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 chipmaker Xilinx (NASDAQ:XLNX) plummeted 15% today after its quarterly results and outlook disappointed Wall Street.

So what: Xilinx's Q1 EPS of $0.62 managed to edge estimates, but a wide miss on the top line -- revenue of $612.6 million versus the consensus of $631 million -- coupled with downbeat guidance, reinforces concerns about softening demand going forward. While management's cost reduction efforts resulted in a year-over-year improvement in both gross and operating margin, analysts are worried that unfavorable wireless infrastructure trends will continue to dampen Xilinx's growth prospects.

Now what: Management now expects Q2 revenue to be flat to down 4% sequentially, versus the average analyst estimate of 2.2% growth. "June quarter revenues were affected by weaker than anticipated sales from our defense and wireless businesses," said President and CEO Moshe Gavrielov. "Looking ahead to the second half of our fiscal year, I believe Xilinx is positioned to benefit from a recovery in wireless and defense programs as well as improved business conditions in wired communications and industrial applications." When you couple the wireless headwinds facing Xilinx with its steepish PEG above 1.5, however, I'd hold out for an even wider margin of safety before buying into that turnaround talk. 

One way to profit from the stock market's biggest movers
Growth stocks pop and plunge on a daily basis, and weeding out the winners from the losers can seem daunting. The Motley Fool's Rule Breakers team can help. The team of analysts has uncovered high-growth stocks time after time, with Chipotle up more than 800% since its recommendation in 2007, and Baidu up a whopping 2,000% since its recommendation in 2006. Fortunately for you, the team believes it has found its next big winner. Click here for your copy of this timely report.

Brian Pacampara has no position in any stocks mentioned. The Motley Fool recommends Baidu. The Motley Fool owns shares of Baidu. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.