中老年人健康状况与家庭资产配置——基于资产流动性的视角

Health Status of the Middle-aged and Elderly and Household Asset Allocation:Portfolio Choice with Liquid and Illiquid Assets

本文从理论和实证两个方面研究了中老年人健康状况对于家庭流动性风险资产和非流动性风险资产投资决策的影响。一方面,疾病带来的医疗成本增加和规划周期缩短将带来两种资产的下降。另一方面,健康状况的下降增大了对于未来资金流动性的需求又会使得流动性资产回升,非流动性资产下降。在两种效应的共同作用下,流动性资产受健康的影响相对较小,非流动性资产所受影响则相对较大。基于中国健康与养老追踪(CHARLS)调查数据的实证分析也表明,健康状况较差的家庭对于投资性房产的持有显著低于健康状况好的家庭,而同样的结论在流动性风险资产持有上的显著性和稳健性则相对较弱。

Health risk is one of the most important background risks and may exert a significantly influence on an individual's wealth accumulation and well-being.The negative shock of disease brings about higher demand for liquidity and changes people's attitude toward asset liquidity and their investment psychology.How does health status affect Chinese households'portfolio choice regarding liquid and illiquid risky assets?What are the primary determinants of the observed patterns?This paper attempts to answer these questions within a unified framework.We build a continuous-time optimal consumption and portfolio choice model based on Merton's seminal work in which both liquid and illiquid risky assets are available for trading and investors are exposed to health risks.Trading a liquid asset incurs no transaction costs,so its purchase and sell prices are exactly the same.However,there is a bid-ask spread for the illiquid asset,where the spread is proportional to the purchase price.Our analysis shows that a household should focus not only on the absolute value of its liquid and illiquid wealth,but also on their relative magnitude.When the wealth of the illiquid asset account is too high relative to the wealth of the liquid asset account,the household should increase its holding in liquid assets and decrease its holding in illiquid assets.Conversely,when illiquid asset holdings are too low relative to liquid asset holdings,the household should reduce liquid assets and increase illiquid assets.When the ratio is in a medium range,the household should not adjust its illiquid assets holding.An investor is healthy at first but over time will become irreversibly unhealthy.An unhealthy investor receives less labor income,but his healthcare expenditure increases,which should be drawn from liquid wealth account.Worsening health also shortens an investor's planning horizon.These two forces lead to the following two testable implications:(1)a change in health status exerts a large impact on the household's holdings of illiquid assets,but(2)its impact on the household's holdings of liquid assets is ambiguous.We use survey data from the China Health and Retirement Longitudinal Study(CHARLS)2011-2015 to test the model's implications.Our empirical evidence confirms that households with bad health status tend to choose significantly lower holdings in investment housing than those with good health status.Our exploration reveals that this effect is mediated by a precautionary saving motive and the expectation of a shortened life span consistent with the model.When the explanatory variable is replaced by the holding of liquid risky assets,the result still holds but exhibits much weaker significance and robustness.Finally,we conduct some robustness checks.We use whether an individual has suffered from an accident or other unexpected,severe injury as an instrumental variable to solve the endogeneity problem.We also find that the policy intervention of home buying restrictions in a subset of cities does not affect our main results.The paper provides several policy implications.According to modern finance theory,in a complete market with sufficient financial tools,health risk as a typical idiosyncratic(negative)shock could be diversified to a large degree such that its impact on an individual's consumption and asset allocation will be limited.However,our findings are far from this ideal outcome.The fundamental approach to eradicate poverty caused by illness is to improve the public health system and promote investment in social health.Further development of the financial market also matters;for example,the design of well-priced insurance products with stable yields that meet households'needs merits further research.In addition,financial intermediaries should collaborate with medical institutions to provide loans to suffering households using housing as collateral.Finally,the development of the digital economy and“Internet+technology”will facilitate the organization of social resources to help families in need via crowd-funding platforms.