Plug Power shares are down 34% after surging earlier this morning.
Ballard, which supplies Plug Power with fuel cells, is down 20%. FuelCell Energy is down 17%.
We explained why fuel cell shares had recently been lifted — demand seemed to be picking up for a number of reasons.
But the shares have also been subject to heavy short interest, according to Karl Loomes, a market analyst at SunGard’s Astec Analytics.
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