X0306 4 2021-07-28 0 0001492426 Horizon Therapeutics Public Ltd Co HZNP 0001641580 Beeler Brian K C/O HORIZON THERAPEUTICS PLC CONNAUGHT HOUSE, 1ST FL, 1 BURLINGTON RD DUBLIN L2 4 IRELAND 0 1 0 0 EVP, General Counsel Ordinary Shares 2021-07-28 4 A 0 5806 0.00 A 102532 D Ordinary Shares 2021-07-28 4 F 0 2573 102.50 D 99959 D Performance Restricted Stock Units (PSUs) 2021-07-28 4 A 0 11612 0.00 A Ordinary Shares 11612 11612 D On January 3, 2020, the reporting person was granted performance-based restricted stock units (PSUs) of the Issuer, which vest upon the satisfaction of certain performance criteria. On July 28, 2021, such performance criteria were met, and the PSUs vested as to the number of shares reported in Table I above. The remaining ordinary shares subject to the PSUs vest in equal annual installments on January 5, 2022 and January 5, 2023. Includes 1,049 ordinary shares of the Issuer acquired by the reporting person on June 1, 2021 pursuant to an employee stock purchase program. Each PSU represents a contingent right to receive one ordinary share of the Issuer. /s/ Miles W. McHugh, Attorney-in-Fact 2021-07-30