fridays foibles, page-40

"that for every short seller there must necessarily be a buyer"

This isn't the case where the company goes bankrupt or is otherwise wiped out. If a financial institution is sold into the ground (using stock that doesn't even exist) it may be forced into this situation. Quite likely it will have its rating cut and people will think twice about doing business with it. Before you know it the share price decline becomes a self-fulfilling prophecy.