By market close Tuesday, shares were crushed 41.3% to $6.05.
Trading volume of 230.6 million was more than six times its three-month daily average.
In the research report Tuesday, Citron Research notes Plug Power would be fairly valued at 50 cents, a blended average of recent capital raises, a far cry from Tuesday's open of $11.44.
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Since the 2000 crash, Citron estimates the company has lost close to $850 million and has yet to develop intellectual property or "meaningful revenue growth."
The Latham, N.Y.-based business is due to report earnings before the bell Thursday, but Citron urges investors to distrust management's guidance due to a "history of broken promises and failure to deliver."
Analysts surveyed by Thomson Reuters forecast Plug Power to post a net loss of 8 cents a share in the three months to December and 48 cents a share over fiscal 2013.