Minnesota-based UnitedHealth Group Inc. is the focus of an antitrust lawsuit filed on Tuesday by the United States Department of Justice.

Amedisys (NASDAQ:AMED) fell 2% in premarket trading on a report that the Dept. of Justice has signed off on a lawsuit to challenge UnitedHealth's $3.3 billion purchase of the home-health services provider.

The merger would further consolidate UnitedHealth's standing as the dominant force in the American healthcare system, lawsuit says.

The U.S. Department of Justice (DOJ) recently filed a lawsuit to block UnitedHealth Group Incorporated’s UNH $3.3 billion acquisition of Amedisys, Inc. AMED, arguing that the merger would hurt competition in the home health and hospice care market.

The Justice Department is suing to block UnitedHealth Group’s $3.3 billion purchase of Amedisys, citing concerns the combination would hinder access to home health and hospice services in the U.S.

The U.S. Justice Department and four states sued Tuesday to block UnitedHealth Group’s proposed $3.3 billion acquisition of Amedisys, a Louisiana-based home health company that would further United’s push into the home care and hospice markets.