Investing Retirement Wealth: A Life-Cycle Model

If household portfolios are constrained by borrowing and short-sales restrictions asset markets, then alternative retirement savings systems may affect household welfare by relaxing these constraints. This paper uses a calibrated partial-equilibrium model of optimal life-cycle portfolio choice to explore the empirical relevance of these issues. In a benchmark case, we find ex-ante welfare gains equivalent to a 3.7% increase in consumption from the investment of half of retirement wealth in the equity market. The main channel through which these gains are realized is that the higher average return on equities permits a lower Social Security tax rate on younger households, which helps households smooth their consumption over the life cycle. There is a smaller welfare gain of 0.5% of consumption when Social Security tax rates are held constant. We also find that realistic heterogeneity of risk aversion and labor income risk can strongly affect optimal portfolio choice over the life cycle, which provides one argument for a privatized Social Security system with an element of personal portfolio choice.

Robustness and dynamic sentiment

Errors in survey expectations display waves of pessimism and optimism and significant sluggishness. This paper develops a novel theoretical framework of time-varying beliefs capturing these empirical characteristics. The dynamic beliefs arise endogenously due to agents’ attitude toward alternative models. Decision-maker’s distorted beliefs generate countercyclical risk aversion, procyclical portfolio weights, countercyclical equilibrium asset returns, and excess volatility. A calibrated version of our model is shown to match salient features in equity markets.Errors in survey expectations display waves of pessimism and optimism and significant sluggishness. This paper develops a novel theoretical framework of time-varying beliefs capturing these empirical facts. In our model, the dynamic beliefs arise endogenously due to agents’ attitude toward alternative models. Decision-maker’s distorted beliefs generate countercyclical risk aversion, procyclical portfolio weights, countercyclical equilibrium asset returns, and excess volatility. A calibrated version of our model is shown to match salient features in equity markets.https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3798445First author draf

Stock Market Mean Reversion and the Optimal Equity Allocation of a Long-Lived Investor

This paper solves numerically the intertemporal consumption and portfolio choice problem of an infinitely-lived investor who faces a time-varying equity premium. The solutions we obtain are very similar to the approximate analytical solutions of Campbell and Viceira (1999), except at the upper extreme of the state space where both the numerical consumption and portfolio rules flatten out. We also consider a constrained version of the problem in which the investor faces borrowing and short-sales restrictions. These constraints bind when the equity premium moves away from its mean in either direction, and are particularly severe for risk-tolerant investors. The constraints have substantial effects on optimal consumption, but much more modest effects on optimal portfolio choice in the region of the state space where they are not binding.Economic

Robust Portfolio Rules and Asset Pricing

I present a new approach to the dynamic portfolio and consumption problem of an investor who worries about model uncertainty (in addition to market risk) and seeks robust decisions along the lines of Anderson, Hansen, and Sargent (2002). In accordance with max-min expected utility, a robust investor insures against some endogenous worst case. I first show that robustness dramatically decreases the demand for equities and is observationally equivalent to recursive preferences when removing wealth effects. Unlike standard recursive preferences, however, robustness leads to environment-specific "effective" risk aversion. As an extension, I present a closed-form solution for the portfolio problem of a robust Duffie-Epstein-Zin investor. Finally, robustness increases the equilibrium equity premium and lowers the risk-free rate. Reasonable parameters generate a 4% to 6% equity premium. Copyright 2004, Oxford University Press.