By market open, shares had tumbled 9.7% to $18.28.
The company, 57%-owned by Sina Corp (SINA), expects to generate second-quarter revenue of $74 million to $76 million. Analysts surveyed by Yahoo! Finance expected revenue of $77.85 million.
However, the micro-blogging site did report better-than-expected results in its first quarter. Over the three months to March, Weibo reported a net loss of 3 cents a share, 2 cents narrower than analysts' consensus. Revenue of $67.5 million was 161% higher year over year.
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