X0306 4 2022-01-28 0 0001492426 Horizon Therapeutics Public Ltd Co HZNP 0001349376 Walbert Timothy P C/O HORIZON THERAPEUTICS PLC, 70 SAINT STEPHEN?S GREEN DUBLIN L2 D02 E2X4 IRELAND 1 1 0 0 Chairman, President and CEO Ordinary Shares 2022-01-28 4 M 0 25000 22.14 A 710549 D Ordinary Shares 2022-01-28 4 S 0 25000 90.00 D 685549 D Ordinary Shares 2022-01-31 4 S 0 14541 90.95 D 671008 D Ordinary Shares 2022-01-31 4 S 0 74253 91.94 D 596755 D Ordinary Shares 2022-01-31 4 S 0 11206 92.42 D 585549 D Ordinary Shares 107739 I See footnote Ordinary Shares 100300 I See footnote Ordinary Shares 35603 I By spouse Stock Option (Right to Buy) 22.14 2022-01-28 4 M 0 25000 0.00 D 2025-03-22 Ordinary Shares 25000 967565 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 1, 2021. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $90.32 to $91.305 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $91.34 to $92.335 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. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $92.34 to $92.62 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. The shares are held by the Timothy P. Walbert 2021 Gift Trust, of which the Reporting Person's spouse is the Trustee and beneficiary. The shares are held by the Keli B. Walbert 2021 Gift Trust, of which the Reporting Person is the Trustee. The beneficiaries of the Trust include the Reporting Person and his descendants. The stock option is fully vested and exercisable. /s/ Miles W. McHugh, Attorney-in-Fact 2022-01-31