Verizon Communications Inc has urged U.S. regulators not to restrict how much it can buy in next years auction of wireless spectrum, saying such a limit would subsidize the smallest national carriers and their foreign owners. Federal Communications Commission Chairman Tom Wheeler recently proposed rules for the complex sale of valuable airwaves scheduled for mid-2015. The rules would reserve part of the spectrum in each market for wireless carriers that do not already have dominant blocks of low-frequency airwaves there. That would benefit the No. 3 and No. 4 carriers, Sprint Corp and T-Mobile US Inc, by limiting the two biggest carriers, Verizon and ATT Inc, which dominate the highly valued low-band spectrum.