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 marine fuel supplier Aegean Marine Petroleum Network (NYSE: ANW) plummeted 20% in intraday trading Thursday after forecasting a surprise loss for the fourth quarter.

So what: Thanks to higher expenses and continued softness in the maritime space, Aegean projected a quarterly loss of $0.22 to $0.24 per share, while analysts were expecting a profit of $0.13 per share. Ever-intensifying competition from integrated oil gorillas like BP (NYSE: BP) and ExxonMobil (NYSE: XOM) has also been weighing heavily on Aegean's bottom line.

Now what: Aegean is quickly becoming just too cheap to ignore. With today's massive 20% plunge, the shares have now fallen 70% over the past year and trade at roughly around book value. The short-term picture doesn't look particularly pretty, but with Aegean still expected to enter new global markets, the stock might be an attractive long-term value.

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Fool contributor Brian Pacampara owns no position in any of the companies mentioned. The Fool owns shares of Exxon. Try any of our Foolish newsletter services free for 30 days.

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