Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Chinese microblogging company Weibo (WB 1.11%) sank 10% today after its quarterly results and outlook disappointed Wall Street.

So what: The stock has been sluggish since its April IPO on valuation worries, and today's first-quarter results -- net loss more than doubled to $47.4 million despite a 161% revenue spike -- coupled with downbeat guidance only reinforce those concerns. Weibo grew its monthly active users by 34%, to 143.8 million, but Mr. Market's response suggests the company isn't growing fast enough to justify its seemingly lofty price multiples.

Now what: Management now sees current-quarter revenue of $74 million to $76 million, below the Wall Street consensus of $78 million. "Weibo is already the largest platform in China for users to create and distribute content publicly," CEO Gaofei Wang said in a conference call with analysts. "Our core strategy in the coming few years is to take advantage of the rapid growth of China's mobile Internet user base and leverage the core attributes of our platform." Given Weibo's highly speculative nature and still-pricey valuation, however, conservative Fools would do well to remain on the sidelines.