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 retailer CarMax (KMX -1.49%) jumped as much as 13% today on a positive analyst report.

So what: ITG Research said that retail revenue growth is greater than expected and could set the company up to beat expectations. The company's tracking says that retail revenue growth is 16.7% versus an expectation of 13.3%.

Now what: ITG's numbers may turn out to be true but I would rather see strong data from the company before buying on a projection like this. Shares are trading at 16 times forward earnings, so if revenue is growing faster than expected then there could be a nice upside, but I'll wait to hear from management. Shares have lost some of their early gains, and like many analyst-induced pops I don't think today's will last.

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