7. SINA ( SINA) is an online media company operating through five business lines, namely SINA.com, SINA Mobile, SINA Community, SINA.net and SINA E-Commerce. On a year-to-date basis, the company surged 55.7% to touch 52-week highs in December. In comparison, counterparts like Sohu.com ( SOHU) and Google ( GOOG) gained 12.1% and lost 3.4%, respectively, on year-to-date basis. For the third quarter, the company posted a 12% year-over-year increase in net revenue, riding on the strong performance of online advertising. During the first three quarters of 2010, SINA ranked third in the online advertising market in China, with an 8.6% share, behind Baidu and Google. During November 2010, Microsoft announced a joint venture with SINA linking its instant messaging service and China's biggest microblogging service. The integration will include migration of Microsoft's blogging service and Windows Live Spaces to Sina's blogging service. This alliance is a part of Microsoft's global move to exit from the blogging business Looking ahead, the company is likely to gain with the launch of the highly popular microblog service in 2011. Weibo, a microblog similar to Twitter, which allows users to follow other users and view their posts, is likely to launch in 2011. Charles Chao, SINA's chief executive, said the overall advertising market is strong and fourth-quarter guidance relates to only some sectors and does not reflect the overall market. For the fourth quarter, SINA estimates revenues between $103 million and $106 million.