Sirius XM Radio Inc. has two principal wholly owned subsidiaries, XM Satellite Radio Holdings Inc. and Satellite CD Radio Inc. The Company is engaged in broadcasting in the United States, its music, sports, news, talk, entertainment, traffic and weather channels for a subscription fee through its satellite radio systems, the SIRIUS system and the XM system. On July 28, 2008, its wholly owned subsidiary, Vernon Merger Corporation, merged (the Merger) with and into XM Satellite Radio Holdings Inc. and, as a result, XM Satellite Radio Holdings Inc. became its wholly owned subsidiary. The SIRIUS system consists of three in-orbit satellites, approximately 120 terrestrial repeaters that receive and retransmit signals, satellite uplink facilities and studios. The XM system consists of four in-orbit satellites, over 700 terrestrial repeaters that receive and retransmit signals, satellite uplink facilities and studios.