ESSAYS ON PORTFOLIO CHOICE AND HEALTH OVER THE LIFE CYCLE

Abstract

This dissertation examines the effect of health and its associated variables on households' consumption and portfolio choices over life cycle. The first two essays constitute my job market paper, which explains why the risky portfolio share rises in wealth from two health mechanisms: endogenous health investment and medical expenditure risk. The third chapter explores the effect of health and health risk on households' optimal consumption and portfolio decisions over life cycle. Chapter 1 titled ``PORTFOLIO CHOICE AND HEALTH ACROSS WEALTH: EMPIRICAL EVIDENCE" illustrates the empirical relationship between the portfolio puzzle and the heterogeneity of health variables across wealth. Classic financial theory suggests that under the assumption of no borrowing constraints and no mean-reverting stock returns, households should hold a constant risky portfolio in spite of their wealth, ages and life horizons (Samuelson (1969) and Merton (1969, 1971)). Yet data from the Survey of Consumers Finances (SCF) show that the risky portfolio share of financial assets increases in wealth. In the literature, this is called the ``portfolio puzzle". Meanwhile, various sources of data indicate that, compared with the non-wealthy households, the wealthy people have better health, longer life horizon, higher out of pocket medical spending with lower uncertainty, and more health care time. All these facts suggest a novel correlation between the portfolio puzzle and the heterogeneity of health variables across wealth and provide a robust empirical foundation to explain the portfolio puzzle from a health perspective. In Chapter 2 titled ``A LIFE CYCLE MODEL OF PORTFOLIO CHOICE AND HEALTH", a life cycle model with endogenous health investment and medical expenditure risk is proposed to capture the key empirical features in the first chapter. This calibrated model remarkably matches the U.S. data. I find that endogenous health investment is essential to explain the portfolio puzzle: if health is exogenous without investment, the model can only could deliver 7.2% of the risky share gap across wealth. Medical expenditure risk is less important and has a larger effect on the non-wealthy group. If I abstract from medical expenditure risk, the risky shares increase for both groups: 24% for the low wealth group and 5% for the wealthy group. This life cycle model provides new insights into how health affects households' financial behavior. Chapter 3 titled ``OPTIMAL CONSUMPTION AND PORTFOLIO CHOICE WITH HEALTH RISK" investigates the effect of health and health risk on households' optimal consumption and portfolio allocations over the life cycle. The simulation results show that consumption, savings in bonds, and savings in stocks all increase with health. The risky portfolio share, which is the ratio of savings in stocks to the total financial assets, demonstrates the same tendency for both health states over the life cycle: at the very young age, the risky portfolio share is relatively high. Starting from the middle age, this share falls significantly and keeps steady until the end of life. For most of the lifetime, the risky portfolio share is positively related with health. These results emphasize the importance of health and its associated risk in consumption and portfolio decisions.