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 coal producer Walter Energy (NYSE: WLT) sank 10% on Wednesday after the company cut its third-quarter earnings outlook.

So what: While Walter blamed the downside guidance -- management now expects to sell 5.2 million metric tons of coal versus previous forecasts for 5.9 million tons -- on record rainfall, Wall Street is also interpreting it as a sign of global coal demand weakness. In fact, coal peer Alpha Natural's (NYSE: ANR) stock is also down big today after the company cut its full-year production, specifically citing the slowdown in the Asian steel market.

Now what: I'd look at today's plunge as a possible entry point. Fellow Fool Matt Koppenheffer correctly cautioned Fools about buying into takeover rumors earlier this month, but with its stock once again flirting with 52-week lows, Walter is a tempting turnaround bet. Of course, with a beta of 2.2, expect the ride to be very bumpy.

Interested in more info on Walter? Add it to your watchlist.