Horizon Therapeutics stock plunges on report FTC is preparing to block Amgen deal

Horizon Therapeutics‘ stock price plunged more than 17% in premarket trading Tuesday after a report that the Federal Trade Commission is preparing to file a lawsuit to block the biotech company’s $27.8 billion sale to Amgen. 

The FTC could sue to block the acquisition as soon as Tuesday, Bloomberg reported, citing an unnamed source.

An Amgen spokesperson told CNBC the company isn’t aware of any decision made by the FTC. Representatives for Horizon Therapeutics did not immediately respond to a request for comment from CNBC. The FTC declined to comment.

The two drugmakers said in February that the FTC sent them a second request for information about the acquisition as part of the agency’s review of the deal. 

Thousand Oaks, California-based Amgen struck the deal to buy Horizon Therapeutics in early December and said it expected to complete the sale in the first half of this year. 

The move was a bid to strengthen Amgen’s drug portfolio as it prepares to face several patent expirations for key treatments over the next decade.

That includes a patent for a medicine that treats psoriasis, an autoimmune condition that causes inflammation of the skin.

Horizon, which is based in Ireland, would beef up Amgen’s drug offerings with treatments for rare, autoimmune and severe inflammatory diseases. 

Horizon carries two fast-growing drugs, including the thyroid eye disease treatment Tepezza and the gout medicine Krystexxa. 

Sen. Elizabeth Warren, D-Mass., in January expressed concern about the deal’s potential impact on competition in the drug market. 

The acquisition and another proposed merger in the biopharma industry — between Indivor and Opiant — could “cause further price increases on lifesaving drugs and prevent affordable alternatives from entering the market,” Warren wrote in a letter to FTC Chair Lina Khan and two commissioners at the agency.

She called on the FTC to “heavily scrutinize” the two deals.