Sina Corp, which runs the biggest website on the mainland, said second-quarter profit surged 38.4 per cent as more companies bought online advertisements.
Net income rose to US$14.5 million from US$10.4 million a year earlier, beating the US$12 million estimate in a Bloomberg analyst survey.
Sales rose 11 per cent to US$59.8 million and the firm estimated that third-quarter revenue would range between US$63 million and US$65 million.
'This is the low end of market estimates,' said Dick Wei, China internet analyst of JP Morgan.
Shares of Sina dropped 4.9 per cent to US$39.62 in after-hour trading on the Nasdaq on Monday.
Its key income driver in the second quarter was online advertising, which grew more than 40 per cent and generated 68.9 per cent of total revenue.