This paper examines whether marked-to-market values of energy trading assets and liabilities of companies that enter into energy contracts are related to market value of equity. The Emerging Issues Task Force of the Financial Accounting Standards Board ruled in November 2002 to ban the use of mark-to-market accounting for energy contracts out of concern that fair values can be easily inflated. We find that the excess of fair value over original value of energy trading assets and energy trading liabilities is not relevant for valuation. It may be inferred that fair values which are subject to management estimates and not verifiable are poor signals of worth and performance (Watts, R., 2003. Conservatism in accounting Part I: Explanations and implications. Accounting Horizons 17, 207-221).