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 Clean Energy Fuels (Nasdaq: CLNE) climbed 13% again today in a continuation of yesterday's move.

So what: After climbing yesterday because of a financing deal with Chesapeake Energy (NYSE: CHK), the stock was given further fuel today when Bank of America upgraded the stock. In a rare move from the outhouse to the penthouse, Clean Energy Fuels was upgraded from underperform to buy by Bank of America's analysts.

Now what: Clean Energy Fuels now looks like a company that is going to make natural gas fuel available nationally almost by itself. The 150 stations that will be built because of Chesapeake's funding will help the company expand beyond mass-transit contracts faster than would have been possible before and should help the company's growth tremendously. The stock may have popped two days in a row, but I think there's still more room to run as natural gas becomes a viable fuel source nationwide.

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