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 sports-apparel retailer Zumiez (ZUMZ 2.25%) jumped as much as 16% today after reporting better-than-expected same-store sales.

So what: The skateboard-and-snowboard specialist said that comparable sales increased 2.1%, while analysts had expected a drop of 7.5%. Total company sales for the five-week period ending April 6 increased 20%. The action sport retailer said both higher prices and greater unit sales helped drive the same-store sales improvement.  

Now what: Zumiez was one of a number of retailers to post better-than-expected same-store sales, helping to drive the broader market higher. One month's results do not make for a particularly strong investing thesis, and the company seems to have benefited from low expectations.  March is also a generally slow month for the retailer, which makes most of sales in the second half of the year, but expect analysts to raise their estimates for the quarter. Currently, the consensus is just $0.10 a share.

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