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 Chinese coal miner Yanzhou Coal Mining (NYSE: YZC) surged 10% in early trading today, as investors cheered the company's quarterly results.

So what: Driven by voracious domestic demand, Yanzhou's third-quarter earnings more than tripled from a year earlier, to $553 million. According to data from the China Coal Transport and Distribution Association, coal prices in China soared 28% percent in the quarter.

Now what: Yanzhou's Chinese exposure has certainly given its stock plenty of pop, but I'd use today's run-up to take some dough off the table. Over the past two years, Yanzhou is up a whopping 500%, while American coal counterparts Peabody (NYSE: BTU), Arch Coal (NYSE: ACI), and CONSOL (NYSE: CNX) haven't even doubled. While it might be tempting to keep a big bet on Yanzhou given China's dependency on coal, the stock is just too volatile (beta of 2.5) for the average investor's stomach.

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