The purchase gives the nation's No. 2 cellphone carrier a leg-up in serving customers who prefer not to have lengthy contracts. Leap's Cricket service has 5 million subscribers who pay monthly without a contract. The deal also gives AT&T the right to use Leap's unused airwaves—also known as spectrum—to expand its network.
Spectrum is the lifeblood of the wireless industry and the fight to grab more of it has spurred a recent wave of consolidation.
In April, No. 4 T-Mobile completed its acquisition of pre-paid carrier MetroPCS. The company plans to shut down the MetroPCS network in two years, so it can use the airwaves to improve coverage and data speeds. On Wednesday, Japan's SoftBank Corp. completed its $21.6 billion takeover of No. 3 Sprint Corp, which helped Sprint acquire Clearwire Corp. and its spectrum holdings a day earlier.
Charles Golvin, a technology analyst with research firm Forrester, said Leap's spectrum holdings will allow AT&T to offer more of its customers faster, more reliable wireless data in congested areas.
"Having more spectrum means having more capacity and being able to meet those long-term data demands," Golvin said.
As part of its deal, AT&T plans to keep the Cricket brand name, but provide Cricket customers with a broader range of devices and give them access to AT&T's "4G LTE" high-speed wireless network. AT&T says it plans to expand Cricket's presence in the U.S.
As of March, AT&T had 7.1 million pre-paid customers through its GoPhone and Aio brands. AT&T has 107 million wireless customers in total.
"The pre-paid market for us is relatively untapped," said AT&T spokesman Brad Burns. "From a competition perspective, this creates a much healthier competitor in the pre-paid space."
AT&T will buy all of Leap's stock and wireless properties, including licenses, network and retail stores. Leap's unused spectrum covers portions of the country that include 41 million people.
The companies said owners of nearly 30 percent of Leap shares have agreed to vote in favor of the deal.
Leap shares skyrocketed in after-hours trading on the news, more than doubling to $17.31, well past the offer price. The stock's movement suggests the market believes a higher bid will emerge. AT&T shares slipped a penny to $35.80.
Leap, based in San Diego, had $2.8 billion of debt.
The nation's sixth-ranked carrier had been struggling. In the quarter through March, Leap's net loss expanded to $110 million as it lost a net 93,000 wireless customers. Its revenue in the same period declined 12 percent from a year ago to $685 million.
"Senior management looked at (the acquisition by AT&T) as our best path forward for the company's long-term success," Leap spokesman Greg Lund said.
Cricket is considered a regional carrier. Its network covers regions of the country housing 96 million people in 35 states. It also provides national coverage through a roaming agreement with Sprint, which won't be needed if its tie-up with AT&T gains regulatory approval.
Cricket phones are also sold outside its own coverage area in the U.S. through Radio Shack and Walmart stores.
AT&T said it expects the deal will close in six to nine months, although it requires approval from the Federal Communications Commission and Department of Justice.
Federal regulators have been averse to permitting larger carriers to merge.
In late 2011, AT&T abandoned its $39 billion bid to buy T-Mobile after the Justice Department raised its objection to the deal on the grounds it would raise prices and give customers fewer choices.
Free Press, a media and technology watchdog organization in Washington, registered its opposition to this latest deal.
"This is (a) smaller deal, but AT&T is sure to make the same false claims it tried with T-Mobile," Free Press CEO Craig Aaron said in a statement. "This takeover would result in fewer choices, higher prices and job losses."