144 0001645326 XXXXXXXX LIVE 0001297184 Amphastar Pharmaceuticals, Inc. 001-36509 11570 SIXTH STREET RANCHO CUCAMONGA CA 91730 909-980-9484 Rong Zhou Officer Common Stock UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

20000 500000 45950000 11/28/2025 NASDAQ Common Stock 11/28/2025 Stock Option Exercising Issuer N 20000 11/28/2025 N/A Y 11/28/2025 /s/JOSEPH CASSIDY, for UBS Financial Services Inc, as attorney-in-fact for Rong Zhou