What happened

Shares of hydrogen fuel-cell maker Plug Power (NASDAQ:PLUG) gained a healthy 9.2% in October, rising from $2.61 per share at the start of the month to $2.85 per share at the end -- and that's not even the amazing thing. At one point early in the month, Plug Power stock was up nearly 14% from its starting price, and over the past two weeks, the stock has surged as much as 13%.

But neither of those two factoids are the amazing thing, either.

Man walking along a path of red dice

Plug Power stock went on another random walk last month. Luckily for investors, this time it walked up. Image source: Getty Images.

So what

No, the really amazing thing about all these sharp movements in price at Plug Power stock is that they were entirely unexplained by any news  of any sort that would explain their rise. No insider buying. (That was last month.) No earnings announcements. (That comes later this month). 

No news of any kind.

Now what

It almost goes without saying that preceding pretty much all of these sharp rises in the price of Plug Power stock were equally dramatic downturns in Plug Power's share price -- and likewise on no news of note. In fact, this is probably the most important lesson that investors can learn from Plug Power's stock movements last month: Sometimes, stocks move up or down for no good reason at all.

Such movements aren't necessarily evidence of "shorts" at work, or of bankers on Wall Street who know something you don't. They're evidence of nothing more than the fact that Princeton Professor Burton Malkiel was right when he observed that stocks sometimes stagger along in an entirely random walk.

My advice? Don't waste time trying to find sense in senseless stock price movements. Real news will appear soon enough. To wit, Plug Power reports its third-quarter 2017 earnings on Nov. 8.

Rich Smith has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.