Chinese internet company Sina plans to spin off its Twitter-like microblog service, Weibo, in a US initial public offering to raise US$500 million, a person with knowledge of the deal said on Tuesday. The person, who wasn’t authorised to speak publicly about the deal, said investment banks Goldman Sachs and Credit Suisse had been hired to manage the IPO in New York. The share sale, which has not been officially announced, is expected to be carried out in the second quarter. The company did not return a request by phone and e-mail for comment. The plans were first reported by the Financial Times on Monday. Sina’s IPO plans come as other Chinese internet heavyweights prepare for share sales. Alibaba, China’s largest e-commerce company, is planning an IPO that’s widely expected to happen this year and could value the company at more than US$100 billion. Alibaba bought an 18 per cent stake in Sina Weibo for US$586 million last April. Online retailer JD.com filed last month for a US stock listing. Chinese microblogs have enjoyed explosive growth as users have taken to social media to share information in a country where the internet is strictly regulated. But numbers have been crimped recently by tighter Chinese government controls on what can be posted and reposted. The microblogs had 281 million users at the end of last year, 9 per cent fewer than the year before, according to the China Internet Network Information Centre. The decline comes as Chinese web users shift to smartphone-based instant messaging services, such as Tencent’s WeChat, which has surged in popularity since 2012, threatening Sina Weibo’s dominance in information sharing. WeChat and similar apps are increasingly incorporating social media functions that resemble microblog features. Sina reported on Monday that fourth-quarter earnings jumped 18-fold to US$44.5 million as Weibo turned an operating profit for the first time thanks to rising revenue from advertising, games and VIP membership fees.