Dynamic optimal portfolio choice in a jump-diffusion model with investment constraints

We consider the dynamic portfolio choice problem in a jump-diffusion model, where an investor may face constraints on her portfolio weights: for instance, no-short-selling constraints. It is a daunting task to use standard numerical methods to solve a constrained portfolio choice problem, especially when there is a large number of state variables. By suitably embedding the constrained problem in an appropriate family of unconstrained ones, we provide some equivalent optimality conditions for the indirect value function and optimal portfolio weights. These results simplify and help to solve the constrained optimal portfolio choice problem in jump-diffusion models. Finally, we apply our theoretical results to several examples, to examine the impact of no-short-selling and/or no-borrowing constraints on the performance of optimal portfolio strategies.     

Does Faith Matter in Mutual Funds Investing? Evidence from Saudi Arabia

This article investigates one of the most vital issues in the Islamic mutual fund literature: Are there any costs associated with investing in Islamic mutual funds? We used a unique sample of 143 Saudi mutual funds and grouped them into portfolios based on their geographical focus, Shariah compliance, and the Saudi market trend (overall, bull, bear, and the crisis period). Findings suggest there is a benefit from adhering to Shariah law in locally-focused Saudi mutual funds. However, there is a cost of this adherence in internationally-focused Saudi mutual funds. Finally, in Arab-focused Saudi mutual funds, there is neither a cost nor a benefit.     

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.     

Performance analysis of a collateralized fund obligation (CFO) equity tranche

This article examines the performance of the junior tranche of a collateralized fund obligation (CFO), i.e. the residual claim (equity) on a securitized portfolio of hedge funds. We use a polynomial goal programming model to create optimal portfolios of hedge funds, conditional to investor preferences and diversification constraints (maximum allocation per strategy). For each portfolio, we build CFO structures that have different levels of leverage, and analyze both the stand-alone performance as well as potential diversification benefits (low systematic risk exposures) of investing in the equity tranche of these structures. We find that the unconstrained mean-variance portfolio yields a high performance, but greater exposure to systematic risk. We observe the exact opposite picture in the case of unconstrained optimization, where a skewness bias is added, thus proving the existence of a trade-off between stand-alone performance and low exposure to systematic risk factors. We provide evidence that leveraged exposure to these hedge fund portfolios through the structuring of CFOs creates value for the equity tranche investor, even during the recent financial crisis.     

On the price of risk in a mean-risk optimization model

We investigate a mean-risk model for portfolio optimization where the risk quantifier is selected as a semi-deviation or as a standard deviation of the portfolio return. We analyse the existence of solutions to the problem under general assumptions. When the short positions are not constrained, we establish a lower bound on the cost of risk associated with optimizing the mean–standard deviation model and show that optimal solutions do not exist for any positive price of risk which is smaller than that bound. If the investment allocations are constrained, then we obtain a lower bound on the price of risk in terms of the shadow prices of said constraints and the data of the problem. A Value-at-Risk constraint in the model implies an upper bound on the price of risk for all feasible portfolios. Furthermore, we provide conditions under which using this upper bound as the cost of risk parameter in the model provides a non-dominated optimal portfolio with respect to the second-order stochastic dominance. Additionally, we study the relationship between minimizing the mean–standard deviation objective and maximizing the coefficient of variation and show that both problems are equivalent when the upper bound is used as the cost of risk. Additional relations between the Value-at-Risk constraint and the coefficient of variation are discussed as well. We illustrate the results numerically.     

Country and currency diversification of bond investments: do they really make sense for Swiss investors?

The inclusion of hedged or unhedged foreign currency bonds within a strategic asset allocation is a crucial decision which should be analyzed carefully. The goal of this paper is to provide a contribution to this analysis by focusing particularly on the time horizon of the investment. Results are analyzed from the perspective of a Swiss investor. We find that over the last 21 years, investing in bonds denominated in Swiss Francs has been clearly less efficient in terms of risk-adjusted returns than investing in a hedged global bond portfolio. For short-term investors, we find robust evidence against the hypothesis of investing in unhedged foreign currency bonds. The picture changes dramatically, however, when we consider an investment horizon of 6 years and the normal case of balanced portfolios including also equities and domestic bonds. In this case, the optimal strategy for the period we analyzed would have been to hedge only the exposure to US dollar bonds.      

Long-horizon event studies and event firm portfolio weights: Evidence from U.K. rights issues re-visited

Empirical results, in long-horizon event studies, are sensitive to whether equal- or value-weighting schemes are used to form event firm portfolios. In this paper we propose, as a first step, an evaluation of the economic value to investing in an equal-weighted and a value-weighted event firm portfolio prior to the event study. Using tests for mean-variance spanning we find in our data a significant improvement in an investor's investment opportunity set to investing in an equal-weighted portfolio. We then re-visit the long-run post-offer performance for rights issuers in the U.K. where we find, as in other studies, differences in both the magnitude and statistical significance of abnormal performance for value-weighted and equal-weighted event firm portfolios. We then use the results from our first step to provide an economic rationale for interpreting our results. A general conclusion we draw is that it may be useful to first ascertain, in long-horizon event studies, the economic value of portfolio weighting schemes as this can then provide some guidance to the use of a specific portfolio weighting scheme and thereby to interpretation of often conflicting results.     

Corporate Sustainability Performance and Idiosyncratic Risk: A Global Perspective

Does investing in sustainability leaders affect portfolio performance? Analyzing two mutually exclusive leading and lagging global corporate sustainability portfolios (Dow Jones) finds that (1) leading sustainability firms do not underperform the market portfolio, and (2) their lagging counterparts outperform the market portfolio and the leading portfolio. Notably, we find leading (lagging) corporate social performance (CSP) firms exhibit significantly lower (higher) idiosyncratic risk and that idiosyncratic risk might be priced by the broader global equity market. We develop an idiosyncratic risk factor and find that its inclusion significantly reduces the apparent difference in performance between leading and lagging CSP portfolios.     

Corporate Social Responsibility,Shariah-Compliance,and Earnings Quality

This study examines the effect of two potential sources of ethical principles on earnings quality: corporate social responsibility (CSR) and membership in a Shariah index. We define membership in a Shariah index as the adherence to an ethical code that relates to Islam. Our sample comprises firms in ten European Union countries for the period from 2003 to 2013. The empirical results show that firms with a high degree of CSR are less likely to manage earnings. In contrast, membership in a Shariah index leads to earnings manipulation. Our results are robust after using several alternative quality metrics for earnings. Furthermore, our empirical results indicate that highly rated CSR firms that are not Shariah-compliant are less likely to engage in earnings manipulation. Further, institutional factors are also important in determining the link between CSR, Shariah-compliance, and the quality of financial reporting.     

Are better governed funds better monitors?

Using Morningstar mutual fund stewardship grade data, we find that the governance mechanisms of mutual funds play a key role in their monitoring of portfolio firms and in their investment decisions. Mutual funds with better governance practices tend to vote responsibly on corporate governance proposals of their portfolio firms and also provide better return performance. Furthermore, these funds tend to avoid investing in poorly governed firms. The results suggest that funds with quality governance are more likely to act in the interest of their investors, and that costs associated with funds' monitoring of their portfolio firms do not adversely affect their return performance.     

A Value-At-Risk Calculation of Required Reserves for Credit Risk in Corporate Lending Portfolios

This paper demonstrates that the building blocks of the insurance process, under similar assumptions, produce identical results to the option-pricing approach in the case of pricing individual loans. We examine the performance of a collective of such building blocks, using portfolio historical performance to endogenously parameterize the default cost function unique to a particular portfolio. Having estimated the appropriate default cost function, we can then specify the reserve requirement for a bank operating such a portfolio. In this respect, the additivity of the Poisson parameter is a powerful feature, allowing one to decompose portfolio performance over time and homogeneous portfolio subsections. Portfolios with greater and lesser risk and profitability respectively are hypothesized, and a capital adequacy framework which equates risk across such portfolios is examined. Finally, we simulate the operation of the proposed capital adequacy model. Observed insolvencies are fewer than those observable under present regulation, and specific problems may be identified earlier than at present.     

Portfolio selection with a drawdown constraint

When identifying optimal portfolios, practitioners often impose a drawdown constraint. This constraint is even explicit in some money management contracts such as the one recently involving Merrill Lynch’ management of Unilever’s pension fund. In this setting, we provide a characterization of optimal portfolios using mean–variance analysis. In the absence of a benchmark, we find that while the constraint typically decreases the optimal portfolio’s standard deviation, the constrained optimal portfolio can be notably mean–variance inefficient. In the presence of a benchmark such as in the Merrill Lynch–Unilever contract, we find that the constraint increases the optimal portfolio’s standard deviation and tracking error volatility. Thus, the constraint negatively affects a portfolio manager’s ability to track a benchmark.     

Shariah compliance and corporate cash holdings

This study investigates the influence of Shariah compliance status on cash holding levels and the speed of adjustment of non-financial listed firms in six Gulf Cooperation countries from 2005 to 2016. The results show that Shariah compliance status has a significant effect on firms’ cash holding decisions. Shariah-compliant firms have significantly higher cash holding levels than non-Shariah-compliant firms. Further, Shariah-compliant firms adjust more quickly towards their target cash holdings than their conventional counterparts. In our view, Shariah-compliant firms are subject to multiple restrictions that limit their external financing channels. Therefore, holding larger cash reserves is important as it helps gain from the transaction cost motive of holding cash. The findings of this study have important implications for regulators, investors and managers. To the best of our knowledge, this study is the first to compare the effect of Shariah compliance on firms’ cash holdings and the speed of adjustment towards the trade-off theory’s optimal cash holding target.     

The Effect of Market Regimes on Style Allocation

We analyse time-varying risk premia and the implications for portfolio choice. Using Markov Chain Monte Carlo (MCMC) methods, we estimate a multivariate regime-switching model for the Carhart (1997) four-factor model. We find two clearly separable regimes with different mean returns, volatilities, and correlations. In the High-Variance Regime, only value stocks deliver a good performance, whereas in the Low-Variance Regime, the market portfolio and momentum stocks promise high returns. Regime-switching induces investors to change their portfolio style over time depending on the investment horizon, the risk aversion, and the prevailing regime. Value investing seems to be a rational strategy in the High-Variance Regime, momentum investing in the Low-Variance Regime. An empirical out-of-sample backtest indicates that this switching strategy can be profitable, but the overall forecasting ability for the regime-switching model seems to be weak compared to the iid model.     

Performance of impact investing: A value creation approach

The purpose of this article is to present an overview about the origins of value creation in impact investing and propose a measure of value creation. According to this point of view, impact investing, i.e. investing in enterprises with a both social and financial objective can be justified only if those enterprises can provide for a higher performance than with a simple portfolio diversification (separate investment in two types of activity). After an overview about the sources of value creation in impact investees as well as about a discussion on existing methods, we propose a method to measure multidimensional value creation.     

Do ADRs enhance portfolio performance for a domestic portfolio? Evidence from the 1990s

American depository receipts (ADRs) represent an increasingly popular and convenient mechanism for international investing. We analyze ADRs traded throughout the 1990s and find that these securities offer a diversification and portfolio performance benefit when combined with a domestic portfolio (proxied by the S&P 500). While we find that emerging market ADRs are effective instruments for reducing portfolio risk, they do not improve portfolio performance as measured by the Sharpe ratio. Developed market ADRs do improve portfolio performance as measured by the Sharpe ratio. The asset allocation which maximizes the Sharpe ratio is 84 percent domestic stocks, 16 percent developed ADRs, and 0 percent emerging ADRs. Further, due to problems in defining an appropriate market index for ADRs, the Sharpe ratio is viewed to be the preferred performance measure. Other measures such as Jensen’s alpha and the Treynor measure are susceptible to being “gamed” to distort portfolio performance.     

Conditional performance, portfolio rebalancing, and momentum of small-cap mutual funds

To assess the performance of small-cap stocks net of transaction costs, we analyze 165 actively managed small-cap oriented portfolios. Our analysis addresses three areas of interest: (i) performance net of transaction costs, (ii) the magnitude of trading costs incurred when rebalancing an actively managed portfolio, and (iii) the potential for momentum strategy profits when investing in small-cap stocks.Using conditional estimation, we find that small-cap funds have earned a significantly positive abnormal return of about 2% per year in the period January 1986 to December 2000. We also estimate the cost of January rebalancing to be 0.4% of portfolio value, a value that is significant for over 20% of the portfolios under study.Finally, after trading frictions are taken into account, we find evidence that small-cap portfolios exhibit significant return patterns, similar in nature to momentum patterns initially documented in a frictionless setting by [J. Finance 48 (1993) 65; J. Finance 56 (2001) 699]. Our findings support recent behavioral models, which attempt to explain these patterns. Consistent with the findings of Jegadeesh and Titman, we find that past “winners” continue to outperform in the next 12 months, followed by a performance reversal.     

Reduction of estimation risk in optimal portfolio choice using redundant constraints

It is well known that when the moments of the distribution governing returns are estimated from sample data, the out-of-sample performance of the optimal solution of a mean–variance (MV) portfolio problem deteriorates as a consequence of the so-called “estimation risk”. In this document we provide a theoretical analysis of the effects caused by redundant constraints on the out-of-sample performance of optimal MV portfolios. In particular, we show that the out-of-sample performance of the plug-in estimator of the optimal MV portfolio can be improved by adding any set of redundant linear constraints. We also illustrate our findings when risky assets are equally correlated and identically distributed. In this specific case, we report an emerging trade-off between diversification and estimation risk and that the allocation of estimation risk across portfolios forming the optimal solution changes dramatically in terms of number of assets and correlations.     

The holding behavior of Shariah financial assets within the global Islamic financial sector: A macroeconomic and firm-based model

The extant academic literature has shown the distinct differences between Islamic and conventional financial institutions along either a performance or efficiency front with an attribution to these differences to the adoption of a religio-financial framework merging the principles of economics and finance with those of Shariah. However, these empirical estimations do not entirely capture the religio-financial framework since they use performance and efficiency measures that include both conventional and Shariah transactions. We address this gap in the literature by examining the dynamics influencing the holding behavior of Shariah assets by Islamic financial institutions (IFIs). Given that the a priori hypothecation of Shariah asset holding behavior is relatively nebulous, we draw extensively from the traditional macroeconomic and managerialist literature in building our econometric model. By exploiting a unique and proprietary dataset comprising 140 Islamic financial institutions operating in 16 different countries over the time period 2011–2015, we find that economic wealth, market liquidity and the institutional board size are robust and positive linear predictors of IFI Shariah assets' holding behavior, thus providing support for the traditional macroeconomic theory of asset demand and firm-based agency theory.     

Markowitz投资组合模型的最小二乘算法

本文从一个新的视角来研究Markowitz均值—方差模型。通过将Markowitz均值—方差模型表述为约束最小二乘问题,继而使用约束最小二乘问题的算法研究了协方差矩阵正定和半正定时模型的求解问题,我们给出了计算投资组合有效前沿及最小方差组合的新算法。实证分析表明：最小二乘算法在计算稳定和计算速度方面优于传统算法。