Dollar Cost Averaging Research Articles

Autocorrelated Returns and Optimal Intertemporal Portfolio Choice

In recent years it has been shown empirically that stock returns exhibit positive or negative autocorrelation, depending on observation frequency. In this context of autocorrelated returns the present paper is the first to derive an explicit analytical solution to the dynamic portfolio problem of an individual agent saving for retirement (or other change of status, like the purchase of a house or starting college). Using a normal ARMA(1,1) process, dynamic programming techniques combined with the use of Stein's Lemma are employed to examine “dollar-cost-averaging” and “age effects” in intertemporal portfolio choice with CARA preferences. We show that with a positive moving average parameter and positive riskfree rates, if first-order serial correlation is nonnegative, then the expected value of the optimal risky investment is increasing over time, while if first-order serial correlation is negative this path can be increasing or decreasing over time. Thus a necessary but not sufficient condition to obtain the conventional age effect of increasing conservatism over time is that first-order serial correlation be negative. Further, dollar-cost averaging in the general sense of gradual entry into the risky asset does not emerge as an optimal policy. Simulation results for U.S. data are used to illustrate optimal portfolio paths.

Nobody Gains from Dollar Cost Averaging Analytical, Numerical and Empirical Results


 
 
 Dollar Cost Avemging is an investment system that is widely advocated by brokerage firms and mutual funds. In its best known form, an investor seeking to put a lump sum into risky assets is counseled to invest the money over a period of time in equal installments in or&r to avoid the devastating effect of a marketfall immediately afkr a single, lump-sum investment. Using graphical analysis, historical stock market returns, and Monte Carlo simulations, this article demonstmtes that no such benefit accrues to a Dollar Cost Averaging Stmtegy. Two alternative strategies, optimal rebalancing and buy and hold achieve better performance in all three analyses.
 
 

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 one's 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.