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: Leading natural gas vehicle fuel provider and station builder Clean Energy Fuels Corp's (NASDAQ:CLNE) stock is up almost 10% today. So far in 2015, the stock is up almost 32%, though it's still well off prior years' highs. 

So what: The company issued a press release today announcing that it had opened several new refueling stations, and that it had secured refueling agreements with a number of major fleet operators, ranging from public transit to waste removal to heavy trucking. Combined, the new agreements announced would add roughly 2 million annual gallons in new fuel sales. 

Now what: Including the really big deal with Raven Transportation announced two weeks ago, Clean Energy has added about 4.5 million gallons of new annual fuel sales in recent weeks, with the majority of that coming from the heavy trucking segment, which represents a massive 35-billion-gallon-plus annual market. Even after the big jump, it looks like a good time to invest in the company, which has seen its stock trade roughly in line with oil prices over the past year, even though its product -- natural gas -- remains cheaper than diesel and gasoline. 

Looking ahead, the biggest concern for the company in the near term is probably its 2016 secured notes; it will probably have to come up with roughly $150 million to pay them back. With strengthening results and solid growth, chances are management will be able to refinance that debt, and potentially at even better terms. Either way, there's still risk, and I'd suggest easing into the stock until the company shows long-term profitability.