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.

This paper studies the consequences for the behaviour of aggregate output of the perception on the part of firms that changing prices is costly. The rational expectations equilibrium of an economy with many such firms is constructed. It is shown that in this economy nominal shocks have a persistent effect on aggregate output. Furthermore, the real wage is demonstrated to move procyclically in such an economy.

Smith and Zimmerman [1976] suggested valuing employee stock options at the difference between the market price of the stock at the grant date and the present value of the exercise price of a simple call option on the stock discounted from the expiration date.' They also discussed modifications to this value to take account of the impact of dividends, differing income tax rates, and the problem of differential underdiversification across option holders. The purpose of this note is to extend the minimum value method by incorporating (a) random exercise prices which depend on stock prices, (b) fixed exercise price changes, and (c) ceilings on the amount of stock appreciation permitted in these awards. The minimum values which incorporate the first two extensions are obtained from the option models of Fischer [1978] and Merton [1973]. We derive the minimum value for the third extension from probability theory results for first-passage times for stochastic processes.

In this paper we analyze the solutions of linear econometric models with rational expectations. More precisely, we describe in detail the set of all the solutions; in particular this set is shown to be much larger than the sets previously considered. We also study various criteria of selection in this set of solutions and we examine to what extent these criteria redtiuce the set of the solutions.

We develop a model in which each firm chooses a hiring standard as well as a wage schedule and an application fee, we then characterize the set of Nash equilibria, and establish necessary and sufficient conditions for the existence of equilibrium. If the distribution of productivities within each ability type is Gaussian, workers who pass the test will be paid more than the value of their marginal product, while workers who fail the test will receive a wage, net of the application fee, below the value of their marginal product.