Shares of Hemispherx (NYSEMKT:HEB) climbed almost 200% in 2012 over investor excitement that the company would be resubmitting its chronic fatigue syndrome drug Ampligen for approval from the Food and Drug Administration. The FDA rejected the drug in 2009, citing insufficient efficacy and safety data, but rather than conducting further trials, Hemispherx attempted to simply rework the data it already had. Apparently, the agency disagreed with that approach as negative briefing documents ahead of Thursday's advisory committee meeting sent shares down 45%. In this video, Motley Fool health care analyst David Williamson takes us through just how bad the damage is.

David Williamson has no positions in the stocks mentioned above. Follow him on Twitter @MotleyDavid. Max Macaluso has no positions in the stocks mentioned above. The Motley Fool has no positions in the stocks mentioned above. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.