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 fuel cell developer FuelCell Energy (Nasdaq: FCEL) were electrifying today, gaining as much as 35% in intraday trading on heavy volume.

So what: FuelCell announced today that POSCO (NYSE: PKX) subsidiary POSCO Energy placed an order for 70 megawatts of fuel cell kits. The order is expected to be fulfilled over a two-year period and is estimated to be worth $129 million to FuelCell.

Now what: This is the largest order that FuelCell has ever received and dwarfs the $83 million in total revenue that the company reported over the 12 months ending in January. The company is neither profitable nor cash-flow positive, but management hopes that the higher production levels demanded by orders like this will help drive efficiencies and reduce costs.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.