Microsoft's portfolio of mergers and acquisitions includes the acquisition of 146 companies, the purchase of stakes in 61 companies, and a history of 25 divestments. Microsoft is an American public multinational corporation headquartered (headquarters pictured) in Redmond, Washington, US, that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions. Of the companies that Microsoft has acquired, 107 were based in the United States. Since Microsoft's first acquisition in 1987, it has purchased an average of six companies a year. The company has purchased more than ten companies a year since 2005, and it acquired 18 firms in 2006, the most in a single year, including Onfolio, Lionhead Studios, Massive Incorporated, ProClarity, Winternals Software, and Colloquis. Microsoft has made five acquisitions worth over one billion dollars: Skype, aQuantive, Fast Search & Transfer, Navision, and Visio Corporation. Microsoft has also obtained an 11.5% stake in Comcast for $1 billion, a 22.98% stake in Telewest Communications for $2.263 billion, and a 3% stake in AT&T for $5 billion. (Full list...)