The US Federal Trade Commission will sue to block Amgen’s $28.3bn deal to acquire Horizon Therapeutics, according to a person familiar with the matter.
The lawsuit, which is set to be filed on Tuesday, would mark the first time in more than a decade that the FTC has sought to block a deal in the pharmaceutical sector.
FTC chair Lina Khan is among a new cohort of progressive antitrust officials appointed by US president Joe Biden, who have vowed to adopt a tougher stance and crack down on anti-competitive conduct in the US.
Shares in Horizon, which is based in Ireland, were down more than 17 per cent in pre-market trade. The news also appeared to hit Seagen, which was down 5.6 per cent in pre-market trade as investors weighed the possibility of the FTC targeting other deals in the sector. The oncology-focused biotech agreed a $43bn deal in March to be acquired by Pfizer.
The move was first reported by Bloomberg.
Additional reporting by Peter Wells in New York