UPDATE, 4:04 PM: Activist group Public Knowledge is first out urging government officials to reject the AT&T-Leap deal. “Since the federal government said ‘no’ to AT&T’s efforts to take over T-Mobile in 2011, AT&T has been slowly buying up smaller companies and wireless licenses all over the country,” the group’s SVP Harold Feld says. Low income consumers would be hurt if AT&T eliminated Leap’s pre-paid wireless offering. “This is getting ridiculous. The Justice Department and the Federal Communications Commission need to say ‘no’ to this latest effort by AT&T to buy out its rivals and rebuild ‘Ma Cell.'”

PREVIOUS, 2:21 PM: Leap Wireless’ stock price is up nearly 110% in post market trading after AT&T said that it would pay $15 a share — an 88% premium over Friday’s $7.98 closing price — to buy the mobile provider, which has about 5M subscribers. In addition to the $1.2B in cash for the stock, AT&T will assume $2.8B in Leap’s debt, and give its shareholders a right to the proceeds from the sale of some spectrum in Chicago. AT&T says that it will keep Leap’s Cricket brand mobile service, which reaches 96M people in 35 states. In addition, the company will use Leap’s unutilized spectrum to help expand AT&T’s 4G wireless broadband service. Strangely, the companies’ release does not include any comments from executives. But it says that the deal will result in “increased competition, better device choices, improved customer care and a significantly enhanced mobile Internet experience for consumers seeking low-cost prepaid wireless plans.” Owners of 29.8% of Leap’s shares have agreed to vote for the deal with AT&T. That could put put a crimp in Dish Network’s plans: The satellite company has amassed wireless spectrum in the  hope of building a national broadband system, but Chairman Charlie Ergen has said that he probably needs a partner to make his dream a reality. Leap had been seen as a possible target after Dish failed in its attempt to buy Sprint, and a large stake in wireless broadband company Clearwire. The deal also comes as phone companies brace for a slowdown in smartphone sales. “We are nearing the end of a golden age,” MoffettResearch analyst Craig Moffett said this week. “New smartphone adoption has driven a once-in-a-lifetime cycle of higher [revenues per subscriber]…and higher asset utilization. From here, however, the next ‘big thing’ is much harder to identify than it has been in the past.”