A technique is presented for deriving equilibrium models of asset risk premia in continuous time models which does not require the complete solution of a consumer's continuous time stochastic control problem. The technique is used to show that even if traders have heterogeneous information about asset returns and/or there are non-traded assets, then the risk premium of a traded asset is determined by the covariance between the asset's return and the rate of change in per capita consumption. We only require the assumption that traders' consumptions and traded asset values form an Ito process.

The potential performance of an asset set may be obtained by choosing the portfolio proportions to maximize the Sharpe (1966) performance measure. If a portfolio has a Sharpe measure equivalent to the potential performance of the underlying set of assets, then it is efficient. Multivariate statistical procedures for comparing potential performance and testing portfolio efficiency are developed and then evaluated using simulations. Two likelihood ratio statistics are then used to compare stock and bond indices against sets of 20 and 40 portfolios. The procedures are also compared to the Gibbons (1982) methodology for testing financial models.

The purpose of this paper is to reexamine Reinganum's study which indicates that abnormal returns could not be earned unexpected quarterly earnings information, and to document precisely the response of stock prices to earnings announcements. This study, using a very large sample of stocks and daily returns, represents the most complete and detailed analysis of quarterly earnings reports that has been performed to date. Our results are contrary to those of Reinganum and show that abnormal returns could have been earned almost any time during the 1970's. Our analysis also indicates that risk adjustments matter little in this type of work. Finally, we find that roughly 50% of the adjustment of stock returns to unexpected quarterly earnings occurs over a 90-day period after the earnings are announced.