Consumption and Portfolio Choice over the Life Cycle

This article solves a realistically calibrated life cycle modelof consumption and portfolio choice with non-tradable laborincome and borrowing constraints. Since labor income substitutesfor riskless asset holdings, the optimal share invested in equitiesis roughly decreasing over life. We compute a measure of theimportance of human capital for investment behavior. We findthat ignoring labor income generates large utility costs, whilethe cost of ignoring only its risk is an order of magnitudesmaller, except when we allow for a disastrous labor incomeshock. Moreover, we study the implications of introducing endogenousborrowing constraints in this incomplete-markets setting.     

Dynamic Consumption and Portfolio Choice with Stochastic Volatility in Incomplete Markets

This paper examines the optimal consumption and portfolio-choiceproblem of long-horizon investors who have access to a risklessasset with constant return and a risky asset ("stocks") withconstant expected return and time-varying precision—thereciprocal of volatility. Markets are incomplete, and investorshave recursive preferences defined over intermediate consumption.The paper obtains a solution to this problem which is exactfor investors with unit elasticity of intertemporal substitutionof consumption and approximate otherwise. The optimal portfoliodemand for stocks includes an intertemporal hedging componentthat is negative when investors have coefficients of relativerisk aversion larger than one, and the instantaneous correlationbetween volatility and stock returns is negative, as typicallyestimated from stock return data. Our estimates of the jointprocess for stock returns and precision (or volatility) usingU.S. data confirm this finding. But we also find that stockreturn volatility does not appear to be variable and persistentenough to generate large intertemporal hedging demands.     

A Simulation Approach to Dynamic Portfolio Choice with an Application to Learning About Return Predictability

We present a simulation-based method for solving discrete-timeportfolio choice problems involving non-standard preferences,a large number of assets with arbitrary return distribution,and, most importantly, a large number of state variables withpotentially path-dependent or non-stationary dynamics. The methodis flexible enough to accommodate intermediate consumption,portfolio constraints, parameter and model uncertainty, andlearning. We first establish the properties of the method forthe portfolio choice between a stock index and cash when thestock returns are either iid or predictable by the dividendyield. We then explore the problem of an investor who takesinto account the predictability of returns but is uncertainabout the parameters of the data generating process. The investorchooses the portfolio anticipating that future data realizationswill contain useful information to learn about the true parametervalues.     

Principles of Financial Regulation: A Dynamic Portfolio Approach

Economists seeking explanations for the global financial crisisof 1997–99 are reaching consensus that a major factorwas weak financial institutions, which resulted in part frominadequate government regulations. At the same time many developingcountries are struggling with an overregulated financial system—onethat stifles innovation and the flow of credit to new entrepreneursand that can stunt the growth of well-established firms. Inparticular, too many countries are relying excessively on capitaladequacy standards, which are inefficient and sometimes counterproductive.The author argues that financial systems can be reformed successfullyusing a "dynamic portfolio approach" aimed at managing the incentivesand constraints that affect not only financial institutions'exposure to risk but also their ability to cope with it. Thearticle sets out general principles of financial regulationand shows how the dynamic portfolio approach can help countriesdeal with the special problems that arise during the transitionto a more liberalized economy as well as those that arise indealing with a financial crisis similar to the 1997 crisis inEast Asia.      

Portfolio Optimization under Solvency Constraints: A Dynamical Approach

We develop portfolio optimization problems for a nonlife insurance company seeking to find the minimum capital required that simultaneously satisfies solvency and portfolio performance constraints. Motivated by standard insurance regulations, we consider solvency capital requirements based on three criteria: ruin probability, conditional Value-at-Risk, and expected policyholder deficit ratio. We propose a novel semiparametric formulation for each problem and explore the advantages of implementing this methodology over other potential approaches. When liabilities follow a Lognormal distribution, we provide sufficient conditions for convexity for each problem. Using different expected return on capital target levels, we construct efficient frontiers when portfolio assets are modeled with a special class of multivariate GARCH models. We find that the correlation between asset returns plays an important role in the behavior of the optimal capital required and the portfolio structure. The stability and out-of-sample performance of our optimal solutions are empirically tested with respect to both the solvency requirement and portfolio performance, through a double rolling window estimation exercise.     

Correlation Risk and Optimal Portfolio Choice

We develop a new framework for multivariate intertemporal portfolio choice that allows us to derive optimal portfolio implications for economies in which the degree of correlation across industries, countries, or asset classes is stochastic. Optimal portfolios include distinct hedging components against both stochastic volatility and correlation risk. We find that the hedging demand is typically larger than in univariate models, and it includes an economically significant covariance hedging component, which tends to increase with the persistence of variance–covariance shocks, the strength of leverage effects, the dimension of the investment opportunity set, and the presence of portfolio constraints.     

Systemic Risk and International Portfolio Choice

Returns on international equities are characterized by jumps; moreover, these jumps tend to occur at the same time across countries leading to systemic risk. We capture these stylized facts using a multivariate system of jump‐diffusion processes where the arrival of jumps is simultaneous across assets. We then determine an investor's optimal portfolio for this model of returns. Systemic risk has two effects: One, it reduces the gains from diversification and two, it penalizes investors for holding levered positions. We find that the loss resulting from diminished diversification is small, while that from holding very highly levered positions is large.     

Income Risk and Portfolio Choice: An Empirical Study

This paper investigates the relationship between portfolio choice and labor income risk in the National Longitudinal Survey of Youth 1979 Cohort. Permanent income risk (variability of shocks to income that have permanent effect) significantly reduces the share of risky assets in the household's portfolio, while transitory income risk (variability of shocks with no lasting effect) does not. This result provides strong evidence that households' portfolio choices respond to labor income risks in a manner consistent with economic theory.     

Hedging, Familiarity and Portfolio Choice

We exploit the restrictions of intertemporal portfolio choicein the presence of nonfinancial income risk to test hedgingusing the information contained in the actual portfolio of theinvestor. We use a unique data set of Swedish investors withinformation broken down at the investor level and into variouscomponents of investor wealth, income, and demographic characteristics.Portfolio holdings are identified at the stock level. We showthat investors do not hedge but invest in stocks closely relatedto their nonfinancial income. We explain this with familiarity,that is, the tendency to concentrate holdings in stocks to whichthe investor is geographically or professionally close or thathe has held for a long period. We show that familiarity is nota behavioral bias, but is information driven. Familiarity-basedinvestment allows investors to earn higher returns than theywould have otherwise earned if they had hedged.     

Portfolio Choice and Life Insurance: The CRRA Case

We solve a portfolio choice problem that includes life insurance and labor income under constant relative risk aversion (CRRA) preferences. We focus on the correlation between the dynamics of human capital and financial capital and model the utility of the family as opposed to separating consumption and bequest. We simplify the underlying Hamilton–Jacobi–Bellman equation using a similarity reduction technique that leads to an efficient numerical solution. Households for whom shocks to human capital are negatively correlated with shocks to financial capital should own more life insurance with greater equity/stock exposure. Life insurance hedges human capital and is insensitive to the family's risk aversion, consistent with practitioner guidance.     

Portfolio Capital Flows in Thailand: A Bayesian Model Averaging Approach

We study the gross and net terms of portfolio capital flows by examining their determinants. Through the application of the Bayesian model averaging method, the determinants are evaluated by a set of models instead of a single specification. Our findings show that the magnitude of both gross equity and gross debt flows are large, relative to their net terms. Equity inflows and outflows are quite symmetric with similar determinants; debt inflows and outflows are less symmetric. The paper provides partial evidence to support the importance of both internal and external factors as determinants of capital flows.     

A Factor Allocation Approach to Optimal Bond Portfolio

This paper proposes a new method to a bond portfolio problem in a multi-period setting. In particular, we apply a factor allocation approach to constructing the optimal bond portfolio in a class of multi-factor Gaussian yield curve models. In other words, we consider a bond portfolio problem in terms of a factors’ allocation problem. Thus, we can obtain clear interpretation about the relation between the change in the shape of a yield curve and dynamic optimal strategy, which is usually hard to be obtained due to high correlations among individual bonds. We first present a closed form solution of the optimal bond portfolio in a class of the multi-factor Gaussian term structure model. Then, we investigate the effects of various changes in the term structure on the optimal portfolio strategy through series of comparative statics.     

Wealth, Information Acquisition, and Portfolio Choice

I solve (with an approximation) a Grossman-Stiglitz economyunder general preferences, thus allowing for wealth effects.Because information generates increasing returns, decreasingabsolute risk aversion, in conjunction with the availabilityof costly information, is sufficient to explain why wealthierhouseholds invest a larger fraction of their wealth in riskyassets. One no longer needs to resort to decreasing relativerisk aversion, an empirically questionable assumption. Furthermore,I show how to distinguish empirically between these two explanations.Finally, I find that the availability of costly informationexacerbates wealth inequalities.     

A Benchmark Approach to Portfolio Optimization under Partial Information

This paper proposes a filtering methodology for portfolio optimization when some factors of the underlying model are only partially observed. The level of information is given by the observed quantities that are here supposed to be the primary securities and empirical log-price covariations. For a given level of information we determine the growth optimal portfolio, identify locally optimal portfolios that are located on a corresponding Markowitz efficient frontier and present an approach for expected utility maximization. We also present an expected utility indifference pricing approach under partial information for the pricing of nonreplicable contracts. This results in a real world pricing formula under partial information that turns out to be independent of the subjective utility of the investor and for which an equivalent risk neutral probability measure need not exist.      

Portfolio Choice and Asset Prices: The Importance of Entrepreneurial Risk

Using cross-sectional data from the SCF and Tax Model, we show that entrepreneurial income risk has a significant influence on portfolio choice and asset prices. We find that households with high and variable business income hold less wealth in stocks than other similarly wealthy households, although they constitute a significant fraction of the stockholding population. Similarly for nonentrepreneurs, holding stock in the firm where one works reduces the portfolio share of other common stocks. Finally, we show that adding proprietary income to a linear asset pricing model improves its performance over a similar model that includes only wage income.     

Strategic Interactions and Portfolio Choice in Money Management: Theory and Evidence

I study portfolio choice of strategic fund managers in the presence of a peer‐based underperformance penalty. While the penalty generates herding behavior, correlated trading among managers is exacerbated when a strategic setting is considered. The equilibrium portfolios are driven by the least restricted manager, who may vary according to the realization of returns. I compare model predictions to evidence from the Colombian pension fund management industry, where six asset managers are in charge of portfolio allocation for the mandatory contributions of the working population. These managers are subject to a peer‐based underperformance penalty, which is known as the minimum return guarantee (MRG). I study trading behavior by managers before and after a change in the strictness of the MRG in June 2007. The evidence suggests that a tighter MRG results in more trading in the direction of peers, a behavior that is more pronounced for underperforming managers. I show that these findings are consistent with the qualitative and quantitative predictions of the theoretical model.     

资源消耗与经济增长:一个动态面板数据方法

资源消耗与经济增长有着密不可分的关系。本文选取1985-2008年的数据,利用国际上研究资源消耗与经济增长之间关系的重要工具--面板协整分析、误差修正模型及面板格兰杰因果检验对中国省级层面资源消耗与经济增长之间的动态关系进行了研究。研究结果表明:资源消耗与经济增长之间存在长期双向因果关系。据此,提出了一些科学合理的经济发展和资源产业政策。     

Modeling the Conditional Covariance Between Stock and Bond Returns: A Multivariate GARCH Approach

To analyze the intertemporal interaction between the stock andbond market returns, we assume that the conditional covariancematrix follows a multivariate GARCH process. We allow for asymmetriceffects in conditional variances and covariances. Using dailydata, we find strong evidence of conditional heteroskedasticityin the covariance between stock and bond market returns. Theresults indicate that not only variances, but also covariancesrespond asymmetrically to return shocks. Bad news in the stockand bond market is typically followed by a higher conditionalcovariance than good news. Cross asymmetries, that is, asymmetriesfollowed from shocks of opposite signs, appear to be importantas well. Covariances between stock and bond returns tend tobe relatively low after bad news in the stock market and goodnews in the bond market. A financial application of our modelshows that optimal portfolio shares can be substantially affectedby asymmetries in covariances. Moreover, our results show sizablegains due to asymmetric volatility timing.