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 Patriot Coal (NYSE: PCX) are up 15% on buyout rumors circulating through the industry.

So what: The rumor is that Anglo American is interested in buying Walter Energy (NYSE: WLT), Patriot's competitor, setting up a buyout frenzy. This would continue consolidation that went on this summer when Alpha Natural Resources (NYSE: ANR) and Arch Coal (NYSE: ACI) completed large acquisitions.

Now what: Rumors are a lot of fun if you own shares, but right now there are no real facts behind today's move. The Times of London helped fuel the fire of a Walter Energy buyout rumor and Patriot Coal's shares came along for the ride. I would be careful buying on rumors because if they turn out to be false, shares will be right back where they started.

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