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 solid-state storage specialist SanDisk (Nasdaq: SNDK) sank 10% on Thursday after the company's quarterly results and guidance disappointed Wall Street.

So what: While SanDisk's fourth-quarter revenue jumped a solid 19% to $1.58 billion, a 140-basis-point drop in gross margins is triggering concerns about the company's long-term profitability. SanDisk sales have benefited from the growth of smartphones and tablets recently, but rising expansion costs, unfavorable exchange rates, and recently weakening demand from mobile customers are all headwinds that Mr. Market is going to pay more attention to.

Now what: Looking ahead, management now sees current-quarter revenue of $1.3 billion to $1.35 billion and full-year 2012 revenue of $6.2 billion to $6.6 billion -- both below analyst estimates. However, given CEO Sanjay Mehrotra's opinion that the "secular demand trends for NAND flash remain vibrant," today's pullback might provide a decent entry point for long-term Fools. And with the stock trading at a clear P/E discount to the sector, SanDisk seems like a relatively decent bet.

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