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 staffing firm On Assignment (NYSE:ASGN) fell 11% today, after reporting earnings.

So what: Fourth quarter revenue rose 1.6% sequentially, to $401.7 million, which was at the high end of the company's estimates. The problem is that net income was only $11.3 million, or $0.21 per share, and Wall Street was expecting $0.28 per share.  

Now what: Net income was up from $7.5 million a year ago, but with the stock trading at 25 times earnings, there was more growth expected. It's also not encouraging that management expects net income to fall to $8.8 million to $10.5 million -- or $0.16 to $0.19 per share -- next quarter, when analysts are expecting $0.23 per share in earnings. I don't think there's any reason to buy today on slow growth and disappointing earnings.

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