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 Cemex (NYSE: CX) plunged by almost 13% this morning before reversing course and popping by as much as nearly 10% in volatile trading on fears that the company will not be able to meet its debt obligations.

So what: The Mexican cement maker has hit 13-year lows as slowing growth in the United States, and Europe may put a damper on the company's prospects going forward. Meanwhile, Cemex carries roughly $17 billion debt on its balance sheet, which is more than 7 times the company's EBITDA.

Now what: Cemex nearly defaulted on its debt back in 2009, so it's not out of the question to be concerned with the heavy burden. Management has vowed to bring debt down to under 7 times EBITDA by the end of the year. If the company fails to meet its debt covenants, its creditors could make life much harder for the 105-year-old company by requiring immediate repayment or demanding higher yields.

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