UnitedHealth Group (UNH) shares were down nearly 5% Wednesday afternoon following a report that the giant health insurance provider is under a federal investigation for potential antitrus꧒t violations.

The Wall Street Journal reported on Tuesday that U.S. Department of Justice investigators have been questioning healthcare industry representatives where UnitedHealth competes, including doctor groups, according to people familiar with the meetings. 

Officials reportedly have been asking about certain relationshiꦗps between the company’s UnitedHealthcare insurance division and its Optum health-services unit, which owns physician groups, alon🉐g with other assets. 

Apparently part of🍒 the focus has been on how UnitedHealth’s purchase𒉰s of doctors’ groups may have affected rivals. 

The Journal noted that neither UnitedHealth nor the Justice Department responded to requests for comment. The story first appeared in The Examiner News of upstate New York.

The Justice Department is already looking into UnitedHealth’s planned $3.3 billion acquisition of home-healthcare company Amedisys (AMED). Amedisys noted in a regulatory filing in August that the DOJ had made a second request for information about the deal.

UnitedHealth shares were down 4.9% to $489.05 as of about 2:00 p.m. ET Wednesday.