Testing Asset Pricing Models with Changing Expectations and an Unobservable Market Portfolio

When the assumption of constant risk premiums is relaxed, financial valuation models may be tested, and the risk measures estimated without specifying a market index or state variables. This is accomplished by examining the behavior of conditional expected returns. The approach is developed using a single risk premium asset pricing model as an examle and then extended to models with multiple risk premiums. The methodology is illustrated using daily return data on the common stocks of the Dow Jones 30. The tests indicate that these returns are consistent with a single, time-varying risk premium.