58. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

F5: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $61.12 to $62.10. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

F6: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $62.13 to $62.95. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

F7: These options are fully vested in accordance with their terms.

F8: This RSU award is fully vested in accordance with its terms.

F9: Shares subject to the stock option award vest in four equal annual installments commencing on 5/21/13.