BEIJING, Feb. 25 -- 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 emerged hours after Sina Corp announced its financial results for the fourth quarter and the full year ending Dec. 31, 2013, which showed robust growth.

For the fourth quarter, Weibo's total revenues reached 71.4 million U.S. dollars, up 151 percent year on year and 33.7 percent quarter on quarter, resulting in a profit of 3 million U.S. dollars, according to Sina.

Revenues in the first three quarters last year were 25.8 million U.S. dollars, 38.6 million and 53.4 million respectively.

Weibo registered a profit for the first time in its history of more than four years in the fourth quarter.

Advertising revenues grew 163 percent year on year, or 28 percent quarter on quarter, to 56 million U.S. dollars in the fourth quarter, according to Sina.

Non-advertising revenues from Weibo's value-added services, such as Weibo membership fees and games, more than doubled, rising 114 percent year on year to 15.4 million U.S. dollars.

The planned listing comes at a tricky time for Weibo, as microblogging is seemingly in decline because of competition from the more private mobile messaging apps like Tencent Holdings Ltd's WeChat, or Weixin, in China.

Active users of microblogs in China fell by a tenth between 2012 and 2013, according to a report by the China Internet Network Information Center.

However, the number of Weibo's daily active users increased from 60.2 million at the end of September 2013 to 61.4 million by the end of the year. The number was 46.2 million at the end of 2012.

The number of messages posted daily by Weibo users increased from 86 million at the end of September 2011 to 130 million at the end of October 2013.

Cao Guowei, chairman and CEO of Sina, said robust growth of Weibo was the main cause for the whole of Sina to achieve strong revenues and profits in the fourth quarter.

Sina, which also runs a portal website, posted revenues of 197 million U.S. dollars for the fourth quarter last year, up 42 percent from the same period of 2012. For 2013, Sina's revenues reached 665.1 million U.S. dollars, up 26 percent from 2012, according to Sina.

In 2014, Sina will try to increase the number of Weibo users and their user time through innovative products, said Cao.

To provide better user experience, Weibo plans to make its platform more multimedia-based. News, music and video will feature more prominently in Weibo, he added.