The Department of Justice has filed a civil antitrust suit to block AT&T's proposed $39 billion takeover of T-Mobile USA on the grounds that the deal would "substantially lessen competition." The deal would combine the second and fourth largest carriers to create a new market leader in the United States, ahead of current leader Verizon Wireless. Bloomberg reports that AT&T was surprised by the lawsuit and intends to fight so that "the enormous benefits of this merger can be fully reviewed." The DOJ's statement can be found here and the complaint here.