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 closeout retailer Tuesday Morning (Nasdaq: TUES) cratered today, falling as much as 22% in intraday trading after the company offered guidance for its fiscal second quarter.

So what: The company said that sales for the December quarter came in at $279 million, down from $290 million the prior year. Same-store sales for the quarter fell 3.2%. Along with the sales figure, the company also provided a range of $0.39 to $0.41 for the quarter's earnings per share. That compares with analyst expectations of $0.49 and the previous-year's result of $0.43.

Now what: There's good reason for investors to be miffed about today's news. The December quarter is by far the company's most important in terms of both revenue and profitability, so weaker-than-expected results during that period are a big disappointment. If there's a saving grace for Tuesday Morning, it's that -- at least as of the end of last quarter -- it's still in a pretty strong financial position with little debt hanging over its head. But management will now have to prove to investors that this soft quarter isn't a sign that the company's bottom line is continuing to sputter.

Want to keep up to date on Tuesday Morning? Add it to your watchlist.