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 luxury handbag maker Coach (NYSE: COH) plunged 17% on Tuesday after its quarterly sales came in below Wall Street expectations.

So what: Strong sales overseas helped boost Coach's first-quarter profit 24%, but sluggish U.S. demand is triggering serious concerns over high-end spending. While sales in Japan and China spiked 16% and 60%, respectively, management had to lure cost-conscious North Americans away from cheaper rivals with increased promotional activity, raising worries about profitability going forward.

Now what: I'd look into today's big plunge as a possible buy-in opportunity. "Our goals remain unchanged," Chairman and CEO Lew Frankfort reassured investors. "We're committed to achieving double-digit top- and bottom-line growth over our planning horizon. We have a business model that generates significant cash flow and we're in a position to invest in our brand while continuing to return capital to shareholders." When you couple Coach's still-solid fundamentals with its cheapish forward P/E of 12, buying into that long-term bullishness might not be a bad idea.  

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