X0306 4 2019-06-05 0 0001492426 Horizon Therapeutics Public Ltd Co HZNP 0001769107 Kent Jeff C/O HORIZON PHARMA PLC CONNAUGHT HOUSE, 1ST FL, 1 BURLINGTON RD DUBLIN L2 4 IRELAND 0 1 0 0 See remarks Ordinary Shares 2019-06-05 4 S 0 3620 24.6433 A 104330 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 23, 2019. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.61 to $24.68 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. Includes 2,370 ordinary shares of the Issuer acquired by the reporting person on May 31, 2019 pursuant to an employee stock purchase program. Title: SVP, Head of Medical Affairs & Outcomes Research. /s/ Miles W. McHugh, Attorney-in-Fact 2019-06-07