Equity Home‐Bias: A Suboptimal Choice for UK investors?

In spite of the popularity of international portfolio diversification theory, extant empirical literature shows that investors prefer domestic assets and as a result, many studies argue that investors' portfolios are largely suboptimal. This paper examines whether British investors need to diversify their portfolios internationally to gain performance benefits from international markets or can they obtain these benefits by mimicking the portfolios with domestically traded assets. The results confirm that it is possible to mimic the performance of foreign equity with domestic equity. Indeed, the pay‐offs from homemade portfolios outperform those from international portfolios regardless of the periodic variation in the overall performance of the UK market vis‐à‐vis foreign markets. The superiority of homemade portfolio is more prominent in recent years and is enhanced by the increased internationalisation of developed capital markets. Therefore, investors' home bias is not suboptimal.     

Investors’ aspirations and portfolio performance

Based on a large database of individual investors, I analyze the impact of personal financial goals on portfolio performance. I stress the role played by latent investor aspirations as defined in the Behavioral Portfolio Theory framework. I identify two opposite profiles of investors. High-aspirations investors trade more and hold riskier portfolios than the average investor. By contrast, low-aspirations investors are more diversified than the average investor. I find that when controlling for diversification, turnover and usual risk factors, high-aspiration investors underperform their peers, whereas low-aspirations investors outperform them.     

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.     

Long‐Run Stockholder Consumption Risk and Asset Returns

We provide new evidence on the success of long‐run risks in asset pricing by focusing on the risks borne by stockholders. Exploiting microlevel household consumption data, we show that long‐run stockholder consumption risk better captures cross‐sectional variation in average asset returns than aggregate or nonstockholder consumption risk, and implies more plausible risk aversion estimates. We find that risk aversion around 10 can match observed risk premia for the wealthiest stockholders across sets of test assets that include the 25 Fama and French portfolios, the market portfolio, bond portfolios, and the entire cross‐section of stocks.     

HOW MANY SMALL FIRMS ARE ENOUGH?

Individual investors are undiversified, holding on average less than four securities in their personal portfolios. The small firm literature focuses on CAPM (systematic risk, full diversification concept) premia, and the actual performance of small firm portfolios held by investors is overstated because of the presence of unsystematic risk. This paper illustrates the magnitudes of total risk for small and large firms, and the behavior of such measures as portfolio size is altered. Small firms contain more risk as shown by the finding that a diversified portfolio of small firms has greater variability than a single, typical large firm. While small firms outperform large firms, investors should be aware of the implications for small firm undiversified portfolios. Because small firms contain large amounts of unsystematic risk, diversification is important if investors are going to capture the small firm premia reported in the literature.     

The Diversification Effects of Initial Public Offerings

Abstract:  A firm's stock becomes publicly tradable through an initial public offering (IPO). This study suggests a portfolio diversification perspective to explore IPOs. We examine whether investors can gain diversification benefits by adding an IPO portfolio to a set of benchmark portfolios sorted by firm size and book-to-market ratio. Using US IPOs from 1980-2002, we find that adding a value-weighted IPO portfolio does lead to a statistically and economically significant enlargement of the investment opportunity set for investors relative to investing solely in a set of benchmark portfolios. Specifically, the Sharpe ratio of the tangency portfolio increases by 5.50% on average after including IPO stocks. Furthermore, IPOs associated with prestigious lead underwriters are the main source of this augmentation of the mean-variance investment opportunity set. Finally, our study implies that issuing IPO exchange traded funds or similar products can provide diversification gains to investors.     

Using industry momentum to improve portfolio performance

Minimum-variance portfolios, which ignore the mean and focus on the (co)variances of asset returns, outperform mean–variance approaches in out-of-sample tests. Despite these promising results, minimum-variance policies fail to deliver a superior performance compared with the simple 1/N rule. In this paper, we propose a parametric portfolio policy that uses industry return momentum to improve portfolio performance. Our portfolio policies outperform a broad selection of established portfolio strategies in terms of Sharpe ratio and certainty equivalent returns. The proposed policies are particularly suitable for investors because portfolio turnover is only moderately increased compared to standard minimum-variance portfolios.     

Cross‐sectional Tests of Conditional Asset Pricing Models: Evidence from the German Stock Market

We study the performance of conditional asset pricing models and multifactor models in explaining the German cross‐section of stock returns. We focus on several variables, which (according to previous research) are associated with market expectations on future market excess returns or business cycle conditions. Our results suggest that the empirical performance of the Capital Asset Pricing Model (CAPM) can be improved when allowing for time‐varying parameters of the stochastic discount factor. A conditional CAPM using the term spread explains the returns on our size and book‐to‐market sorted portfolios about as well as the Fama‐French three‐factor model and performs best in terms of the Hansen‐Jagannathan distance. Structural break tests do not necessarily indicate parameter instability of conditional model specifications. Another major finding of the paper is that the Fama‐French model – despite its generally good cross‐sectional performance – is subject to model instability. Unconditional models, however, do a better job than conditional ones at capturing time‐series predictability of the test portfolio returns.     

Experimental Evidence on Portfolio Size and Diversification: Human Biases in Naïve Security Selection and Portfolio Construction

We conduct an experiment in which individuals select securities to reproduce the well‐known relationship between portfolio risk and the number of securities. The standard result occurs on average but not for most individuals, many of whom effectively de‐diversify as they add seemingly random securities. Moreover, only slightly better results are achieved using a random number generator. This finding challenges the belief that only a small number of securities are required for diversification and shows that it is applicable only to a large sample. The implications are important given that many individual investors hold very few stocks in their portfolios.     

An empirical examination of the benefits of international diversification

We examine the benefits of international portfolio diversification for U.K. investors between January 1985 and December 2000 using the approach of Wang [Wang, Z., 1998. Efficiency loss and constraints on portfolio holdings. Journal of Financial Economics 48, 359–375] and Li et al. [Li, K., Sarkar, A., Wang, Z., 2003. Diversification benefits of emerging markets subject to portfolio constraints. Journal of Empirical Finance 10, 57–80]. We find significant increases in the Sharpe [Sharpe, W.F., 1966. Mutual fund performance. Journal of Business 39, 119–138] and certainty equivalent return (CER) performance in moving from a domestic strategy to an international strategy that includes either global industry or country equity portfolios, even in the presence of short selling restrictions. We also find significant diversification benefits using U.K. unit trusts with international equity objectives. However, U.K. international unit trusts do not capture all the diversification benefits provided by either global industry or country equity portfolios.     

Naïve Buying Diversification and Narrow Framing by Individual Investors

We provide the first tests to distinguish whether individual investors equally balance their overall portfolios (naïve portfolio diversification, NPD) or, in contrast, equally balance the values of same-day purchases of multiple assets (naïve buying diversification, NBD). We find NBD in purchases of multiple stocks, and in mixed purchases of individual stocks and funds. In contrast, there is little evidence of NPD. Evidence suggests that NBD arises due to stock picking behavior and neglect of diversification. These findings suggest that behavioral finance theory should incorporate transaction, as well as portfolio, framing.     

Maximizing an equity portfolio excess growth rate: a new form of smart beta strategy?

It has been claimed that, for dynamic investment strategies, the simple act of rebalancing a portfolio can be a source of additional performance, sometimes referred to as the volatility pumping effect or the diversification bonus because volatility and diversification turn out to be key drivers of the portfolio performance. Stochastic portfolio theory suggests that the portfolio excess growth rate, defined as the difference between the portfolio expected growth rate and the weighted-average expected growth rate of the assets in the portfolio, is an important component of this additional performance (see Fernholz [Stochastic Portfolio Theory, 2002 (Springer)]). In this context, one might wonder whether maximizing a portfolio excess growth rate would lead to an improvement in the portfolio performance or risk-adjusted performance. This paper provides a thorough empirical analysis of the maximization of an equity portfolio excess growth rate in a portfolio construction context for individual stocks. In out-of-sample empirical tests conducted on individual stocks from 4 different regions (US, UK, Eurozone and Japan), we find that portfolios that maximize the excess growth rate are characterized by a strong negative exposure to the low volatility factor and a higher than 1 exposure to the market factor, implying that such portfolios are attractive alternatives to competing smart portfolios in markets where the low volatility anomaly does not hold (e.g. in the UK, or in rising interest rate scenarios) or in bull market environments.     

Equity portfolio diversification with high frequency data

Investors wishing to achieve a particular level of diversification may be misled on how many stocks to hold in a portfolio by assessing the portfolio risk at different data frequencies. High frequency intradaily data provide better estimates of volatility, which translate to more accurate assessment of portfolio risk. Using 5-min, daily and weekly data on S&P500 constituents for the period from 2003 to 2011, we find that for an average investor wishing to diversify away 85% (90%) of the risk, equally weighted portfolios of 7 (10) stocks will suffice, irrespective of the data frequency used or the time period considered. However, to assure investors of a desired level of diversification 90% of the time (in contrast to on average), using low frequency data results in an exaggerated number of stocks in a portfolio when compared with the recommendation based on 5-min data. This difference is magnified during periods when financial markets are in distress, as much as doubling during the 2007–2009 financial crisis.     

DIVERSIFICATION AND SKEWNESS IN OPTION PORTFOLIOS

Skewness in returns is relevant to option investors. Because options possess positively skewed distributions, the traditional maxim of diversification, which can destroy positive skewness, is not necessarily consistent with investment objectives. The results indicate that the majority of skewness in option portfolios is diversified with a relatively small portfolio size, suggesting a strategy of antidiversification for option investors. Even though the investment performance of options is inferior to stocks on a risk-return basis, the data indicate the suitability of option portfolios in an environment where an investor's utility is measured by the return, risk, and skewness of the return distribution.     

Individual home bias,portfolio churning and performance

This study investigates economic consequences of individual investors’ home bias and portfolio churning in their personal pension accounts. The empirical analysis is carried out within a Heckman style two-stage framework to account for selection bias with respect to individuals’ investment activity, and to allow for an endogenously determined home bias, portfolio churning and performance. Results indicate that home bias induces a worse risk-adjusted performance. Home-biased individuals’ relatively bad performance originates in insufficient risk-reduction, due to a lack of international diversification. A higher degree of portfolio churning also deteriorates performance, despite the fact that churning is not associated with any direct transaction costs. However, home-biased individuals do not churn portfolios as often as individuals with a larger share of international asset holdings, which diminishes the negative effects of home bias on performance. Overconfidence is driven by a return-chasing behavior, where overconfident individuals favor international assets with high historical returns. Individuals with actual skill are more often men than women, are not tempted by high historical returns, and use international assets for the right reason – diversification.     

Systemic Liquidation Risk and the Diversity–Diversification Trade‐Off

This paper proposes a portfolio choice model in which investors are subject to liquidation risk and (endogenously) face higher costs in the event of joint liquidation (as was observed during the crisis of 2008 to 2009). The risk of joint liquidation creates an incentive for investors to choose heterogeneous portfolios and to rationally forgo diversification benefits. Joint liquidation risk is also reflected in asset prices, resulting in (1) assets with high idiosyncratic risk having low expected returns, and (2) assets that display high correlation with the portfolios of (liquidation‐prone) investors having high expected returns.     

Multi-asset portfolio optimization and out-of-sample performance: an evaluation of Black–Litterman,mean-variance,and naïve diversification approaches

The Black–Litterman model aims to enhance asset allocation decisions by overcoming the problems of mean-variance portfolio optimization. We propose a sample-based version of the Black–Litterman model and implement it on a multi-asset portfolio consisting of global stocks, bonds, and commodity indices, covering the period from January 1993 to December 2011. We test its out-of-sample performance relative to other asset allocation models and find that Black–Litterman optimized portfolios significantly outperform naïve-diversified portfolios (1/N rule and strategic weights), and consistently perform better than mean-variance, Bayes–Stein, and minimum-variance strategies in terms of out-of-sample Sharpe ratios, even after controlling for different levels of risk aversion, investment constraints, and transaction costs. The BL model generates portfolios with lower risk, less extreme asset allocations, and higher diversification across asset classes. Sensitivity analyses indicate that these advantages are due to more stable mixed return estimates that incorporate the reliability of return predictions, smaller estimation errors, and lower turnover.     

A Stability Approach to Mean‐Variance Optimization

I jointly treat two critical issues in the application of mean‐variance portfolios, that is, estimation risk and portfolio instability. I find that theory‐based portfolio strategies, which are known to outperform naive diversification () in the absence of transaction costs, heavily underperform it under transaction costs. This is because they are highly unstable over time. I propose a generic method to stabilize any given portfolio strategy while maintaining or improving its efficiency. My empirical analysis confirms that the new method leads to stable and efficient portfolios that offer equal or lower turnover than and larger Sharpe ratio, even under high transaction costs.     

Islamic and conventional portfolios optimization under investor sentiment states: Bayesian vs Markowitz portfolio analysis

This paper investigates the portfolio optimization under investor’s sentiment states of Hidden Markov model and over a different time horizon during the period 2004–2016. To compare the efficient portfolios of the Islamic and the conventional stock indexes, we have employed two approaches: the Bayesian and Markowitz mean-variance. Our findings reveal that the Bayesian efficient frontier of Islamic and conventional stock portfolios is affected by the investor’s sentiment state and the time horizon. Our findings also indicate that the investor’s sentiment regimes change the Islamic and the conventional optimal diversified portfolios.Moreover, the results show that the potential diversification benefits seem to be more important when using the Bayesian approach than when applying the Markowitz approach. This finding is valid for the bearish, depressed, bullish and calm states in Islamic stock markets. However, the diversification of potential portfolios is significant only for the bullish and the bubble states in the conventional financial markets.The findings of the study provided additional evidence for investors to exploit googling investor sentiment states to evaluate the portfolio performance and make an optimal portfolio allocation.     

On the investment credentials of Bitcoin: A cross-currency perspective

We examine diversification capabilities of Bitcoin for a global portfolio spread across six asset classes from the standpoint of investors dealing in five major fiat currencies namely US Dollar, Great Britain Pound, Euro, Japanese Yen and Chinese Yuan. Considering the period of prolonged decline in Bitcoin’s value throughout 2018, we employ modified conditional value-at-risk and standard deviation as measures of risk to perform portfolio optimisations across three asset allocation strategies. Results show that portfolios denominated in Japanese Yen, Chinese Yuan and US Dollar account for greater proportion of optimal investment in Bitcoin and exhibit higher improvement in risk-adjusted returns due to investment in Bitcoin. We also perform a comprehensive risk-adjusted evaluation of portfolios with and without Bitcoin to reinforce striking variation in degree of diversification benefits of Bitcoin in a cross-currency context. Taken together, our findings provide insights into sharp disparity in Bitcoin trading volumes across national currencies from a portfolio theory perspective.