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 Wi-Fi products maker Ruckus Wireless (NYSE:RKUS) plummeted 23% today after its quarterly results and outlook missed Wall Street expectations.  

So what: Ruckus' first-quarter revenue jumped 27%, but a 92% plunge in profit, coupled with downbeat guidance for the current quarter, reinforces recent concerns over slowing growth. The company cited weak Chinese demand and delays from its North American carrier customers for the gloomy report, raising plenty of uncertainty over its competitive position and general operating environment going forward.

Now what: Management now sees second-quarter adjusted EPS of $0.03-$0.04 on revenue of $61 million-$64 million, versus Wall Street's view of $0.04 and $67.1 million. "We believe that the fundamentals, growth drivers and long-term market opportunity for Ruckus remain intact," CEO Selina Lo reassured investors. "I believe we have significantly bolstered our technology differentiations and strengthened our competitive advantage in the growing market for public Wi-Fi access equipment." Given the strong headwinds clearly facing Ruckus at this point, however, I'd be highly cautious about buying into that bull talk.

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