X0306 4 2019-02-25 0 0001492426 Horizon Pharma plc HZNP 0001667903 CURTIS GEOFFREY M. C/O HORIZON PHARMA PLC CONNAUGHT HOUSE, 1ST FL, 1 BURLINGTON RD DUBLIN L2 4 IRELAND 0 1 0 0 EVP, Corporate Affairs, CCO Ordinary Shares 2019-02-25 4 S 0 3580 21.20 D 35367 D Ordinary Shares 2019-02-25 4 S 0 4500 21.19 D 30867 D Ordinary Shares 2019-02-25 4 S 0 2000 21.26 D 28867 D Ordinary Shares 420 I By spouse The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 13, 2018. /s/ Miles W. McHugh, Attorney-in-Fact 2019-02-25