The Department of Justice has asked Ticketmaster Entertainment Inc. and concert promoter Live Nation Inc. for more information about their proposed merger, the companies said Friday.

It is the second request from the DOJ, indicating that it is scrutinizing the deal closer than most. The companies said the request was expected, and that they're cooperating with the antitrust investigation.

Ticketmaster is the world's largest seller of tickets to concerts and shows, and Live Nation is the largest U.S. operator of concert venues, with more than 140. The companies have been expecting to complete the deal in the second half of the year.

Artists have expressed concern that a combination would lead to a near-monopoly on large-scale concerts. Ticketmaster has drawn criticism recently from Bruce Springsteen fans, who say the company redirected them to its resale sites to charge more than the face value of the tickets.

Ticketmaster chairman Barry Diller repeated his denial of that practice late Thursday. He also said the complaints that fans were shut out of Phish and Michael Jackson concerts were due to the tickets selling out in seconds.

"Oddly, the better we sell tickets, the more unpopular we become," Diller said. Live Nation last year ended a long-term contract to sell its concert tickets through Ticketmaster, and it launched its own ticketing service for its venues in January. That threatened to siphon off at least 15 percent of Ticketmaster's revenue and had set the two companies up for a head-to-head fight to win ticketing contracts.

Ticketmaster shares fell 24 cents, or 5.8 percent, to $3.85 in morning trading Friday while Live Nation shares lost 13 cents, or 4.5 percent, to $2.79.