EFF: It gives investors a good estimate of what a financial institution is worth. It has more flexibility than commonly realized, especially for illiquid assets, where best estimates of value can be used.
KRF: There is not enough empirical evidence to be sure who is right about this issue, but we can guess. Those against marking to market argue that the transaction prices for securities sold under duress do not reflect their true value. If you and I both own relatively illiquid assets and you choose to sell yours quickly at a fire sale price, mark to market accounting may force me to write down the value of my assets to your transaction price. Unless I also plan to sell my position quickly, this undervalues my position. The critical question, however, is whether your transaction price is more accurate than the model value I would use if I am not forced to mark to market. My guess—and this is only a guess—is that the observed transaction price is typically more accurate than the model. In other words, marking to market would improve the accuracy of my balance sheet.
Eugene Fama and Ken French are members of the Board of Directors for and provide consulting services to Dimensional Fund Advisors LP.