Behind Verizon is AT&T, which has 125 markets covered with its 4G LTE signal. In addition, AT&T still offers HSPA+ in a number of markets making the mobile operator the largest 4G provider in the U.S. Sprint, which just started rolling out LTE this June, is already up to 49 markets. The last of the major carriers, T-Mobile, will acquire some LTE covered territory when it closes on its purchase of pre-paid operator MetroPCS. Additionally, T-Mobile is planning to begin building its LTE pipeline starting in 2013.
source: Verizon via AndroidGuys