Clearwire is a provider of fourth generation, or 4G, wireless broadband services. It builds and operates next generation mobile broadband networks that provide high-speed mobile Internet and residential access services, as well as residential voice services, in communities throughout the country. Clearwire operates a mobile WiMAX network. To date, Clearwire has invested heavily in building and augmenting its networks. It has a history of operating losses, and it expects to have significant losses in the future. As of December 31, 2010, its accumulated deficit was approximately $900.5 million. In December 2010, it raised approximately $1.40 billion in a debt offering to provide it with necessary additional funding for its business, and, as of the end of the year, the total principal outstanding on its debt was approximately $4.31 billion. In 2010, it increased the number of people covered by its networks by over 72.4 million. As of December 31, 2010, its networks covered an estimated 117.1 million people in the United States and Europe. In the United States, its networks covered an estimated 114.2 million people in 88 markets, including an estimated 112.0 million people covered by its 4G mobile broadband network in 71 markets. Source: SEC Filings