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 Cliffs Natural Resources (NYSE: CLF) fell as much as 12% today after the company reported earnings.

So what: Revenue fell 10% to $1.6 billion in the second quarter, well below the $1.76 billion analysts had expected. Net income was $258 million, or $1.81 per share, which was better than the $1.77 estimate, but it was down dramatically from $2.94 per share a year ago.

Now what: Falling prices were the driver of this quarter's disappointing results and offset increased volume. The company will also cut production at one of its coal mines because of weak demand, which has crushed coal miners this year. Right now the stock looks like a value, trading at just four times forward earnings estimates, but estimates are falling quickly, and this looks like a value trap to me. I'm going to stay away from this discount and wait for improving results before considering shares.

Interested in more info on Cliffs Natural Resources? Add it to your watchlist by clicking here.