I define and analyze the agency costs of overvalued equity. They explain the dramatic increase in corporate scandals and value destruction in the last five years; costs that have totaled hundreds of billions of dollars. When a firm's equity becomes substantially overvalued it sets in motion a set of organizational forces that are extremely difficult to manage—forces that almost inevitably lead to destruction of part or all of the core value of the firm. WorldCom, Enron, Nortel, and eToys are only a few examples of what can happen when these forces go unmanaged. Because we currently have no simple solutions to the agency costs of overvalued equity this is a promising area for future research.