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 Ballard Power Systems (NASDAQ:BLDP) rose by as much as 10% Thursday on the back of Wednesday's 60% gain following the announced deal between it and Volkswagen.

So What: Have you ever been to a party that is starting to die down toward the end of the night and then that one person shows up late and tries to keep it going? Yeah, this is pretty much the only explanation that can be tied to Thursday's stock price movement. For over a year now the stocks of fuel cell manufacturers have been surging on "huge" announcements that business is picking up and we're about to see big improvements on both the top and bottom line. The problem is these announcements are simply coming too few and far between to really make headway. 

Last year was a great example of this. We saw massive surges in stock price in just a few months, only to slowly peter out over time as quarterly earnings numbers came in and didn't quite live up to the expectations these deals suggested.

Now What: Investors in Ballard or any other fuel cell company are going to see these wild swings for a long time. Until the company's revenue and earnings start to show signs of steady growth and start to drive the direction of the stock instead of speculative deal announcements, it's probably best to sit on the sidelines for this one.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.