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 REX American Resources Corp (NYSE:REX) jumped 21% today after announcing fiscal third quarter earnings.

So what: Net sales fell 6.9% to $166.5 million, falling well short of the $189.9 million analysts expected. But net income increased from $0.4 million a year ago to $9.9 million, or $1.21 per share. That crushed the $0.73 expectation from analysts.  

Now what: Gross margins were up significantly and management is expecting a strong harvest to result in lower input costs in the future as well. The downside is that the EPA has recently proposed reducing the amount of biofuels required to be blended with oil, which would reduce demand. This quarter looks positive, but the long-term viability of ethanol is what I question and is why I'm not buying the stock's bump today.

Fool contributor Travis Hoium has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.