Portfolio Underdiversification Research Articles

Flight to quality and portfolio diversification under ambiguity of correlation

We argue that ambiguous correlation between asset payoffs plays an important role in the occurrence of “flight to quality”, which in some circumstances leads investors with incomplete information to portfolio under-diversification. In this paper, we consider a multi-asset economy with four types of investors who have heterogeneous beliefs on correlation coefficients, and in which ambiguity-averse traders make decisions in a maxmin expected utility framework. A unique general equilibrium presents in four scenarios according to the dispersion of asset quality. We define a measure to gauge the degree of portfolio under-diversification, with which we show that correlation ambiguity will drive less-informed investors to hold a nondiversified portfolio if the correlation coefficient is negative, while a positive correlation drives some less-informed investors to hold a fully diversified portfolio.

Determinants of idiosyncratic risk: evidence from BRICS countries

PurposeThis study examines the determinants of idiosyncratic risk (IR) or unsystematic risk. The study also examines the determinants of IR by dividing the firms into different categories: beta-based firms, liquid and illiquid firms and financially constrained (FC) and unconstrained (FUC) firms.Design/methodology/approachThe fixed effects static panel data model specifications are formulated based on Hausman (1978) test for BRICS (Brazil, Russia, India, China, and South Africa) member countries over the period 2000–2019. Moreover, the t-test is applied to see whether the returns of different types of portfolios are significantly different.FindingsThe portfolio analysis results show that, on average, high IR firms tend to be small in size, highly leveraged, have low competitiveness, low profitability, less dividend yield and low returns for all the sampled countries. The sample paired t-test also confirms that a significant difference exists between extreme portfolios: small and large size and low IR and high IR portfolios. The panel regression results show that firm size, market power, price-to-earnings ratio, return on equity (ROE) and dividend yield negatively relates to IR. Yet, both leverage and liquidity are positively related to IR. However, the sign of momentum returns is mostly positive for the entire sample. The coefficient values for high-beta, FC and illiquid firms are more significant and large than the firms' counterparts for all BRICS member countries. These results support the hypothesis of an under-diversified portfolio and suggest that the above-mentioned firm-specific variables are the significant determinants of unsystematic risk.Practical implicationsThe securities exchange commission, as the supervisor of the public limited companies, needs to increase its role in investor protection related to the uncertainty of investment in the capital market. Accordingly, in making investment decisions in a stock exchange, investors can use the information that captures unsystematic risk for investment decision-making.Originality/valueThis study is the first to explore the determinants of IR in top emerging countries. Second, none of the existing studies has focused on the determinants of the IR based on different categories of firms.

The Short-Run and Long-Run Components of Idiosyncratic Volatility and Stock Returns

To capture the dynamics of idiosyncratic volatility of stock returns over different horizons and investigate the relationship between idiosyncratic volatility and expected stock returns, this paper develops and estimates a parsimonious model of idiosyncratic volatility consisting of a short-run and a long-run component. The conditional short-run and long-run components are found to be positively and negatively related to expected stock returns, respectively. The positive relation between the short-run component and stock returns may be caused by investors requiring compensation for bearing idiosyncratic volatility risk when facing trading frictions and hold underdiversified portfolios. The negative relationship between the long-run component and stock returns may reflect the fact that stocks with high long-run idiosyncratic volatility are less exposed to systematic risk factors and, hence, earn lower returns. Moreover, the low-risk exposure of stocks characterized by high idiosyncratic volatility lends support to real-option-based mechanisms to explain this negative relation. In particular, the systematic risk of a firm with abundant growth options crucially depends upon the risk exposure of these options. The value of growth options could rise significantly because of convexity when the increase in idiosyncratic volatility occurs over long horizons. And growth options’ systematic risk could fall because the relative magnitude of their value in relation to systematic risk factors decreases.This paper was accepted by David Simchi-Levi, finance.

Household Portfolio Underdiversification and Probability Weighting: Evidence from the Field

AbstractWe test whether probability weighting affects household portfolio choice in a representative survey. On average, people display inverse-S-shaped probability weighting, overweighting low probability events. As theory predicts, probability weighting is positively associated with portfolio underdiversification and significant Sharpe ratio losses. Analyzing respondents’ individual stock holdings, we find higher probability weighting is associated with owning lottery-type stocks and positively skewed equity portfolios. People with higher probability weighting are less likely to own mutual funds and more likely to either avoid equities or hold individual stocks. We are the first to empirically link individuals’ elicited probability weighting and real-world decisions under risk.

Achieving Portfolio Diversification for Individuals with Low Financial Sustainability

While many individuals make investments to gain financial stability, most individual investors hold under-diversified portfolios that consist of only a few financial assets. Lack of diversification is alarming especially for average individuals because it may result in massive drawdowns in their portfolio returns. In this study, we analyze if it is theoretically feasible to construct fully risk-diversified portfolios even for the small accounts of not-so-rich individuals. In this regard, we formulate an investment size constrained mean-variance portfolio selection problem and investigate the relationship between the investment amount and diversification effect.

Investor Sophistication and Portfolio Dynamics

We develop a simple dynamic general-equilibrium framework that can jointly rationalize many empirically observed features of household portfolios, investment returns, and wealth dynamics. The model differs from traditional models only along a single, natural dimension: households differ in their confidence about the return processes for risky assets. Less-confident households (but with unbiased beliefs) overinvest in safe assets, hold underdiversified portfolios concentrated in familiar assets, are trend chasers, and earn lower absolute and risk-adjusted investment returns. More confident households hold riskier positions and exhibit superior market-timing abilities. Despite Bayesian learning, this investment behavior persists for long periods, thereby exacerbating wealth inequality.

Protecting the Downside of Trend When It Is Not Your Friend

Simple trend-following strategies have been documented as cost-effective, transparent alternatives to the hedge-fund style managed futures strategies. Although largely capturing the returns of the managed futures industry, those simple strategies may periodically suffer significant losses due to oversimplified trend signals and underdiversified portfolio construction. In this article, the authors show that trend-following strategies with moderate sophistication and better diversification can significantly reduce the downside risk of simple trend-following strategies without sacrificing much upside potential. The authors therefore recommend that investors who seek the benefits of cost-effective trend-following strategies consider adding reasonable complexity to the strategies. <b>TOPICS:</b>Real assets/alternative investments/private equity, futures and forward contracts, portfolio construction, risk management

Owners’ Portfolio Diversification and Firm Investment

Abstract Portfolio diversification of firms’ controlling owners influences their firms’ capital investment. Empirically, the effect of owners’ portfolio diversification on their firms’ investment levels is positive for publicly traded firms and tends to be negative for privately held ones. These findings are consistent with predictions of a model in which a risk-averse investor simultaneously chooses her portfolio structure, and both the level and riskiness of capital investment of the firm she controls, and in which the firm can be potentially constrained in its capital investment choices. Overall, our results indicate that owners’ portfolio underdiversification and firms’ financial constraints can affect firms’ resource allocation. Received May 3, 2017; editorial decision March 8, 2019 by Editor Francesca Cornelli. Authors have furnished an Internet Appendix, which is available on the Oxford University Press Web site next to the link to the final published paper online.

Household Portfolio Underdiversification and Probability Weighting: Evidence from the Field

We test whether probability weighting affects household portfolio choice in a representative survey. On average, people display inverse-S shaped probability weighting, overweighting low probability events. As theory predicts, probability weighting is positively associated with portfolio underdiversification and significant Sharpe ratio losses. Analyzing respondents’ individual stock holdings, we find higher probability weighting is associated with owning lottery-type stocks and positively-skewed equity portfolios. People with higher probability weighting are less likely to own mutual funds and more likely to either avoid equities or hold individual stocks. We are the first to empirically link individuals’ elicited probability weighting and real-world decisions under risk.

Individual Investors and Portfolio Diversification in Late Victorian Britain: How Diversified Were Victorian Financial Portfolios?

This article investigates Victorian investor financial portfolio strategies in England and Wales during the second half of the nineteenth century. We find that investors held on average about half of their gross wealth in the form of four or five liquid financial securities, but were reluctant to adopt fully contemporary financial advice to invest equal amounts in securities or to spread risk across the globe. They generally held under-diversified portfolios and proximity to their investments may have been an alternative to diversification as a means of risk reduction, especially for the less wealthy.

Ignorance and Indifference: Decision-Making in the Lab and in the Market

Supplement is available at: https://ssrn.com/abstract=3118417 Economic agents face an evolving, non-ergodic environment. The corresponding permanently undersampled “population” distribution naturally permits unseen, rare events. The principle of indifference, implemented via the methods of parameterization invariance and maximum entropy, provides a disciplined, rational approach to learning, inference and decision in this underinformed setting. Canonical economic problems of choice under uncertainty from both the micro (binary lotteries) and macro (consumption-investment) domains can be formulated in terms of dynamic online learning when new gambles and new regimes are regularly encountered. The implied Bayesian updating under invariant ignorance priors allows to reverse-engineer and rationalize, in a mutually consistent way, the Allais paradox/prospect theory’s probability distortions identified in laboratory experiments as well as the equity premium/risk-free rate, non-monotone pricing kernel and portfolio underdiversification puzzles observed in financial markets.

Do Individual Behavioral Biases Affect Financial Markets and the Macroeconomy?

A common criticism of behavioral economics is that it has not shown that the psychological biases of individual investors lead to aggregate long-run effects on both asset prices and macroeconomic quantities. Our objective is to address this criticism by providing a simple example of a production economy where individual portfolio biases cancel when summed across investors, but still have an effect on aggregate quantities that does not vanish in the long-run. Specifically, we solve in closed form a model of a stochastic general-equilibrium production economy with a large number of heterogeneous firms and investors. Investors in our model are averse to ambiguity and so hold portfolios biased toward familiar assets. We specify this bias to be unsystematic so it cancels out when aggregated across investors. However, because of holding under-diversified portfolios, investors bear more risk than necessary, which distorts the consumption of all investors in the same direction. Hence, distortions in consumption do not cancel out in the aggregate and therefore increase the price of risk and distort aggregate investment and growth. The increased risk from holding biased portfolios, which increases the demand for the risk-free asset, leading to a higher equity risk premium and a lower risk-free rate that match the values observed empirically. Furthermore, all investors survive in the long-run, and so the effects of their biases never vanish. Our analysis illustrates that idiosyncratic behavioral biases can have long-run distortionary effects on both financial markets and the macro-economy.

Funding Shortfall Risk and Asset Prices in General Equilibrium

Institutional investors, such as pensions and insurers, are typically constrained to hold enough wealth to be able to make their contractually promised payments to fund beneficiaries. This creates an additional risk in the economy, namely the risk of funding-shortfall. We seek to explore the optimal asset allocation strategies for institutions facing this risk, and its effects on asset prices. The constraint introduces two distinct regions in the economy, characterising unconstrained and constrained regions, with the possibility of transitioning from the constrained to unconstrained regime, which leads to a two-factor asset pricing model. The funding-shortfall risk increases the conditional equity premium and Sharpe ratio, which evolve counter-cyclically, but decreases the conditional volatility of equity returns, which evolves cyclically. The constrained institution may optimally an under-diversified portfolio, and simultaneously increases its demand for the riskfree and higher-risk assets relative to medium-risk assets, inducing a bubble-like behaviour in the prices of higher-risk assets. The dynamics of contractually promised payments affect the dynamics of conditional moments of asset return distributions, and may lead to predictability. The term structure of interest rates is predominantly upward sloping, but can change shape upon shocks to the growth rate of aggregate dividend relative to the growth rate of minimum payouts. Implied volatility exhibits a time-varying volatility smile, and the term structure of implied volatility can be both upward or downward sloping, depending on the relative growth rates of aggregate dividends and promised institutional payouts. These results may have implications for the design of optimal regulatory requirements.

Log, Stock and Two Simple Lotteries

This work studies the problem of decision-making under risk by agents whose information processing abilities may be limited. The constructed theoretical framework grounds on findings from economic laboratory experiments, incorporates existing neuroscience knowledge, and is implemented using information-theoretic formalism. Activation of the above information-processing constraints distorts the subjective perception of the objective stochastic environment the agent operates in, and the constrained-optimal decision-making requires appropriate adjustments. In the selected application, a general equilibrium macro-finance model, such biases of subjective perspective as overconfidence, pessimism and categorization thus emerge endogenously. The theoretical implications receive empirical support in a mutually consistent way: according to (cross-checked) calibrations, they allow us to reverse-engineer and rationalize the phenomena known as the equity premium/risk-free rate puzzles; as well as contribute to the understanding of such regularities as the portfolio underdiversification puzzle, style investing and the non-monotone pricing kernel puzzle. On the other hand, these results also help rationalize, by formulating certain optimizing foundations behind, the experimental evidence that underlies the Allais paradox and that is systematized in, e.g., the (cumulative) prospect theory.

Does Household Finance Matter? Small Financial Errors with Large Social Costs

Households with familiarity biases tilt their portfolios toward a few risky assets. The resulting mean-variance loss from portfolio underdiversification is equivalent to only a modest reduction of about 1 percent per year in a household’s portfolio return. However, once we consider also the effect of familiarity biases on the asset- allocation and intertemporal consumption-savings decisions, the welfare loss is multiplied by a factor of four. In general equilibrium, the suboptimal decisions of households distort also aggregate growth, amplifying further the overall social welfare loss. Our findings demonstrate that financial markets are not a mere sideshow to the real economy and that improving the financial decisions of households can lead to large benefits, not just for individual households, but also for society. (JEL D14, D91, E21, E44, G11, G41)

Ambiguity aversion and household portfolio choice puzzles: Empirical evidence

We test the relation between ambiguity aversion and five household portfolio choice puzzles: nonparticipation in equities, low allocations to equity, home-bias, own-company stock ownership, and portfolio under-diversification. In a representative US household survey, we measure ambiguity preferences using custom-designed questions based on Ellsberg urns. As theory predicts, ambiguity aversion is negatively associated with stock market participation, the fraction of financial assets in stocks, and foreign stock ownership, but it is positively related to own-company stock ownership. Conditional on stock ownership, ambiguity aversion is related to portfolio under-diversification, and during the financial crisis, ambiguity-averse respondents were more likely to sell stocks.

How Does Household Portfolio Diversification Vary with Financial Sophistication and Advice?

Household investment mistakes are an important concern for researchers and policymakers alike; portfolio underdiversification ranks among those mistakes that are potentially most costly. However, its roots and empirical importance are poorly understood. I estimate quantitatively meaningful diversification statistics and investigate their relationship with key variables. Nearly all households that either score high on financial literacy; or rely on professionals or private contacts for advice; achieve reasonable investment outcomes. Compared to these groups, households with below-median financial literacy that trust their own decision-making capabilities, lose an expected 50bp on average. All group differences stem from the top of the loss distribution.

How Does Household Portfolio Diversification Vary with Financial Literacy and Financial Advice?

ABSTRACTHousehold investment mistakes are an important concern for researchers and policymakers alike. Portfolio underdiversification ranks among those mistakes that are potentially most costly. However, its roots and empirical importance are poorly understood. I estimate quantitatively meaningful diversification statistics and investigate their relationship with key variables. Nearly all households that score high on financial literacy or rely on professionals or private contacts for advice achieve reasonable investment outcomes. Compared to these groups, households with below‐median financial literacy that trust their own decision‐making capabilities lose an expected 50 bps on average. All group differences stem from the top of the loss distribution.

Time Varying Risk Aversion, Familiarity Bias, and Portfolio Concentration During Market Uncertainty

It is well established that international portfolios are far substantially under-diversified, contrary to predictions of traditional finance theory. Even after controlling for market segmentation and “investability” of foreign markets, portfolio under-diversification remains a puzzle. I study global portfolio under-diversification during periods of varying market uncertainty. My empirical hypotheses are based on a psychological theory that relates uncertainty in the markets to increases in investors’ risk aversion which in turn increases investors’ proneness to familiarity bias. I hypothesize that during heightened market uncertainty, investors become more under-diversified and focus their holdings in familiar markets. I indeed show that in addition to “flight to quality” there exists a strong “flight to familiarity” effect, when global volatility is high. The average home bias and country concentration of investors’ foreign holdings are of 8-10% larger during periods of heightened market uncertainty. In addition, familiarity variables that affect portfolio allocation, such as common language, culture, and geographical distance become more significant drivers of equity allocation.

Ownership concentration, contestability, family firms, and capital structure

This study analyses the distribution of power among the several blockholders of a firm and the identity of those blockholders as a determinant of firm leverage. Using a sample of 694 firms from 12 Western European countries, our results support a negative relationship between ownership concentration in the hands of the main blockholder and firm leverage. Moreover, we detect that the presence of a second and third large shareholder (beyond the first blockholder) has a significant positive effect on the leverage ratio. In addition, the results show that contestability in family firms plays a more relevant role. Finally, we show that family firms do have significant impact on firm leverage level, and this impact varies depending on the legal framework and institutional environment. In our main sample the results show family firms negatively affect market leverage, supporting the theory that family firms are more averse to an increase in the debt level due to the risk of bankruptcy and financial distress as a result of having an under-diversified portfolio. In contrast, the opposite effect is found in the sample that excludes the United Kingdom. This last result cannot be explained by agency theory, given that family businesses are those that suffer less from Type I agency problems. This result suggests either some difficulty in financing their investments by issuing new equity or the need to use debt as a signal of the quality of its investments. Our results prove to be stable against a battery of robustness tests.