A major short attack (with follow up) that also lead to some retail bleeding.
This is part of my major issue with how shorting is implemented; while there can be substantial risk, institutions and large private players can short so much at one time that it creates a massive fear-based sell-off.
It's a self-fulfilling prophecy at that point. They'll eventually cover and the resulting large buy will signal the "recovery" that shouldn't have been necessary in the first place.
Over the long term it isn't that important, but as investment timeframes have shortened, the effects of shorting are dramatically exaggerated.
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