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 coffee giant Starbucks (Nasdaq: SBUX) fell 10% today after the company issued earnings and a disappointing guidance.

So what: Fiscal-third-quarter revenue grew 13% to $3.3 billion and earnings per share rose 19% to $0.43 per share. The results were just short of expectations, but investors are eyeing the company's guidance as the reason to sell today. Management now expects fourth-quarter-revenue growth of 10%-12% and earnings per share of $0.44-$0.45. This is lower than previously expected.

Now what: The slow economy was blamed for the lowered forecast, and it got investors spooked today. But the foundation of Starbucks appears to still be strong and the company expects to grow double digits next year as well. With shares trading at 26 times 2012 estimates, I'm not rushing out to buy shares today, but I don't think the guidance numbers are a reason to panic either.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.