NEW YORK ( TheStreet) -- Baidu ( BIDU) was tumbling 5.78% to $87 per American depositary share in afterhours trading after the leading Chinese Internet search engine posted lower-than expected first-quarter results as it continues to be challenged by up-and-coming players in the mobile-phone space. Still, Robin Li, the chairman and CEO of Baidu, said in a statement that the company's mobile offerings are making "exciting progress," with its flagship mobile-search product having now surpassed 100 million daily active users, which is more than a 25% increase from the end of the fourth quarter. "We remain committed to investing aggressively, particularly in marketing and R&D," said Jennifer Li, Baidu's CFO. "By deploying resources in the most strategically important areas of our business, we're confident we can build exceptional long-term value for shareholders." The company reported earnings per ADS of 95 cents and excluding share-based compensation expenses of $1. Revenue increased 40% to $961 million in the first quarter from a year ago. On average, analysts surveyed by Thomson Reuters were expecting earnings per ADS of $1.03 on revenue of $969.27 million. Baidu reiterated second-quarter revenue expectations in the range of $1.187 billion to $1.216 billion, vs. the consensus target of slightly more than $1.2 billion. Follow @atwtse -- Written by Andrea Tse in New York >To contact the writer of this article, click here: Andrea Tse.