Angelini Pharma agreed to buy Catalyst Pharmaceuticals for roughly $4.1 billion in cash, a move that positions the Italian company to scale its rare-disease footprint and gain a more direct foothold in the U.S. market. The deal values Catalyst at $31.50 per share, representing a 28% premium to the prior 30-day trading period before the transaction became public. Catalyst sells three approved rare-disease medicines and has built additional capabilities in neurology. For Angelini, the acquisition adds U.S. commercialization presence and expands its pipeline with approved products, potentially reducing time-to-impact versus adding only late-stage candidates. The market impact will likely depend on the combined revenue contribution of Catalyst’s current portfolio and Angelini’s ability to maintain growth while integrating a U.S.-focused commercial organization. Investors will also look for updates on how Angelini intends to develop Catalyst’s platform beyond the three approved medicines. No timeline for regulatory review or deal closing was included in the summary provided, but the transaction size suggests it will be closely watched for antitrust and cross-border approvals.