The U.S. Federal Trade Commission is suing Live Nation and its ticketing arm Ticketmaster for tacitly allowing ticket brokers to violate its policies and scoop up millions of concert tickets later sold to fans at a significant markup, the agency said Thursday.

Ticketmaster, which controls 80% of primary ticketing for major concert venues, ignored brokers' violations of ticket purchasing limits set by artists in order to generate profit off the brokers' resales to fans, the FTC alleged. The actions violated consumer protection law, the agency said.

Live Nation shares were trading down 2.3% on the news.