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 temporary worker specialist SFN Group (NYSE: SFN) were told "You're fired!" by investors today, falling as much as 21% in intraday trading after the company announced first-quarter results.

So what: SFN did a better job in the first quarter of turning its revenue into profits as it reversed a loss from last year, matching analysts' earnings per share estimates. The company's revenue also moved in the right direction, rising 8.1% year over year to $500 million. That revenue tally, however, was short of Wall Street's $525 million target.

Now what: The look ahead to the next quarter isn't much more encouraging from a top-line perspective. At the midpoint of management's guidance, the company would see 3.5% year-over-year revenue growth during the quarter, which would put sales at $532 million -- once again short of Wall Street's estimates. The company does expect that it will continue to improve profitability, but it appears that investors were expecting growth a bit more robust than what SFN has been able to muster.

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Fool contributor Matt Koppenheffer does not have a financial interest in 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.