George M. Constantinides

Habit Formation: A Resolution of the Equity Premium Puzzle

The equity premium puzzle, identified by Mehra and Prescott, states that, for plausible values of the risk aversion coefficient, the difference of the expected rate of return on the stock market and the riskless rate of interest is too large, given the observed small variance of the growth rate in per capita consumption. The puzzle is resolved in the context of an economy with rational expectations once the time separability of von Neumann-Morgenstern preferences is relaxed to allow for adjacent complementarity in consumption, a property known as habit persistence. Essentially habit persistence drives a wedge between the relative risk aversion of the representative agent and the intertemporal elasticity of substitution in consumption.

Junior Can't Borrow: A New Perspective on the Equity Premium Puzzle

Ongoing questions on the historical mean and standard deviation of the return on equities and bonds and on the equilibrium demand for these securities are addressed in the context of a stationary, overlapping-generations economy in which consumers are subject to a borrowing constraint. The key feature captured by the OLG economy is that the bulk of the future income of the young agents is derived from their wages forthcoming in their middle age, while the bulk of the future income of the middle-aged agents is derived from their savings in equity and bonds. The young would like to borrow and invest in equity, but the borrowing constraint prevents them from doing so. The middle-aged choose to hold a diversified portfolio that includes positive holdings of bonds, and this explains the demand for bonds. Without the borrowing constraint, the young borrow and invest in equity, thereby decreasing the mean equity premium and increasing the rate of interest.

Bounds on prices of contingent claims in an intertemporal economy with proportional transaction costs and general preferences

Abstract. Analytic bounds on the reservation write price of European-style contingent claims are derived in the presence of proportional transaction costs in a model which allows for intermediate trading. The option prices are obtained via a utility maximization approach by comparing the maximized utilities with and without the contingent claim. The mathematical tools come mainly from the theories of singular stochastic control and viscosity solutions of nonlinear partial differential equations.

Warrant exercise and bond conversion in competitive markets

Abstract We develop a theory of warrants held by competitive warrantholders not constrained to exercise their warrants as one block; the theory also applies to convertible bonds held by competitive bondholders not constrained to convert their bonds as one block. We prove that the warrant (bond) price in each of the competitive equilibria is less than or equal to the price in an economy with the block constraint; and for at least one competitive equilibrium the warrant (bond) price equals the warrant (bond) price in the block-constrained economy. We illustrate the paths of competitive warrant exercise and bond conversion and conclude that under realistic assumptions they can be long.

Admissible uncertainty in the intertemporal asset pricing model

Abstract We embed the Sharpe-Lintner, two-parameter asset pricing theory in an intertemporal general equilibrium model. The investment opportunity set changes stochastically over time; in general the short-term and long-term interest rates and the distribution of the rate of return of the market portfolio are non-stationary. This non-stationarity, which is admissible in the Sharpe-Lintner model, has two implications: First, it may bias econometric methods which fail to explicitly take into account the non-stationarity. Second, the sequential application of the Sharpe-Lintner model in the discounting of stochastic cash flows becomes computationally complex and of little practical use.

Bounds on Derivative Prices in an Intertemporal Setting with Proportional Transaction Costs and Multiple Securities

The observed discrepancies of derivative prices from their theoretical, arbitrage-free values are examined in the presence of proportional transaction costs. Analytic upper and lower bounds on the reservation write and purchase prices, respectively, are obtained when an investors preferences exhibit constant relative risk aversion between zero and one. The economy consists of multiple primary securities with the stationary returns, a constant rate of interest, and any number of American or European derivatives with path-dependent arbitrary payoffs. The price processes of the primary securities are modelled either as jump/diffusions in a continuous-time framework, or as arbitrary processes in a discrete-time framework.

Stochastic dominance bounds on derivatives prices in a multiperiod economy with proportional transaction costs

By applying stochastic dominance arguments, upper bounds on the reservation write price of European calls and puts and lower bounds on the reservation purchase price of these derivatives are derived in the presence of proportional transaction costs incurred in trading the underlying security. The primary contribution is the derivation of bounds when intermediate trading in the underlying security is allowed over the life of the option. A tight upper bound is derived on the reservation write price of a call and a tight lower bound is derived on the reservation purchase price of a put. These results jointly impose tight upper and lower bounds on the implied volatility.

A Note on the Suboptimality of Dollar-Cost Averaging as an Investment Policy

The widespread notion that dollar-cost averaging can help an investor minimize the risk of investing all of ones capital in the market at an inappropriate time is aptly stated by Malkiel [4, p. 242]:Periodic investments of equal dollar amounts in common stocks can substantially reduce (but not avoid) the risks of equity investment by insuring that the entire portfolio of stocks will not be purchased at temporarily inflated prices. The investor who makes equal dollar investments will buy fewer shares when prices are high and more shares when prices are low.

Strategic analysis of the competitive exercise of certain financial options

Abstract Warrants and convertible bonds are claims on the firm which change the outstanding number of common stock shares when exercised or converted. Exercise of such claims in competitive circumstances is modeled here as a noncooperative game played by a continuum of players. First, equilibria of the game are shown to exist by applying results of Schmeidler. Second, the games equilibria are compared to outcomes that come about when one individual controls the exercise of all the claims, but is constrained to exercise them in one block. The results are analogues of earlier results by one of the authors on the competitive pricing of such claims.

Asset Pricing with Countercyclical Household Consumption Risk

We show that shocks to household consumption growth are negatively skewed, persistent, countercyclical, and drive asset prices. We construct a parsimonious model where heterogeneous households have recursive preferences. A single state variable drives the conditional cross-sectional moments of household consumption growth. The estimated model fits well the unconditional cross-sectional moments of household consumption growth and the moments of the risk-free rate, equity premium, price-dividend ratio, and aggregate dividend and consumption growth. The model-implied risk-free rate and price-dividend ratio are procyclical while the market return has countercyclical mean and variance. Finally, household consumption risk explains the cross-section of excess returns.