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 mail-based marketing specialist Valassis Communications (NYSE: VCI) dropped as much as 10% in early trading today on very high trading volume.

So what: Hurt by the bankruptcy of a large client, Valassis missed analyst targets and its own guidance in this morning's fourth-quarter report. Moreover, the earnings forecast for 2011 came in below the Street's consensus.

Now what: The company has come a long way from teetering on the edge of bankruptcy in 2009 and is doing a fine job of restructuring its formerly crushing debt load. But Valassis is subject to the vagaries of a fickle market; junk mail marketing (to be blunt) can ill-afford large setbacks as it runs on vanishingly thin margins already. If you bought shares for less than $2 each in 2009, congratulations; but the long-term prospects for this company and its general market look grim.

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