(AP) - The two largest wireless carriers, Verizon Wireless and AT&T, have been trying to bolster their spectrum holdings, while the next largest, Sprint and T-Mobile, have been seeking to make alliances to compete better. Here's a look at the merger and acquisition activity in the telecommunications industry since last summer:
_ June 26, 2012: Verizon Wireless agrees to sell some airwave rights to T-Mobile and swap others.
_ Aug. 2: AT&T Inc. announces three deals aimed at boosting its spectrum holdings. They are with Comcast Corp., NextWave Wireless Inc. and Horizon Wi-Com.
_ Aug. 24: A consortium of cable companies sell their spectrum holdings to Verizon Wireless for $3.6 billion.
_ Oct. 3: T-Mobile USA's parent company, Deutsche Telekom AG of Germany, agrees to buy MetroPCS Communications Inc. and merge T-Mobile into it.
_ Oct. 11: Japan's Softbank Corp. agrees to pay $20.1 billion for 70 percent of Sprint Nextel Corp., providing a much-needed cash boost for the struggling carrier.
_ Nov. 11: Sprint Nextel Corp. agrees to buy some U.S. Cellular Corp. service areas in the Midwest for $480 million.
_ Dec. 13: Sprint agrees to buy out the minority shareholders of wireless network operator Clearwire Corp., of which it already owns a majority.
_ Jan. 22, 2013: AT&T agrees to buy remnants of the Alltel network for $780 million.
_ Jan. 25: Verizon Wireless agrees to sell some spectrum rights to AT&T for $1.9 billion and swap some others.
_ April 30: T-Mobile completes acquisition of MetroPCS and becomes T-Mobile US Inc. T-Mobile adds 9 million MetroPCS customers to its own 34 million. T-Mobile plans to shut down MetroPCS's network over two years, freeing up space on the airwaves to improve its own coverage and data speeds.
_ July 9: Sprint completes acquisition of Clearwire.
_ July 10: Softbank completes Sprint deal, now worth $21.6 billion for a 78 percent stake. It comes after Softbank boosts its offer and satellite TV operator Dish Network Corp. abandons its $25.5 billion bid to buy Sprint in its entirety. As part of the new ownership, Sprint Nextel is changing its name to Sprint Corp.
_ July 12: AT&T says it will acquire Leap Wireless, the service provider of pre-paid, contract-free plans under the Cricket brand, for about $1.19 billion in cash. The purchase gives the nation's second largest cellphone carrier a leg-up in serving customers who prefer not to have lengthy contracts. It also would give AT&T the right to using Leap's unused airwaves in expanding its existing network.
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