Corporate valuations and the Merton model

In recent years both practitioners and academics have realized that traditional discounted cash flow models erroneously consider the option value embedded in firms. Hence equity and debt valuation methodologies based on option theory have recently become quite popular. Such methodologies take inspiration from the Merton (1974) model which was originally introduced to measure the impact of default risk on corporate bonds yields. Thirty years later the Merton model for its simplicity and rigour remains unrivalled and is the basis of some of the most sophisticated credit risk models. In this paper it will be shown how practitioners often improperly adapt the Merton model for aims beyond its original scope. © 2007 Taylor & Francis.