Equally Weighted Portfolios of Randomly Selected Stocks and the Individual Investor

The article contrasts 500 randomly formed equally weighted portfolios (1/N) to 221 actively managed stock funds, individual stocks, and the IBrX-50 index, representing indexed stock funds, considering transaction costs. The sample are the 50 stocks in IBrX-50 index in January 2007 throughout 60 months. Investors are likely to achieve greater returns and return-to-risk ratios with a randomly formed 1/N portfolio than with a stock fund, particularly those targeting retail investors, or one of the 50 stocks also randomly drawn. These portfolios would also outperform the IBrX-50. Robustness tests with variations in size and frequency of rebalancing do not change conclusions.     

Stability of mutual fund systematic risk statistics

Empirical data for 85 mutual funds are used to test the intertemporal stability of their systematic risk statistics. Reasons why the portfolios may be nonstationary are suggested. A random coefficient model developed by Theil [37] is employed to test for the stability of each fund's beta. The data suggest that some funds do exhibit a beta that is best described as being a random coefficient. However, the percentage of funds exhibiting this characteristic was not statistically different from the percentage of randomly created portfolios that exhibited a random beta coefficient. The findings of this study support the statistical models employed in two other recent studies [18,21] to test for the stability of beta. Yet, for mutual funds that do exhibit a random beta coefficient, the partitioning of the total risk of the portfolio return into systematic and unsystematic risk is no longer valid for explaining the total risk.     

基于VaR和两基金分离的投资组合模型

本文使用VaR来度量投资组合的市场风险,构造了一个在可接受期末财富约束条件下,使VaR达到最小的投资组合模型,同时,发现该模型发生了两基金分离现象,因此存在多风险资产情形下的投资组合模型可以退化成为单风险资产情形下的投资组合模型。最后,本文使用简化的单风险模型对我国上海股票市场进行了实证分析,探讨投资者如何在股票和银行借贷中进行最优资产分配。     

The comparative role of iShares and country funds in internationally diversified portfolios

This paper examines the performance and diversification gains provided by iShares versus closed-end country funds over the period 1996 through 2006. Findings include: (1) iShares reveal weaker effects from U.S. market exposure than do country funds; (2) U.S. investors react similarly to foreign currency risk associated with iShares and country funds; (3) the average risk-adjusted performance of passively managed iShares is better than that of their respective actively managed country funds; and (4) iShares provide U.S. investors greater diversification gains than do country funds, that is, U.S. investors should prefer iShares to country funds when diversifying portfolios internationally.     

UNIVERSAL SEMICONSTANT REBALANCED PORTFOLIOS

In this paper, we investigate investment strategies that can rebalance their target portfolio vectors at arbitrary investment periods. These strategies are called semiconstant rebalanced portfolios in Blum and Kalai and Helmbold et al. Unlike a constant rebalanced portfolio, which must rebalance at every investment interval, a semiconstant rebalanced portfolio rebalances its portfolio only on selected instants. Hence, a semiconstant rebalanced portfolio may avoid rebalancing if the transaction costs outweigh the benefits of rebalancing. In a competitive algorithm framework, we compete against all such semiconstant portfolios with an arbitrary number of rebalancings and corresponding rebalancing instants. We investigate this framework with and without transaction costs and demonstrate sequential portfolios that asymptotically achieve the wealth of the best semiconstant rebalanced portfolios whose number of rebalancings and instants of rebalancings are tuned to the individual sequence of price relatives.     

ROBUST PORTFOLIOS AND WEAK INCENTIVES IN LONG‐RUN INVESTMENTS

When the planning horizon is long, and the safe asset grows indefinitely, isoelastic portfolios are nearly optimal for investors who are close to isoelastic for high wealth, and not too risk averse for low wealth. We prove this result in a general arbitrage‐free, frictionless, semimartingale model. As a consequence, optimal portfolios are robust to the perturbations in preferences induced by common option compensation schemes, and such incentives are weaker when their horizon is longer. Robust option incentives are possible, but require several, arbitrarily large exercise prices, and are not always convex.     

Adoption of multiple electronic marketplaces: Antecedents from a grounded theory study

To achieve economies of scope, most motor carriers combine long-term contracts with shippers and brokers with periodic spot assignments found on electronic marketplaces (EMs). While previous research has addressed how carriers adopt an EM, we know little about factors that influence carriers to adopt multiple EMs. Given the rise of the platform economy of the trucking industry, we chose to address this gap and generate mid-range theory on adopting multiple EMs in a logistics context. To do this, we applied grounded theory and conducted 23 interviews with motor carriers and EM experts in North America and Europe until we reached theoretical saturation. Our findings reveal that many motor carriers adopt a portfolio of different EMs, and that their awareness of platforms, expected and realized benefits, attitude, and vigilance determine how they configure their EM portfolios. The implication for existing theory is that, while previous studies depicted EM adoption from a single-system perspective, we found that it is actually a continuous selection process that follows a portfolio perspective. Our paper also has implications for practice in that it illuminates the rationales behind EM portfolio development and identifies actionable factors that can help managers configure stronger portfolios.     

CONTINUOUS-TIME MEAN-VARIANCE PORTFOLIO SELECTION WITH BANKRUPTCY PROHIBITION

A continuous-time mean-variance portfolio selection problem is studied where all the market coefficients are random and the wealth process under any admissible trading strategy is not allowed to be below zero at any time. The trading strategy under consideration is defined in terms of the dollar amounts, rather than the proportions of wealth, allocated in individual stocks. The problem is completely solved using a decomposition approach. Specifically, a (constrained) variance minimizing problem is formulated and its feasibility is characterized. Then, after a system of equations for two Lagrange multipliers is solved, variance minimizing portfolios are derived as the replicating portfolios of some contingent claims, and the variance minimizing frontier is obtained. Finally, the efficient frontier is identified as an appropriate portion of the variance minimizing frontier after the monotonicity of the minimum variance on the expected terminal wealth over this portion is proved and all the efficient portfolios are found. In the special case where the market coefficients are deterministic, efficient portfolios are explicitly expressed as feedback of the current wealth, and the efficient frontier is represented by parameterized equations. Our results indicate that the efficient policy for a mean-variance investor is simply to purchase a European put option that is chosen, according to his or her risk preferences, from a particular class of options.     

Further evaluation of conglomerate performance

In the early years conglomerates were seen as the financial concept of the future. More recently their economic advantages have been seriously questioned. This article reviews the existing literature on conglomerate performance and extends the investigation through the early seventies. While conglomerates provide investors with less variability from market movements than do nonconglomerate firms, they provide less diversification than closed-end investment companies and mutual funds. Furthermore, risk adjusted performance measures of conglomerates did not differ significantly from those of other firms of portfolios. Thus, conglomerates should be viewed simply as another category of investments that plot along the security market line.     

A Minimizing Risk Strategy for Brazilian Fixed-Income Portfolios

This study presents various risk immunization strategies for fixed-income portfolios, including not only classical measures like duration, convexity, and dispersion but also modern measures such as VaR (value-at-risk) and ES (expected shortfall). Empirical tests are conducted in the Brazilian domestic and international bond market. Because it has had one of highest interest rates since the 1990s, Brazil offers an interesting case study for fixed-income studies. Our results are different for domestic and international bonds. For domestic bonds, using the highest convexity criterion to choose the best portfolio is better than using minimum dispersion, and there is a coincidence between the optimum portfolio selected by the convexity, historical VaR, and ES criteria. For international bonds, our findings indicate that the minimum dispersion strategy performs much better than the maximum convexity strategy. The overall performance of portfolios chosen by minimum VaR and ES criteria is also good, with satisfactory realized returns and squared errors.     

How does the volatility-timing strategy perform in mutual funds portfolios

Literature suggests that a volatility-timing strategy improves the performance of factor portfolios in the stock market and currency carry trade. This paper shows that the performance of this strategy is mixed when applied to mutual fund portfolios. More specifically, its performance not only depends on the investment style of the mutual funds but also the time periods when it is applied.     

COMMENT ON “SKEWNESS‐AWARE ASSET ALLOCATION”

This paper discusses risk measures proposed by Low et al. One of their new risk measures is skewness‐aware deviation, which is closely related to constant absolute risk aversion utility functions. This measure captures downside risk more effectively than traditional variance does. The authors also propose a second measure, skewness‐aware variance, which is derived from skewness‐aware deviation. This measure simplifies asset allocation problems and empirical results indicate that it captures risk better than traditional variance. However, this measure is also found to be inconsistent due to factor selection. Additionally, in the aspect of skewness‐aware deviation, optimal portfolios based upon skewness‐aware variance are sometimes less efficient than optimal portfolios that base themselves on traditional variance.     

Liquidity and macroeconomic management in emerging markets

Emerging markets have received considerable attention for foreign investment and international diversification due to the possibility of higher earnings and a low level of integration with global equity markets. These high returns often need to be balanced by the high liquidity costs of trading in illiquid emerging markets. Several studies have shown that central bank and government policies are significant determinants of market liquidity. We investigate the influence of monetary and fiscal policy variables on the market and firm level liquidity of eight emerging stock markets of Asia. Using four different (il)liquidity measures and nine macroeconomic variables, we find that changes in the money supply, government expenditure and private borrowing significantly affect stock market liquidity. Illiquidity is also strongly affected by the bank rate, short-term interest rate and government borrowing. We demonstrate that ‘crowding out’ and ‘cost of funds’ effects exist in these markets. Other major findings are that some markets are more sensitive to local macroeconomic news than world factors, the impact on size based portfolios largely depends on the instruments used by the central banks and government, the liquidity of the manufacturing sector is affected by changes in any policy variables, financial institutions are only influenced by monetary policy variables, and the service sector is least affected.     

Model-free portfolio theory: A rough path approach

Based on a rough path foundation, we develop a model-free approach to stochastic portfolio theory (SPT). Our approach allows to handle significantly more general portfolios compared to previous model-free approaches based on Föllmer integration. Without the assumption of any underlying probabilistic model, we prove a pathwise formula for the relative wealth process, which reduces in the special case of functionally generated portfolios to a pathwise version of the so-called master formula of classical SPT. We show that the appropriately scaled asymptotic growth rate of a far reaching generalization of Cover's universal portfolio based on controlled paths coincides with that of the best retrospectively chosen portfolio within this class. We provide several novel results concerning rough integration, and highlight the advantages of the rough path approach by showing that (nonfunctionally generated) log-optimal portfolios in an ergodic Itô diffusion setting have the same asymptotic growth rate as Cover's universal portfolio and the best retrospectively chosen one.     

The conflicting impacts of export fluctuations and diversification programmes

Abstract

While analyses of export instability and diversification policies typically focus on aggregate earnings, a conflict can arise between income instability at the aggregate and household levels. Diversification can reduce a country's aggregate income instability and simultaneously increase the instability experienced by many households, and perhaps by every household in the country. We demonstrate how alternative export portfolios can produce this conflict in instability. The conflict means that the conclusions from previous empirical studies need to be qualified and policy recommendations need to be carefully formulated.     

STATIC FUND SEPARATION OF LONG‐TERM INVESTMENTS

This paper proves a class of static fund separation theorems, valid for investors with a long horizon and constant relative risk aversion, and with stochastic investment opportunities. An optimal portfolio decomposes as a constant mix of a few preference‐free funds, which are common to all investors. The weight in each fund is a constant that may depend on an investor's risk aversion, but not on the state variable, which changes over time. Vice versa, the composition of each fund may depend on the state, but not on the risk aversion, since a fund appears in the portfolios of different investors. We prove these results for two classes of models with a single state variable, and several assets with constant correlations with the state. In the linear class, the state is an Ornstein–Uhlenbeck process, risk premia are affine in the state, while volatilities and the interest rate are constant. In the square root class, the state follows a square root diffusion, expected returns and the interest rate are affine in the state, while volatilities are linear in the square root of the state.     

The Performance of European Socially Responsible Funds

Recent years have witnessed an increasing growth in mutual funds that invest according to social criteria. As a consequence, the financial performance of these portfolios has attracted the interest of academics and practitioners. This paper investigates the performance of a sample of socially responsible mutual funds from seven European countries investing globally and/or in the European market. Using unconditional and conditional models, we assess the performance of these funds in comparison to conventional and socially responsible benchmark portfolios. The results show that European socially responsible funds present in general neutral performance in relation to both conventional and socially responsible benchmarks. However, performance estimates seem to be slightly higher when funds are evaluated in relation to socially responsible indices. Our results also show that socially responsible funds are more exposed to conventional than to socially responsible indices. Furthermore, conventional benchmarks are better able to explain fund returns than socially responsible benchmarks. These findings are robust to both unconditional and conditional models of performance. We also observe that conditional models lead to a slight improvement of performance estimates and to the explanatory power of the models, both when conventional and socially responsible benchmarks are considered. This is consistent with most previous empirical findings on conditional performance evaluation. Our results show that investors who wish to hold European funds can add social screens to their investment choices without compromising financial performance.     

The impact of sovereign wealth funds on global financial markets

If sovereign wealth funds act similarly to private investors and thus allocate foreign assets according to market capitalisation rather than liquidity considerations, official portfolios reduce their “bias” towards the major reserve currencies — the US dollar and the euro. As a result, more capital flows “downhill“ from rich to less wealthy economies. In this scenario, the euro area and the United States would be subject to net capital outflows while Japan and the emerging markets would attract net capital inflows. The potential implications of a rebalancing of international capital flows for stock prices, interest rates and exchange rates remain uncertain, however. The authors wish to thank Marcel Fratzscher for excellents comments. The views expressed in this paper are those of the authors and do not necessarily reflect those of the European Central Bank.     

Exploring International Investment Through a Classroom Portfolio Simulation Project

A rapid integration of financial markets has prevailed during the last three decades. Investors are able to diversify investment beyond national markets to mitigate return volatility of a “pure domestic portfolio.” This article discusses a simulation project through which students learn the role of international investment by managing their own portfolios. The article explains the project's investment ground rule, trading requirement, and grading rubric. The students are required to examine many important factors in international business such as currency risks and regional policies. The structure of this project can also be applied to a course involving student-managed investment funds.     

ON PORTFOLIO CHOICE BY MAXIMIZING THE OUTPERFORMANCE PROBABILITY

We consider the problem of optimal portfolio selection for a multidimensional geometric Brownian motion model. We look for portfolios that maximize the probability of outperforming a stochastic benchmark. More specifically, we seek to maximize the decay rate of the shortfall probability and (or) to minimize the decay rate of the outperformance probability in the long run. A simple heuristic enables us to find an asymptotically optimal investment policy. The results provide interesting insights.