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 oil and gas producer Berry Petroleum (NYSE: BRY) fell 12% today, after reporting earnings.

So what: In the third quarter, revenue rose 6.6%, to $244.8 million, barely topping estimates. But that didn't translate to the profit that investors expected, and adjusted earnings per share of $0.71 fell $0.08 short of estimates.

Now what: The good news is that Berry is still profitable at these low energy prices, unlike a lot of its competitors. Analysts are expecting $3.37 per share in earnings this year and, even if the company falls short because of this quarter, the stock will still trade at just over 10 times earnings. I think that gives Berry nice upside if commodity prices improve, and makes today's dip a nice buying opportunity for investors.

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