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 biodiesel maker Renewable Energy Group (NASDAQ:REGI) jumped 15% today after the company reported earnings.

So what: The company sold 39 million gallons of biodiesel during the quarter, up 14% from a year ago, and net income rose from $14 million, to $46 million. On a per share basis earnings were $1.25 versus an expectation of $0.51 from Wall Street. 

Now what: The government retroactively reinstated the Biodiesel Mixture Excise Tax Credit, which accounted for the big jump in profit. Still, the strong increase in revenue is a positive sign, and the tax credit will give the company some stability this year. My biggest problem is the dependence on a tax credit, which will keep me from buying shares, because it's at the whim of Congress, not a position I want to be in with a big budget deficit in Washington.

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