X0306 4 2019-10-28 0 0000897448 AMARIN CORP PLC\UK AMRN 0001199637 THERO JOHN F C/O AMARIN PHARMA, INC. 440 US HIGHWAY 22 BRIDGEWATER NJ 08807 1 1 0 0 President and CEO Ordinary Shares 2019-10-28 4 M 0 11601 2.50 A 3092285 D Stock Option (Right to Buy) 2.50 2019-10-28 4 M 0 11601 0.00 D 2025-07-06 Ordinary Shares 11601 363400 D The Ordinary Shares may be represented by American Depositary Shares, each of which currently represents one Ordinary Share. Please see the section titled "Remarks" below for additional information. The stock option granted to the Reporting Person is fully vested as of the date hereof. As of the date of this Form 4, the Reporting Person owns or holds the right to acquire an aggregate of 9,707,117 Ordinary Shares of the Issuer in the form of Ordinary Shares, stock options and RSUs granted under the Amarin Corporation plc 2002 Stock Option Plan and the Amarin Corporation plc 2011 Stock Incentive Plan, including but not limited to certain performance-based Restricted Stock Units that are earned only if product revenues reach pre-defined annual milestone levels, then vest only if the recipient remains with the company for an extended period of time. /s/ John F. Thero 2019-10-30