What happened

The market appears to be ending this week not with a bang, not with a whimper, but with a painful howl of agony.

All major indexes -- the Dow, Nasdaq, S&P 500, Russell 2000, take your pick -- are down at least 2% in the final hour of the trading week. And just like last week, fuel cell stocks are taking it on the chin, with shares of Ballard Power (BLDP -1.29%) down 8.9%, FuelCell Energy (FCEL -3.08%) off 9.6%, and Bloom Energy (BE 0.45%) reeling 11.4% lower as of 3:15 p.m. EST today.

3 red arrows going down and crashing through the floor

Image source: Getty Images.

So what

The COVID-19 coronavirus is the culprit. At last report, the World Health Organization had confirmed cases worldwide above 99,000 (other sources are saying we've already passed the 100,000 mark). Deaths hit 3,400 today, and 90 countries are now reporting cases of COVID-19 within their borders.

Three countries outside of China now have reported infections in the thousands: Italy, Iran, and South Korea. Another half-dozen or so are counting by the hundreds -- and by all indications, all of these numbers are continuing to rise by the day.  

Now what

It's not a great time to be invested in the stock market, or it certainly doesn't feel like it. But things will get better. The world, and its stock markets, have weathered multiple health crises similar to COVID-19 in the past. (Remember SARS? Remember the bird flu? No one worries too much about either of those today.)

The key to surviving to enjoy the eventual stock market rebound, though, is probably to stick with companies earning consistent profits, and carrying light debt loads. Right now, neither Ballard, FuelCell Energy, nor Bloom Energy meet both those criteria. Ballard, with no profits and no free cash flow but nearly $150 million in the bank against only $20 million in debt, at least doesn't have to worry about running out of cash in the near future.

If you're persuaded that fuel cells are the future, and are looking to own the most likely survivor, Ballard may be your best bet out of today's fuel cell losers.