What happened

Well, that was certainly disappointing.

After scoring big gains in each of the five trading sessions leading up to earnings day, FuelCell Energy (NASDAQ:FCEL) stock finally met its comeuppance on Wednesday, falling as much as 29.9%. Earnings for the fuel-cell pioneer's fiscal fourth quarter only missed expectations by a penny.

Still, that earnings miss, combined with an absolute decline in revenue of 38% and a net loss for the quarter, were enough to derail the stock's rally, sending FuelCell stock down 22.9% by the close of trading -- and subtracting a further 22.5% in market cap this morning, as of 10:50 a.m. EST.

An older woman falling down a flight of snowy steps outdoors

Image source: Getty Images.

So what

Worse, the damage hasn't been limited to FuelCell stock. In apparent sympathy with customers' weak enthusiasm for FuelCell's products, shares of peer fuel-cell companies Ballard Power (NASDAQ:BLDP) declined 8.8% yesterday, and are down another 10.6% today. Plug Power (NASDAQ:PLUG), yet another player in the fuel-cell game, ended up dropping 6.2% yesterday and is down another 2.6% today.

Adding to the misery, investment banker Craig-Hallum chose today to downgrade FuelCell stock (though not the others -- yet) to "sell," citing both the earnings miss and a sequential decline in backlogged work among its reasons.

Now what

And that's the good news. The bad news is that depending on when investors sold yesterday, their losses could have been even worse. All three of these stocks shed at least 10% in market cap in Wednesday trading, before paring their losses later in the day. That recovery, however, proved brief, and stock prices at all three fuel-cell companies are falling once again today, suggesting the losses may not be over just yet.

In particular, Plug Power is set to report its own (preliminary) full-year earnings results next Thursday, Jan. 30. Ballard hasn't announced an earnings date yet, but given that its Q3 results came out almost precisely three months earlier (Oct. 30), it's probably going to report on or about Jan. 30 as well -- so expect two more chances for weak results to pull down all three of these stocks in the coming days.

Or maybe -- just maybe -- a divergent result will stanch the bleeding? A Fool can hope.