What happened

It's a crazy day on the stock markets Wednesday, with the S&P 500 index inching modestly lower -- but shares of hydrogen fuel cell stocks going off like bottle rockets.

In early-afternoon trading, shares of fuel cell pioneer Ballard Power Systems (NASDAQ:BLDP) are up a strong 10.9%, while rival Plug Power (NASDAQ:PLUG) has risen 12.5%, and Bloom Energy (NYSE:BE) leaves everyone else in the dust -- up 16.5% as of 12:10 p.m. EDT. .

Cartoon fuel cell car on palm of hand putting out H2 bubbles as exhaust.

Image source: Getty Images.

So what

What gives? If you scan the news headlines today, you'll find nothing directly affecting any of these three stocks -- no analyst upgrades or price target increases, no positive press releases from management, and certainly no mention of positive earnings.

Nor is there even any hope for good earnings news anytime in the near future. Each of these three alternative energy companies has already reported earnings, with Bloom's report being the most recent at less than a month ago. None of these three companies had anything good to report, either. All three lost money in the latest quarter, and both Plug and Ballard lost even more money than analysts had feared they would.  

Meanwhile, macroeconomically speaking, oil prices are modestly lower. And since the appeal of alternative energy stocks depends largely on how attractive their cost might be relative to oil, cheaper oil is actually a negative for these stocks, not a positive -- and thus, does nothing to explain fuel cell stocks' popularity today.

Now what

What might explain it?

I don't know if you've noticed, but in recent days we've seen heightened interest in bankrupt stocks such Hertz and LATAM Airlines -- stocks carrying high levels of debt, and with it a better-than-average chance that investors in them will lose their shirts.

In that regard, both Plug and Bloom Energy, at least, also carry relatively high levels of debt. Ballard doesn't, but neither does it have any earnings to sustain it -- and neither does Plug or Bloom. Analysts polled by S&P Global Market Intelligence don't expect Ballard to earn anything before 2022, either, nor Plug or Bloom before 2023.

To me, that makes all three stocks look exceedingly risky to invest in -- but this market appears to be a "risk on" kind of a market, and if risk is what investors are looking for these days, these three fuel cell stocks have it in spades.