Facebook keeps running away with social media market share. Experian Hitwise announced today that Facebook accounted for 58.59 percent of all U.S. visits out of 155 social networking Web sites in September 2009. The 58 percent was the highest among all social networking sites sites, as U.S. visits to Facebook increased 194 percent in September 2009 compared with September 2008. MySpace received the second-highest market share of U.S. visits for the month, with 30 percent.

Tagged received 2.38 percent of visits in September 2009, the third-largest amount. Twitter had the largest percentage gain in market share of visits among the top five visited Web sites, increasing 1170 percent compared with September 2008. U.S. visits to social networking Web sites increased 62 percent in September 2009 versus September 2008 among the custom category of 155 of the leading social networking sites.

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