Knowledge that Transforms

This paper develops general overtaking techniques for studying the asymptotic properties of portfolio policies optimal with respect to a terminal utility valuation. For a restricted class of utility functions the sequence of optimal constant (non-revised) portfolio policies formed as the horizon recedes into the future is shown to converge. Furthermore, for utility functions unbounded above and below, this turnpike policy need not be the policy associated with the minimal constant relative risk aversion function that bounds the valuation function from above. Finally, an analogy between the portfolio turnpike problem and the turnpike problem of growth theory is studied.

This paper outlines models of capital market equilibrium when there are explicit barriers to international investment in the form of a tax on holdings of assets in one country by residents of another country. There is a corresponding subsidy on short positions in foreign assets. Asset prices deviate from the predictions of the world capital asset pricing model. Investors do not hold a mixture of national market portfolios, but the mix of risky assets is the same for every investor in a country. Optimal portfolios tend to be heavy in domestic assets, and light in foreign assets. Tax free investors, however, tend to hold assets anywhere in the world that are taxed heavily. Estimates of the magnitude of the average tax (or the magnitude of effective barriers to international investment) can be made by comparing the average return on the minimum variance zero β portfolio, z, with the average across countries and time of the short-term interest rate. When barriers are ineffective, the expected return on portfolio z will be the average short-term interest rate, and the world capital asset pricing model will hold.

This paper presents some of the implications of modern portfolio theory for the equilibrium structure of wages under conditions of uncertainty. The primary model presented is a model of wage uncertainty and hence the equilibrium structure is derived in terms of expected wages. The equilibrium structure with the assumption of a perfect labor market (e.g., labor units are infinitely divisible and costlessly mobile) and a perfect capital market is shown to have a very simple linear form. The model assumes homogeneous labor units as well as the usual single-period capital asset pricing model assumptions.

This paper suggests that it is not possible to demonstrate, using the best available empirical methods, that the expected returns on high yield common stocks differ from the expected returns on low yield common stocks either before or after taxes. A taxable investor who concentrates his portfolio in low yield securities cannot tell from the data whether he is increasing or decreasing his expected after-tax return by so doing. A tax exempt investor who concentrates his portfolio in high yield securities cannot tell from the data whether he is increasing or decreasing his expected return. We argue that the best method for testing the effects of dividend policy on stock prices is to test the effects of dividend yield on stock returns. Thus the fact that we cannot tell, using the best available methods, what effects dividend yield has on stock returns implies that we cannot tell what effect, if any, a change in dividend policy will have on a corporation's stock price.

This paper considers the problem of the investor who has numerous opportunities for revising his portfolio and whose choices are governed by a utility function defined on ‘terminal’ wealth, U0(x0). Attention is focussed on the behavior of the induced utility functions of intermediate wealth with n periods to go, Un(xn), and the associated investment policies. Conditions under which the functions Un(xn) will tend to isoelasticity have previously been given by Mossin and by Leland. In this paper, the conditions for convergence are weakened further, to the point where they appear sufficiently broad to encompass perhaps most utility functions of practical interest.

In this article, the quantitative form of capital market equilibrium is derived for a multi-period economy in which (a) there are many consumption goods whose future prices are uncertain, and (b) the investment opportunities available to consumers include both common stocks and default-free bills of many different maturities. Particular emphasis is placed on consumer reaction to uncertainty about shifts in commodity prices and the term structure of interest rates and on the way one should expect to observe this reaction reflected in portfolio choices and equilibrium stock prices.

The purpose of this paper is to note that the question of optimal diversification cannot be answered simply by determining the average variability of equally allocated investment. Empirical results are presented which show that it is possible to obtain the same level of average variation with far greater average portfolio returns and fewer securities in the portfolio by using an alternative allocation scheme.