Predictability and Transaction Costs: The Impact on Rebalancing Rules and Behavior

We consider the impact of transaction costs on the portfolio decisions of a long-lived agent with isoelastic preferences. In particular, we focus on how portfolio choice, rebalancing frequency and average cost incurred change over the lifecycle are affected by return predictability. Two types of costs are evaluated: proportional to the change in the holding of the risky asset and a fixed fraction of portfolio value. We find that realistic transaction costs can materially affect rebalancing behavior, creating no-trade regions that widen near the investor's terminal date. At the same time, realistic proportional and fixed costs have little effect on the midpoint of the no-trade region, unless liquidation costs differ across assets. Return predictability calibrated to U.S. stock returns is found to have large effects on rebalancing behavior relative to independent and identically distributed (i.i.d.) returns with the same unconditional distribution. For example, return predictability causes rebalancing frequency to increase, and cost incurred to increase by an order of magnitude, at all points in the investor's life. No-trade regions early in life are wider when returns are predictable than when they are not. Finally, we find that the nature of the return predictability, including the presence or not of return heteroscedasticity, can have large effects on rebalancing behavior.