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 Teradata (TDC 0.27%) plummeted 17% this morning after the data management specialist lowered its outlook for 2013.

So what: The stock has pulled back significantly in recent months on concerns over slowing growth, and today's downbeat guidance -- prompted by disappointing third-quarter demand -- only reinforces that worry. In fact, Teradata said third-quarter revenue from the Asia, Pacific, and Japan markets dropped 21%, while it fell 19% in the Middle East and Africa segment, suggesting that gorilla rivals like Oracle continue to pressure its market share position overseas.

Now what: Management now sees 2013 adjusted earnings per share of $2.70-$2.80 on flat revenue of $2.67 billion, well below its prior view of $3.05-$3.20 and 6% revenue growth. "Although we were disappointed with our preliminary results for the third quarter of 2013, we were pleased with our performance in Europe and in the U.S., which are our two largest markets," CEO Mike Koehler reassured investors. "We remain confident in our competitive position in all the markets we serve over the long term." More important, with the stock hitting a new 52-week low today and trading at a forward P/E of 13, Mr. Market's near-term concerns might provide a cheap opportunity to bet on that bullishness.