Live Nation (NYSE:LYV) fell 8.5% in after hours trading amid reports that the Justice Department is preparing to file an antitrust lawsuit against the concert promoter as soon as next month.

The regulator is expected to allege that Live Nation (LYV) used its dominance in a matter that undermined competition for ticketing live events, according to a WSJ report on Monday, which cited people familiar with the matter. The specific charges the DOJ is expected to allege weren’t known.

Several state attorneys general are also involved in the probe and may decide to join the DOJ in its suit, according to a separate Bloomberg report on Monday.

“Ticketmaster has more competition today than it has ever had, and the deal terms with venues show it has nothing close to monopoly power,” a Ticketmaster spokeswoman told the WSJ.

A potential lawsuit comes after a Politico report in late July that the DOJ was preparing to file a lawsuit against Live Nation (LYV) by the end of last year.

A DOJ decree that forbade Live Nation from threatening venues with loss of access to tours was extended to 2025 after the Justice Dept. found repeated violations of that provision from 2010-2019.