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 office products distributor United Stationers (Nasdaq: USTR) jumped as much as 14% in intraday trading as investors reacted to the company's fourth-quarter results.

So what: Fourth-quarter revenue was basically flat with 2009, but the $1.2 billion tally matched analysts' estimates. After adjusting for certain one-time gains and expenses during the quarter, earnings per share were $1.17, 19% above last year and well ahead of the expected $1.07. The bottom-line gain was driven in large part by increased margins.

Now what: While the company didn't provide a bottom-line number for 2011 in its earnings release, management was generally upbeat about the year ahead. With the economy slowly recovering, management wants continued improvement and noted that first-quarter sales to date are up 3%. The company is also looking for further margin gains in 2011.

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.