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 auto parts retailer Advance Auto Parts (NYSE:AAP) climbed as high as 10% today after its quarterly earnings easily topped Wall Street expectations.

So what: The stock has slumped over the past year as rebounding demand for new vehicles has hurt sales for used auto parts, but a wide fourth-quarter profit beat -- EPS of $0.88 versus the consensus of just $0.76 -- suggests that things are starting to pick up. In fact, close rival O'Reilly Automotive (NASDAQ:ORLY) is also surging today on better-than-expected results, giving Wall Street a particularly good feeling about the industry as a whole.

Now what: Management now sees full-year 2013 adjusted EPS of $5.45-$5.60, versus Wall Street's view of $5.57.

"Our decision to maintain our investment profile through the course of the year is driven by our confidence in the long-term industry fundamentals and provides us with a strong foundation to build upon as we head into fiscal 2013," said Vice President and CFO Mike Norona.

More important, with the stock still down about 20% from its 52-week high and trading at a forward P/E of 13, buying into that optimism won't come at too high of a price.

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