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: Oil and gas explorer Magnum Hunter Resources (AMEX: MHR) popped as high as 11% in intraday trading after a Wall Street analyst upgraded the stock.

So What: With the first three of Magnum Hunter Resources' Eagle Ford wells and the first two West Virginia Marcellus wells all scheduled to come online this quarter, Jefferies Group upgraded the stock to a buy. For such a small company, these new wells obviously represent a huge increase in production.

Now What: If the Jefferies price target truly represents Magnum Hunter Resources' return potential, there isn't much of it left. Today's move already puts the stock at around $4.65, which is just shy of the analyst's price target of $4.80. In fact, these shares are already up a whopping 200% in 2010. While Magnum Hunter Resources' shares could certainly keep rocketing, I'd go with the likes of National Fuel Gas (NYSE: NFG), EOG Resources (NYSE: EOG), and even Chesapeake Energy (NYSE: CHK) as more stable bets on the Marcellus.

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