Antitrust developments in the health care and pharmaceutical industries were exceptionally active in 2023. From the Federal Trade Commission's (FTC) challenge of a merger between Amgen Inc. (Amgen) and Horizon Therapeutics plc (Horizon), to joint agency withdrawal of well-established health care merger policy statements, to agency interest in pharmacy benefit managers (PBMs), we review some of the most notable antitrust activity in the health care and pharmaceutical industries over the past year.