144 0001611286 XXXXXXXX LIVE 0001297184 Amphastar Pharmaceuticals, Inc. 001-36509 11570 SIXTH STREET RANCHO CUCAMONGA CA 91730 909-980-9484 Floyd Petersen Director Common Stock UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

1737 43425 45950000 12/10/2025 NASDAQ Common Stock 06/07/2022 RSU Vesting Issuer N 1737 06/07/2022 N/A N Floyd Petersen

11570 SIXTH STREET RANCHO CUCAMONGA CA 91730

Common Stock 11/13/2025 16679 411811 Floyd Petersen

11570 SIXTH STREET RANCHO CUCAMONGA CA 91730

Common Stock 11/03/2025 500 12612 Floyd Petersen

11570 SIXTH STREET RANCHO CUCAMONGA CA 91730

Common Stock 10/01/2025 500 13582 12/10/2025 /s/Mijo Suric, for UBS Financial Services Inc, as attorney-in-fact for Floyd Petersen