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 specialty retailer Bed Bath & Beyond (BBBY) plunged 13% today after its quarterly results and outlook disappointed Wall Street.

So what: The stock has been sluggish in recent months on concerns over slowing growth, and today's third quarter results -- profit edged up 2% on a revenue increase of just 6% -- coupled with downbeat guidance only reinforce those worries. In fact, same-store sales rose just 1.3% versus 1.7% in the year-ago period, suggesting the company's competitive position is weakening a bit.

Now what: Management now sees full-year EPS of $4.79-$4.86, down from its view of $4.88-$5.01, and below the Wall Street consensus of $5.02. "We believe that throughout the United States and Canada, there is an opportunity to operate in excess of 1,300 Bed Bath & Beyond stores, as well as grow our World Market, Christmas Tree Shops or andThat!, and buybuy BABY concepts from coast to coast," Co-Founder/Co-Chairman Leonard Feinstein reassured analysts in a conference call. "We remain committed to and are excited about the continued growth of all our merchandise categories."

More important, with the stock now off about 15% from its 52-week highs and trading at a cheapish forward P/E of 12, now might be an opportune time to buy into that bullishness.