Sina Weibo, China's version of Twitter, is planning a stock market listing in New York "relatively soon", a source told Xinhua on Tuesday. The initial public offering, which will look to raise about 500 million U.S. dollars, is scheduled to happen in the first half of the year, possibly in May, added the source on condition of anonymity. The news came hours after Sina Corp announced its financial results for the fourth quarter and the full year ending Dec. 31, 2013, which showed robust growth.