The U.S. Department of Justice (DOJ) has filed an antitrust lawsuit to block the acquisition of Amedisys (Nasdaq: AMED) by the UnitedHealth Group (NYSE: UNH) subsidiary Optum.

Bloomberg first reported the news. This comes on heels of a “last rights” meeting between the DOJ and the two companies to advocate for sealing the deal. Amedisys stock dropped 4% on Monday as rumors of a pending lawsuit circulated. The case will be heard in a federal court in Maryland, with the attorneys general of Maryland, New York, Illinois and New Jersey also joining the complaint.

“The primary basis of the DOJ suit purportedly concerns the combination leading to higher home health care prices in the regions where AMED is a main competitor of UNH’s LHCG, which the company acquired in 2023,” Scott Fidel, analyst for Stephens, indicated in a research note. “To relieve these concerns, AMED proposed the disposition of 100+ locations to a private operator in [Texas] contingent on deal close. However, these remedies do not seem sufficient to satisfy the hardline Biden DOJ.”

Optum, in June 2023 penned its agreement to acquire Amedisys in an all-cash transaction of $101 per share, or about $3.3 billion. The transaction is expected to close this year.

Last summer, DOJ began investigating potential antitrust concerns related to the Amedisys-Optum deal. To date, neither Amedisys nor Optum have been accused of any wrongdoing.

The DOJ performed a similar investigation — and filed a lawsuit — when Optum acquired the health care technology company Change Healthcare. A federal court eventually allowed that deal to proceed.

In order to mitigate antitrust concerns, Amedisys has agreed to sell some of its locations to the PE-backed home health and hospice provider VitalCaring, possibly more than 100. The VitalCaring transaction is contingent on approval of the UnitedHealth Group acquisition.

DOJ’s attention to the transaction reflects a larger federal focus on antitrust actions. President Joe Biden signed an executive order that created a White House Competition Council shortly after taking office. The order was designed to address antitrust concerns in a range of industries, including health care.