#4 Microsoft

This software giant’s sites like MSN, Hotmail and Bing had more unique visitors in December 2012 than any other web property except for Google and Yahoo!. The Microsoft sites attract 4.9 percent of the time online, backed with 170.9 million desktop visitors and 55.2 million mobile visitors.

Bing, the second-most popular search engine behind Google, has seen its share of search grow slightly, from 15.1 percent of all searches in December 2011 to 16.3 percent in 2012. Microsoft has made a major push into mobile with its new Windows Surface Tablet, which was released late in 2012.

#3 Yahoo!

Yahoo, though lost its advertising market to Facebook and Google, it is still the most popular portal on the Web. The portal has garnered about 7 percent of the online time, with 185.8 million desktop visitors and 92.2 million mobile visitors.

The company recently redesigned its web site to make it more personalized. The site includes a live news feed customized to visitors' interests and to what their friends share on social networks. The company has made significant strides in mobile as well.

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