Sina sells Weibo stake to Alibaba for $586m China's most popular social network has been valued at more than $3bn after Sina Corp sold an 18 per cent stake in its microblogging service Weibo to ecommerce group Alibaba for $586m. Nasdaq-listed Sina said it had also given Alibaba the option to raise its ownership in Weibo to 30 per cent "at a mutually agreed valuation within a certain period of time." The deal brings together Weibo, often described as the Chinese equivalent of Twitter, with Alibaba's eBay-like ecommerce platforms. The companies said the strategic partnership would generate $380m in advertising and other revenues for Weibo over the next three years. Jack Ma, chief executive and chairman of Alibaba, said: "We believe that this strategic alliance helps to create a stronger Weibo. It affirms our view of the vitality and importance of social media in unleashing value in ecommerce activities. Alibaba is expected to launch an initial public offering before the end of the year. Sina's shares jumped more than 15 per cent in morning trading on Monday, giving it a market capitalisation of about $3.8bn. Sina said late last year that Weibo had surpassed 500m registered users, 46m of which were daily active users.