The Department of Justice (DOJ) is planning to sue Live Nation, one of the largest ticketing and live events companies in the country, on antitrust grounds, a regulatory source familiar with the DOJ’s plans told Axios.

Live Nation acquired Ticketmaster in 2010. The DOJ at the time didn’t sue to block the deal, but barred the company from pressuring concert venues to use its ticketing software through a legal order called a consent decree.

The Wall Street Journal, which broke the news of a possible lawsuit Monday, reported that the DOJ could file suit as soon as next month. A source familiar with the DOJ’s plans told Axios that the timing is unclear.