Warning that Verizon Communications’ proposed acquisition of spectrum from a consortium of cable companies would result in “excessive concentration” of scarce wireless spectrum assets, T-Mobile USA asked the FCC on Tuesday to deny the $3.9 billion transaction. T-Mobile, the fourth-largest wireless carrier in the U.S., was one of several parties that petitioned the FCC this week to block the proposed spectrum purchase that also involves a cross-marketing arrangement between Verizon and members of the “SpectrumCo” wireless venture. In December, Verizon offered SpectrumCo—whose current members include Comcast, Time Warner Cable, and Bright House Networks—$3.6 billion for wireless spectrum that covers 259 million U.S. residents. Separately, Verizon also agreed to pay $315 million for wireless spectrum held by Cox Communications, a former SpectrumCo member. A related crossmarketing agreement grants the cable companies the right to market Verizon wireless services and also enables Verizon to market cable services offered by the SpectrumCo members in addition to Verizon’s own FiOS IPTV service. In a petition to deny, T-Mobile charged that the plan would enable Verizon “to accumulate even more spectrum on top of an already dominant position. Similarly, a group of nine public interest groups consisting of Public Knowledge, the New America Foundation, and the Media Access Project urged the FCC to delay the deal. Sprint Nextel stopped short of recommending the deal’s blockage as it urged the FCC to examine closely the cross-marketing arrangement between the parties. Defending its spectrum purchase as one that serves the public interest, Verizon replied that the deal conforms to the FCC’s goal of ensuring “that existing spectrum is used by providers who can use it efficiently.”