What happened

Yesterday was a great day to own unprofitable story stocks in the fuel cell sector. Shares of Ballard Power Systems (NASDAQ:BLDP), rival Plug Power (NASDAQ:PLUG), and the newest entrant to the sector, Bloom Energy (NYSE:BE), all notched gains of 10% or more.   

Today, that's all changed. Bloom Energy shares are down 9.8% around 12 p.m. EDT. Plug stock is off 12.4%, and Ballard shares are plunging 13%.

Here's why.

3 red arrows going down and crashing through the floor

Image source: Getty Images.

So what

Yesterday, there was no news to explain why shares of Ballard Power, Plug Power, or Bloom Energy zoomed. Conversely, today there's no news to explain why these particular stocks are falling -- no earnings reports, no earnings warnings, and not a peep out of Wall Street encouraging investors to either buy or sell the stocks.

Yesterday, though, was what stock market investors refer to as a "risk-on" day -- a day when investors turn into speculators, and buy the riskiest of stocks with the mentality that greater risk will bring greater reward. Today, on the other hand, is a "risk-off" day -- in which investors focus on what might go wrong, and how much money they might lose when it does.

Now what

And let me say this straight out: There is a lot that could go wrong with these three stocks. According to data from S&P Global Market Intelligence, it's been more than a decade since Ballard Power last reported a full-year profit from its fuel cells business. Bloom Energy and Plug Power haven't reported profits ever. Ballard isn't expected to turn profitable before 2022 at the earliest, and Bloom and Plug not before 2023, if then.

This situation gets even more serious when you consider that both Bloom and Plug are entering a recession carrying heavy levels of debt, but with no profits to pay it down. Ballard Power's situation is a bit less precarious -- it's got $18 million in debt, but $182 million in cash, and is only burning cash at the rate of about $29 million a year, so immediate bankruptcy shouldn't be a concern.

Of the three, I'd say that Ballard Power's position is the least insecure, but all three of these stocks look riskier than the average equity, and on a risk-off trading day, that's simply not the kind of stock investors want to own.