Sina, the owner of the mainland's largest Twitter-like service, posted third-quarter profit that surpassed analysts' estimates after new mobile services helped lure more advertising. Net income more than doubled to US$25.4 million from US$9.88 million a year earlier, Shanghai-based Sina said in a statement on Tuesday. Analysts had projected a US$16.2 million profit. Sales rose 21 per cent to US$184.6 million, slightly above an estimate of US$178 million. Advertising revenue climbed 26 per cent to US$151.6 million. The company is collaborating with Alibaba, the country's largest e-commerce operator and a shareholder in Sina's Weibo microblogging service, to better compete with Tencent. "Sina's co-operation with Alibaba helped increase its advertising revenue," said Ricky Lai, an analyst at brokerage Guotai Junan. "Sina Weibo also monetised more online games provided on its platform." The company forecast fourth-quarter non-GAAP revenue of between US$190 million and US$194 million, including US$160 million to US$162 million from advertising. In April, Sina agreed to sell 18 per cent of Weibo to Alibaba for US$586 million. The two companies will also collaborate in areas including online marketing and payment, as more users turn to e-commerce on smartphones and tablets from personal computers. Alibaba began allowing shoppers to log on to its Taobao Marketplace e-commerce website in August using their Weibo accounts, after suspending sellers' access to Tencent's WeChat instant-messaging service.