What's happening: Clean Energy Fuels Corp (NASDAQ:CLNE) stock is moving again. As of this writing (1:45PM ET), it's up around 10%, after having spent most of the day above 11%. This marks the third day in July alone the stock has moved up more than 10%. That's the continuation of a pattern we've seen all year:

CLNE Chart

CLNE data by YCharts

Why it's happening: The only thing that today's move correlates with is a market day that ends in "y". 

Okay, in all seriousness, there's just not any news out there. Oil prices are up a bit, and natural gas remains very cheap, both of which are good for Clean Energy, but neither is a material enough move to be driving the stock up. But as I've written about several times before, this is a highly shorted stock, and it looks like there was a lot of buying activity earlier in the trading day. This could have been shorts exiting (you actually buy shares to exit a short position) or new investors buying, but chances are, it's probably a little bit of both. 

With earnings coming up on August 5, there are likely to be more days like this, but it's important for long-term investors to remember that the volatility is a reflection of investor (mainly short-term trader) mentality, and not a reflection of the business results changing from day to day.

If you're a shareholder, days like this can make it hard to not react, but if you're in it for the long haul, it's all about the business performance. And we didn't learn anything new today. 

Jason Hall owns shares of and options for Clean Energy Fuels. The Motley Fool recommends Clean Energy Fuels. 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.