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 Barrett Business Services (BBSI -0.51%) fell 13% today after the company released preliminary fourth-quarter results.

So what: Management said net revenue was up about 27% from a year ago to $144.5 million and non-generally accepted accounting principles rose an estimated 31% to $779.3 million. Diluted earnings per share are expected to be $0.71-$0.73 after accounting for a $5.1 million increase in workers' compensation self-insurance, which will lower earnings by about $0.42 per share.  

Adjusted earnings per share of $1.13-$1.15 are still below Wall Street's estimate of $1.17 per share.

Now what: Note that there's only one analyst covering Barrett so there weren't a lot of opinions to compare results against. Taking the revenue growth into account, I don't think there's much to worry about and wouldn't be selling today. Management will go into more detail on the quarterly results when earnings are released on Feb. 5. That's when investors will know more about whether to change their investment theses. Missing one analyst's guess at earnings isn't a reason to panic.