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 InnerWorkings (NASDAQ:INWK) were falling apart today, dropping as much as 25% after the promotional specialist cut its full-year guidance ahead of its first-quarter report.

So what: InnerWorkings, which provides printed and promotional materials for businesses, said that it was trimming its 2013 to revenue outlook to a range of $900 million to $930 million, down from a previous range of $930 million to $960 million, and revising EPS guidance to $0.45-$0.50 from a previously projected range of $0.57-$0.61. InnerWorkings said the lower guidance was due to a change in management at a large client, and its decision to do some of its business with one of InnerWorkings' competitors.

Now what: Even with the drop in revenue and profit expectations, InnerWorkings still sees EPS increasing by 10% to 22% this year. Today's drop may be hard to stomach for shareholders, but the loss of the client doesn't point to any other structural weaknesses in the company. Its recent acquisition of DB Studios should provide an additional growth outlet. At this point, there seems to be no good reason to sell.

Stay up to date on Innerworkings. Add the company to your Watchlist by clicking here.  

Fool contributor Jeremy Bowman and The Motley Fool have no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.