PORTFOLIO CHOICES,CONSUMPTION, AND PRICES IN A MARKET WITH DURABLE ASSETS

Recent research in investments has focused almost exclusively on financial assets such as corporate stocks. Although durable assets constitute an important part of investors' holdings, little effort has been made to explore their role in individuals' investments decisions and on assets pricing. This paper establishes results concerning the role of durable assets in the determination of optimum portfolio choices. The paper explores the effect of consumption considerations related to the service flows generated by durable assets on optimum portfolio considerations and asset prices. The main result is tied to the existence, or lack thereof, of efficient rental markets. In the absence of rental markets (or with restrictions on renting), investors' portfolio choices are not independent of consumption considerations as they are assumed to be in the standard CAPM. Individuals may thus hold different portfolios, and prices reflect the owner's inability to trade consumption flows. Under perfect market assumptions with unrestricted rental markets, optimum portfolio choices are undistinguishable from those implied by the standard CAPM in the sense that they are mean-variance efficient and identical for all individuals. Consumption is adjusted by trading service flows in the rental market. Prices, and the price of risk, however, reflect the existence of durable assets service flows as well as the risks involved in trading these flows in the rental market. In the model, risky rental income is introduced by uncertain rental costs. Equilibrium rental rates, an important part of the return expected from holding durable assets, are determined in the context of the mean-variance framework as a function of return and undiversifiable risk.     

On the distribution and estimation of trading costs

This paper investigates the uncertainty about the trading costs associated with a given portfolio strategy. I derive accurate approximations of the ex ante probability distributions of proportional trading costs and portfolio turnover under the conventional assumption of normal asset returns. Based on these approximations, I express the expected trading costs as a function of asset and portfolio characteristics. All else equal, the expected trading costs increase with: i) the deviations of the expected asset returns from the expected portfolio return, ii) the assets' volatility and iii) the portfolio volatility. At the same time, they decrease with the covariance between the assets and the portfolio. Furthermore, I propose novel estimators of the expected turnover and trading costs and show that they offer small bias and low variance, even when the sample size is small. Finally, I incorporate my results into a portfolio selection framework to produce portfolios with low levels of risk and trading costs. Several experiments with real and simulated data confirm the practical value of the results.     

Liquidity: Considerations of a Portfolio Manager

This paper examines liquidity and how it affects the behavior of portfolio managers, who account for a significant portion of trading in many assets. We define an asset to be perfectly liquid if a portfolio manager can trade the quantity she desires when she desires at a price not worse than the uninformed expected value. A portfolio manager is limited by both what she needs to attain and the ease with which she can attain it, making her sensitive to three dimensions of liquidity: price, timing, and quantity. Deviations from perfect liquidity in any of these dimensions impose shadow costs on the portfolio manager. By focusing on the trade-off between sacrificing on price and quantity instead of the canonical price-time trade-off, the model yields several novel empirical implications. Understanding a portfolio manager's liquidity considerations provides important insights into the liquidity of many assets and asset classes.     

基于期权平价原理的内幕交易管制设计

根据期权平价原理,股票、零息国债、欧式股票的买权与卖权等四类资产之间存在一种等价关系,因此每种资产都可由其他三个变量的投资组合来进行等价的表达。某些高管人员利用政府对分属于不同领域的投资组合的管制差异,以等价的期权投资组合替代股票交易从而进行变相内幕交易。中国证券监管部门有必要对管制制度安排进行优化,将衍生证券交易也纳入到内幕交易管制系统中来。     

Precautionary Savings with Risky Assets: When Cash Is Not Cash

U.S. industrial firms invest heavily in noncash, risky financial assets such as corporate debt, equity, and mortgage‐backed securities. Risky assets represent 40% of firms’ financial portfolios, or 6% of total book assets. We present a formal model to assess the optimality of this behavior. Consistent with the model, risky assets are concentrated in financially unconstrained firms holding large financial portfolios, are held by poorly governed firms, and are discounted by 13% to 22% compared to safe assets. We conclude that this activity represents an unregulated asset management industry of more than $1.5 trillion, questioning the traditional boundaries of nonfinancial firms.     

Relative risk aversion once more: An analysis of Japanese households' financial asset holding pattern

It is widely accepted that as the total assets increse, households tend to diversify their portfolios. In other words, absolute risk aversion is decreasing. On the other hand, the proportion of risky assets may increase or decrease depending on whether relative risk aversion (RRA) is decreasing or increasing, and its direction is still left open as an empirical question. This study examines the constancy of RRA from Japanese individual households' financial asset holding data collected in 1984. Constant RRA implies that the proportion of risky assets in one's portfolio is constant regardless of the amount of total assets. A casual observation of household portfolio holding pattern suggests that this implication is clearly violated by the data, because there are substantial proportion of households which do not hold any risky assets. Zero-holding, however, may be interpreted as a result of fixed transaction cost incurred by individual investors when they hold risky assets. Then, we pose a question, ‘Do investors hold constant proportion of risky assets, when they decide to hold them?’ In order to explain a substantial number of zero risky asset holders in the sample, we propose a portfolio selection model with a transaction cost, and estimate the model using a variant of Heckman's two-step method. In estimation we control for individual investors' socioeconomic characteristics, as well as income and total assets. The construction of the model imposes nonlinear restrictions on the two estimators, from which we can test the specification of the model. The estimation results suggest that there is a statistically significant decreasing tendency linked to total assets but that its rate of change tapers off as total assets increase. Our results are consistent with the previous studies which tended to support constant RRA for the higher asset holders, and complement previous studies in explaining lower asset holders' investment behavior.     

互联网金融资产的多目标投资组合研究

互联网金融的快速发展和不断创新,正在悄然改变着公众的投资理财行为。本文在分析互联网金融创新下公众流动性偏好、投资行为变化与资产选择的基础上,构建基于CRRA(常数相对风险厌恶)期末财富期望效用最大化和VaR最小化的多目标投资组合模型。同时引入多目标优化的NSGA-Ⅱ遗传算法,并选择实际数据对模型进行求解,得出最优的互联网金融资产组合。研究表明:(1)互联网金融给传统金融业带来冲击的同时,也改变了人们的流动性偏好、投资行为和资产组合选择。(2)互联网金融在一定程度上调和了金融资产“流动性、收益性和安全性”之间的矛盾,并兼顾了“三性”的相对统一。(3)模型求解结果显示,投资者对互联网金融资产的投资组合为低风险类资产60%左右、高风险类资产40%左右。     

动态不完全市场中不流动资产的定价

流动性对资产收益有重大影响,流动性好坏与资产能否流动是不同层面的问题,前者属于完全市场,后者属于不完全市场,但经典的金融经济学主要研究完全市场上的资产定价和最优组合策略。本文基于中国的现实制度背景,考察流动性受限对资产定价的影响,构建了动态不完全市场中不流动资产的定价模型及最优组合策略;证明了不流动性资产从根本上影响了最优组合策略,不流动资产折价率受到流动约束的时间长短、不流动资产收益的波动率等诸多参数的显著影响。     

A model for tax advantages of portfolios with many assets

Taxable portfolios present challenges for optimization models with even a limited number of assets. Holding many assets, however, has a distinct tax advantage over holding few assets. In this paper, we develop a model that takes an extreme view of a portfolio as a continuum of assets to gain the broadest possible advantage from holding many assets. We find the optimal strategy for trading in this portfolio in the absence of transaction costs and develop bounding approximations on the optimal value. We compare the results in a simulation study to a portfolio consisting only of a market index and show that the multi-asset portfolio’s tax advantage can lead either to significant consumption or bequest increases.     

Optimal Hedging and Valuation of Nontraded Assets

This paper examines a number of valuation problems faced byan expected-utility maximizing investor who, over a given timehorizon, is constrained to hold an asset which cannot be replicatedby dynamic trading and which therefore does not have a uniqueno-arbitrage price. We first derive the private valuation whichthe investor assigns to the nontraded asset in order to determinehis optimal investment in the traded assets. We thereby showthat, as part of this portfolio, the investor hedges the privatevaluation process of the nontraded asset, rather than its marketprice process. We also study the price at which the investorwould be willing to sell the nontraded asset if he were subsequentlyprohibited from trading in it, as well as the amount the investorwould be willing to pay to remove the trading restriction. Allthree values are shown to depend in an intuitive manner on theinvestor’s risk aversion, the residual risk of the nontradedasset unhedged by the traded assets, the difference betweenthe constrained holding and optimal unconstrained holding ofthe asset and the length of the time horizon over which theasset cannot be traded. JEL Classification: G11     

Semiparametric estimation of multi-asset portfolio tail risk

When correlations between assets turn positive, multi-asset portfolios can become riskier than single assets. This article presents the estimation of tail risk at very high quantiles using a semiparametric estimator which is particularly suitable for portfolios with a large number of assets. The estimator captures simultaneously the information contained in each individual asset return that composes the portfolio, and the interrelation between assets. Noticeably, the accuracy of the estimates does not deteriorate when the number of assets in the portfolio increases. The implementation is as easy for a large number of assets as it is for a small number. We estimate the probability distribution of large losses for the American stock market considering portfolios with ten, fifty and one hundred assets of stocks with different market capitalization. In either case, the approximation for the portfolio tail risk is very accurate. We compare our results with well known benchmark models.     

Portfolio rebalancing and the transmission of large-scale asset purchase programs: Evidence from the Euro area

The European Central Bank's large-scale asset purchase program targeted safe assets, but also aimed to impact prices of risky assets. The mechanism for this is the “portfolio rebalancing channel”, where financial institutions’ portfolio decisions impact financial prices more broadly. We examine this mechanism using cross-sectional heterogeneity in how the financial portfolios of different sectors of the European economy were affected around the purchase program. We find evidence of rebalancing. In vulnerable countries, where macroeconomic unbalances and relatively high risk premia remained, we document rebalancing towards riskier securities. In less vulnerable countries, based on granular information for large European banks, we document rebalancing toward bank loans.     

Talk and Action: What Individual Investors Say and What They Do

Combining survey responses and trading records of clients of a German retail broker, this paper examines some of the causes for the apparent failure to buy and hold a well-diversified portfolio. The subjective investor attributes gleaned from the survey help explain the variation in actual portfolio and trading choices. Self-reported risk aversion is the single most important determinant of both portfolio diversification and turnover; other things equal, investors who report being more risk tolerant hold less diversified portfolios and trade more aggressively. Less experienced investors similarly tend to churn poorly diversified portfolios. The effect of perceived knowledge on portfolio choice is less clear cut; holding other attributes constant, investors who think themselves knowledgeable about financial securities indeed hold better diversified portfolios, but those who think themselves more knowledgeable than the average investor churn their portfolios more. We thank Carol Bertaut, Anne Dorn, Larry Glosten, Will Goetzmann, Charles Himmelberg, Wei Jiang, Alexander Ljungqvist, Theo Nijman, Paul Sengmüller, Ralph Walkling, Elke Weber, and participants at the 2003 European Finance Association meetings in Glasgow for their comments.     

Optimal Hedging and Valuation of Nontraded Assets

This paper examines a number of valuation problems faced by an expected-utility-maximizing investor who, over a given time horizon, is constrained to hold an asset which cannot be replicated by dynamic trading and which therefore does not have a unique no-arbitrage price. We first derive the private valuation which the investor assigns to the nontradedasset in order to determine his optimal investment in the traded assets. We thereby show that, as part of this portfolio, the investor hedges the private valuation process of the nontraded asset, rather than its market price process. We also study the price at which the investor would be willing to sell the nontraded asset if he were subsequently prohibited from trading in it, as well as the amount the investor would be willing to pay to removethe trading restriction. All three values are shown to depend in an intuitive manner on the investor's risk aversion, the residual risk of the nontraded asset unhedged by the traded assets, the difference between the constrained holding and optimal unconstrained holding of the asset and the length of the time horizon over which the asset cannot be traded.     

Flight to liquidity and the Great Recession

This paper argues that counter-cyclical liquidity hoarding by financial intermediaries may strongly amplify business cycles. It develops a dynamic stochastic general equilibrium model in which banks operate subject to agency problems and funding liquidity risk in their intermediation activity. Importantly, the amount of liquidity reserves held in the financial sector is determined endogenously: Balance sheet constraints force banks to trade off insurance against funding outflows with loan scale. A financial crisis, simulated as an abrupt decline in the collateral value of bank assets, triggers a flight to liquidity, which strongly amplifies the initial shock and induces credit crunch dynamics sharing key features with the Great Recession. The paper thus develops a new balance sheet channel of shock transmission that works through the composition of banks’ asset portfolios.     

New strategies and a new paradigm for Shariah-compliant portfolio optimization

In this paper we analyze the effects of different strategies to construct Shariah compatible financial portfolios. The difference between conventional and current Shariah portfolio management is the application of sector screens and financial screens by which the asset universe is reduced. Yet, here different schools of scholars define different screening rules leading to significant differences with respect to compliance, but also with respect to performance. After analyzing this discrepancy we propose several new strategies to apply the inconsistent rule systems and a new paradigm for defining Shariah-compliance. Under this new paradigm compliance is attributed to the portfolio and not to the individual assets of the universe. We report results of an empirical study analyzing the potentials of these strategies and of the paradigm. We can show that under the proposed concepts Shariah-compliant portfolios can be realized which have return and risk profiles comparable to the conventional non-constrained portfolios.     

Dynamic Portfolio Selection by Augmenting the Asset Space

We present a novel approach to dynamic portfolio selection that is as easy to implement as the static Markowitz paradigm. We expand the set of assets to include mechanically managed portfolios and optimize statically in this extended asset space. We consider “conditional” portfolios, which invest in each asset an amount proportional to conditioning variables, and “timing” portfolios, which invest in each asset for a single period and in the risk‐free asset for all other periods. The static choice of these managed portfolios represents a dynamic strategy that closely approximates the optimal dynamic strategy for horizons up to 5 years.     

Investment beliefs of endowments

United States university and college endowments now hold close to one‐third of their portfolios in private equity and hedge funds. We estimate the implied beliefs of endowments on these alternative assets’ returns relative to equities and bonds. At the end of 2012, the typical endowment believes that its private equity investments will outperform a portfolio of conventional assets by 3.9% per year, and hedge funds will outperform by 0.7% per year. Taking into account the implied equity exposures in alternative asset positions, the effective equity holding of endowments is approximately 60%.     

Portfolio Choice in the Presence of Personal Illiquid Projects

Personal projects, such as a private business or the purchase of a home, influence individuals' portfolio choice. We conduct a theoretical analysis of this influence when financial assets are required to provide liquidity to personal projects. Due to this liquidity consideration, individuals behave in a more risk-averse fashion when there is a large penalty for discontinuing or underinvesting in the final stages of the projects. In addition, using data from the 1995 Survey of Consumer Finances, we find that households that are saving to invest in their own businesses or in their own homes indeed have significantly safer financial portfolios.     

Financial Literacy and Portfolio Dynamics

We match administrative panel data on portfolio choices with survey measures of financial literacy. When we control for portfolio risk, the most literate households experience 0.4% higher annual returns than the least literate households. Distinct portfolio dynamics are the key determinant of this difference. More literate households hold riskier positions when expected returns are higher, they more actively rebalance their portfolios and do so in a way that holds their risk exposure relatively constant over time, and they are more likely to buy assets that provide higher returns than the assets that they sell.