Portfolio optimization under asset pricing anomalies

Fama and French (1993) find that the SMB and the HML factors explain much of the cross-section stock returns that are unexplained by the CAPM, whereas Daniel and Titman (1997) show that it is the characteristics of the stocks that are responsible rather than the factors. But both arguments are largely based only on expected return comparisons, and little is known about how important each of the two explanations matters to an investor's investment decisions in general and portfolio optimization in particular. In this paper, we show that a mean-variance maximizing investor who exploits the asset pricing anomaly of the CAPM can achieve substantial economic gain than simply holding the market index. Indeed, using monthly Japanese data on the first 50 largest stocks over the period 1980–1997, we find the optimized portfolio constructed from characteristics-based model is the best performing one and has monthly returns more than 0.81 percent (10.16 percent annualized) over the Nikkei 225 index with no greater risk.     

THE PRICE OF RISK IN THE SOUTH AFRICAN EQUITY MARKET

This paper investigates domestic risk–return behaviour by focussing on the intertemporal relationship between the conditional domestic equity market premium, its conditional variance and its conditional covariance with the international equity market. The paper finds that the domestic equity market prices in both domestic and international diversification risk. The estimated daily price of domestic variance risk is 0.0279% (EAR: 7.28%) for every one unit of expected domestic variance. The estimated daily price of covariance risk is 0.0111% (EAR: 2.83%) for every unit of expected covariance risk. The representative domestic investor values domestic variance more than covariance risk. The variances of domestic and international equity returns are found to be time‐varying, as is the covariance between the two. Evidence is found that the Johannesburg Securities Exchange is not perfectly integrated with the world economy, in an absolute sense. The volatility spillover effect is observed to be both significant and positive. The standard Capital Asset Pricing Model misspecifies the return to domestic risk, biasing the risk–return coefficient upwards. Domestic investors are rewarded for holding internationally diversified portfolios, with an internationally diversified portfolio expected to have an additional daily return of 0.0238% (EAR: 6.29%) for the same level of risk as an entirely domestic equity portfolio.     

Intertemporal production and asset pricing: a duality approach

This paper analyzes a firm's intertemporal optimization problemunder uncertainty and presents a new asset pricing model fromthe vantage point of the production side of the economy usingthe duality principle. The intertemporal profit-maximizationproblem is formulated using the familiar cost function, andthe production Euler equation that encapsulates the joint behaviorof production and asset returns is derived. An asset's riskis measured by its covariance with the stochastic discount factorrepresented by the ratio of discounted marginal costs. The riskpremium is determined by the conditional covariances of assetreturns with output growth scaled by the degree of scale economiesand with input price changes weighted by the cost share of aninput. The proposed model has the standard structure of a multibetapricing model and suggests four economic risk factors–outputgrowth, the return on human capital, the return on physicalcapital, and technology shocks–for use in empirical analysis.     

The current account as a dynamic portfolio choice problem

The current account can be understood as the outcome of investment decisions made by domestic and foreign investors. These decisions can be decomposed into portfolio rebalancing and portfolio growth components, as highlighted by theoretical models. The empirical literature draws attention to the relative importance of portfolio rebalancing to explain fluctuations in capital flows, although they do not shed light on the mechanisms behind these rebalancing effects. In this paper, we provide empirical evidence of the importance of portfolio rebalancing driven by changes in investment opportunities for the dynamics of the current account. In particular, we evaluate the predictions of a partial-equilibrium model of the current account with dynamic portfolio choices, in which portfolio rebalancing is driven by changes in expected asset returns. Focusing on the dynamics of the current account between Japan and the US, we find evidence supporting innovations in investment opportunities as an important mechanism to explain international capital flows.     

An Empirical Asset Pricing Model Accommodating the Sector-Heterogeneity of Risk

Stock returns are generally difficult to explain, as they are comprised of many discrete channels of risk. Empirical asset pricing models (EAPM), such as the Fama-French five-factor model (FF5), have been used to partition these channels across a series of systematic risk factors, such as company size (total market equity), value (book-to-market ratio), investment, and operating profitability. Prior EAPMs only accounted for how such factors contributed to risk at the market-level, ignoring any potential variation across sector. This study developed a sector-heterogenous model (SHM) which directly accounts for this variation by generalizing the Fama-French methodology to sector-subsets of stocks. The results demonstrated that risk is meaningfully heterogenous across sectors for each of the factors in the FF5, with different subgroups of factors being statistically significant within each sector. In a direct comparison of explanatory power, the SHM outperformed the FF5 and improved adjusted R² by an average of 5% for stocks across all sectors. Several applications of sector-heterogeneity were then demonstrated for stock-picking purposes, including a high-beta portfolio strategy using the SHM-beta which outperformed the S&P 500 in backtesting. This study concludes that meaningful sector-heterogeneity exists in market risk. This information is materially useful to investors.

     

Strategic Asset Allocation for China＇s Foreign Reserves： A Copula Approach

In this paper, we study strategic asset allocation for China＇s foreign reserves using a risk- based approach. Four aspects of the risk management are investigated： an investment universe, dependence structure, allocation strategies under risk minimization and trade-off between risks and returns. A regime-switching copula model is developed to investigate the dynamic dependence between assets. One regime emphasizes a short-term safe asset and the other regime emphasizes a long-term safe asset. The optimal allocation is derived following two strategies： risk minimization and trade-off between risks and returns in utility maximization with disappointment avoidance, lf the central bank focuses solely on risk minimization, the asymmetries in the asset return dependence encourage the flight to safety. However, if higher risks are allowed in exchange for higher returns, even the exchange is very conservative, and the asymmetries would discourage the flight to safety. Therefore, we suggest that China should mitigate its flight to safety after 2008 and increase holdings of short-term bank deposits, long-term treasury bonds and euro bonds.     

UK investment trust portfolio strategies before the First World War†

UK investment trust companies were at the forefront of financial innovation during the so-called first globalization era before the First World War. This study examines their portfolio strategies in detail, using a unique dataset of 115 portfolio observations for 30 different investment trust companies, comprising a total of 32,708 portfolio holdings. Our results reveal strong performance and relatively sophisticated asset management, which was based on a mixture of a buy-and-hold investment strategy and active portfolio management. Investment trusts employed global rather than domestic diversification. The early predominant investment in bonds in the 1880s gradually declined in favour of ordinary and preferred shares. North and Latin American markets were the main geographical target of UK investment trusts, with less appetite for domestic investments and negligible interest in continental European financial securities. There is significant cross-sectional variation in asset allocation between investment trusts; they thus avoided herding behaviour in portfolio choice and developed a wide range of different portfolio strategies.     

Optimal currency shares in international reserves: The impact of the euro and the prospects for the dollar

Foreign exchange reserve accumulation has risen dramatically in recent years. The introduction of the euro, greater liquidity in other major currencies, and the rising current account deficits and external debt of the United States have increased the pressure on central banks to diversify away from the US dollar. A major portfolio shift would significantly affect exchange rates and the status of the dollar as the dominant international currency. We develop a dynamic mean-variance optimization framework with portfolio rebalancing costs to estimate optimal portfolio weights among the main international currencies. Making various assumptions on expected currency returns and the variance–covariance structure, we assess how the euro has changed this allocation. We then perform simulations for the optimal currency allocations of four large emerging market countries (Brazil, Russia, India and China), adding constraints that reflect a central bank's desire to hold a sizable portion of its portfolio in the currencies of its peg, its foreign debt and its international trade. Our main results are: (i) The optimizer can match the large share of the US dollar in reserves, when the dollar is the reference (risk-free) currency. (ii) The optimum portfolios show a much lower weight for the euro than is observed. This suggests that the euro may already enjoy an enhanced role as an international reserve currency (“punching above its weight”). (iii) Growth in issuance of euro-denominated securities, a rise in euro zone trade with key emerging markets, and increased use of the euro as a currency peg, would all work towards raising the optimal euro shares, with the last factor being quantitatively the most important. J. Japanese Int. Economies 20 (4) (2006) 508–547.     

A COMPARISON OF SOUTH AFRICAN HEDGE FUND RISK MEASURES

Although hedge funds have enjoyed unrivalled dominance after years of stellar returns, a combination of low interest rates, sustained economic growth and diminished arbitrage opportunities now threaten them. Distinguishing between funds – an onerous task with notoriously opaque investment strategies – has become paramount in the search for optimal returns. Simple risk and return performance measures cannot cope with the demands of an increasingly complex financial milieu. Interest has thus focused on more effective discriminatory performance measures. The innovative Omega ratio is calculated for South African hedge funds and compared with both Sharpe and Sortino ratios. Omega emerges as the superior measure.     

基于RWCS搜索算法的电网多项目组合投资优化决策研究

电网企业的投资项目数量多、金额大,其投资决策是一项较为复杂的工作,需要权衡很多的影响因素和目标函数,考虑如何进行合理的资金分配。通过引入投资组合优化的概念,以经济效益、安全性和社会性为目标函数,考虑电力需求、可靠性、企业投资能力等约束条件,构建了电网企业多项目组合投资优化决策模型。结合布谷鸟搜索算法(Cuckoo search algorithm,CS)在优化问题中较高的求解性能,利用随机权重(Random Weight,RW)动态优化布谷鸟算法。运用实际的算例,验证该模型方法应用于电网建设项目投资组合决策的可操作性和有效性。     

Volatility Spillovers between the US and China Stock Markets: Structural Break Test with Symmetric and Asymmetric GARCH Approaches

Abstract

The paper examines the short-run spillover effects of daily stock returns and volatilities between the Standard & Poor's (S&P) 500 stock index in the US and the Shanghai Stock Exchange (SSE) index in China. First, we find that a structural break occurred in the SSE stock return mean in December 2005. Second, by analyzing modified general autoregressive conditional heteroscedasticity (GARCH)(1,1)-M models, we find evidence of a symmetric and asymmetric volatility spillover effect from the US to the China stock market in the post-break period. Third, we observe the symmetric volatility spillover effect from China to the US in the post-break period.     

Economic policy uncertainty and firm’s cash holding in China: The key role of asset reversibility

This paper investigates how asset reversibility affects the sensitivity of firm’s cash holding to economic policy uncertainty in China. Using the 2012 national input-output table for 139 industries, we measure the industry-level asset reversibility and match them with nonfinancial publicly listed firms over 2007−2017. The results show that asset reversibility has a significant and negative effect on the positive uncertainty-cash holding sensitivity, especially for firms with more severe financial constraints. Furthermore, we find that firms with higher asset reversibility invest more in fixed assets, suggesting that real investment is an important mechanism. In addition, baseline results are robust to potential endogeneity and alternative measures of asset reversibility and economic policy uncertainty. Our findings reveal that asset market friction is a critical determinant of firm’s cash holding.     

直觉模糊多目标证券投资组合决策

针对证券投资产品收益的直觉模糊不确定性,运用直觉模糊数来弹性评估投资产品预期收益,并通过直觉模糊可能性均值和方差来度量投资组合收益和风险。接着基于投资组合收益最大和风险最小及信息熵最小等多个目标构建一个新的直觉模糊投资组合决策模型,进而再运用线性加权方法将其转化为单目标模型来快速获取最优投资组合策略。最后通过真实股票投资实例表明该投资组合模型方法的有效性,且投资者可根据不同目标偏好适时调整优化投资策略。     

Can Employee Stock Options Contribute to Less Risk-Taking?

The executive compensation literature presumes that shareholders offer risk-averse managers stock options to entice them to take on more risk, resulting in riskier investment decisions and thus a greater return on investment. However, recent empirical work challenges this assumption, and theoretical research even argues that high levels of option-based compensation for generally under-diversified managers may actually lead to greater risk aversion. We evaluate the incentive structure of employee stock options by examining the level of R&D investment and the return on that investment conditional on the portfolio “vega,” which captures the sensitivity of option value to stock price volatility. Our results suggest that both investment in R&D and the return on R&D, as measured by future earnings and patent awards, varies concavely with vega. That is, low to moderate levels of vega correspond to increasing investment in and returns on R&D, consistent with vega inducing more profitable investments, but marginal returns decline as vega increases. Collectively, these results, bolstered by several supplemental analyses, suggest that this surprising relation between vega and risky investment is driven by greater risk aversion at higher levels of vega. Overall, our results imply that employee stock options may not always align the incentives of managers and shareholders.     

The Incidence of Deficit Finance with Imperfect Capital Markets

The purpose of this paper is to examine the possible differential welfare implications of deficit finance using a portfolio allocation model. To analyze the incidence of changing the time path of taxation in an economy with heterogeneous agents, I develop a two-period, general equilibrium extension of work done previously to analyze the effects of taxation on risk-taking at the individual level. Constraints on short sales of assets are introduced, and fiscal policy, changing the timing of taxation, will indirectly determine which of these constraints bind as well as alter relative tax burdens. Changes in the timing of a flat-rate tax will also alter equilibrium asset returns, and because preferences are such that agents differ in their tolerance of risk, a Pareto frontier can be derived over a range of different levels of deficit finance.     

Evaluating the performance of futures hedging using multivariate realized volatility

This paper investigates the performance of a conditional hedging model using the realized covariance measure (RCM) with noisy high-frequency data. We employ a bivariate realized exponential GARCH (BREG) model with some RCMs to estimate conditional optimal hedge ratios in the Japanese stock and futures markets. The bivariate Student’s t-distribution as well as the bivariate normal distribution are used for the return distribution. The out-of-sample results show that the BREG model outperforms the DCC-EGARCH model and the OLS approach using daily returns for a short hedge in the period without unpredictably large fluctuations in returns such as the Lehman aftermath and the economic impact of the Great East Japan Earthquake. The BREG model with a Student’s t-distribution is likely to be superior to that with a normal distribution. The use of RCMs with methods reducing bias induced by microstructure noise and non-synchronous trading improves the performance. We also find that the joint model of returns and RCM such as the BREG model yields better performance for a short hedge than a model in which RCM is included as an exogenous variable.     

APPLYING A GENETIC ALGORITHM TO INTERNATIONAL DIVERSIFICATION OF EQUITY PORTFOLIOS: A SOUTH AFRICAN INVESTOR PERSPECTIVE

This paper uses the genetic algorithm (GA) approach to generate a portfolio optimisation scenario of a South African investor who seeks to maximise return from investing in S&P500, FTSE100, NASDAQ, DOWJONES, CAC40 and the DAX from January 1, 2005, to January 31, 2008, but facing exchange rate risk. The GA searches for the optimal solution in the entire set of financial constraints without looking for partial derivatives of the utility function. Whereas most financial problems require a non‐linear and time‐varying model, the GA, with its survival principle of offspring chromosomes, is better suited to this type of problem than local optimisation methods. The performance of the GA is compared with two non‐linear models, namely the quadratic mean‐variance (QMV), which maximises the portfolio mean‐variance, and the quadratic variance minimisation (QVM), which minimises the portfolio variance. The results show that neither the QMV nor the QVM takes into account the domestic investors' risk attitude towards investing in foreign equities and therefore does not provide any international diversification benefits. In addition, the bootstrapping scenario of 10,000 simulations reveals that neither the QMV nor the QVM outperforms the GA in terms of Sharpe ratio and flexibility in dealing with investors' risk attitude towards investing in foreign equities denominated in foreign currencies.     

Historical returns and security market development, 1872–1925

Annual holding returns are reported for a broad range of the assets available to investors in the security market between 1872 and 1925. A generally favorable picture of asset performance is revealed when these returns are compared to those on similar investments in the modern era. Two changes in the patterns of returns around 1900 occurred—a decline in inflation adjusted debt returns and an increase in the volatility of stock returns (especially industrial stock). The structure of asset returns after 1900 was distinctly modern and has persisted to the present. The emergence of the modern structure of returns is linked to institutional changes in the security market between 1890 and World War I, and to the process of industrial capital formation.     

Evaluating mutual fund performance in an emerging Asian economy: The Malaysian experience

This paper examines the performance of 311 mutual funds from January 1990 to December 2005 in Malaysia by using composite portfolio performance measures, the single market model, the Fama and French three-factor model, and the Carhart four-factor model across investment horizons. Overall, we have found evidence that mutual fund performances yield superior returns with relatively lower systematic risks. A 3-year investment appears to be the preferred investment horizon with the highest annualized returns of 9.23%. The results of the single market model, the Fama–French three-factor model, and the Carhart four-factor model have all indicated that beta, size, book-to-market value, and momentum factors are significant factors in explaining equity fund returns with the Carhart four-factor model being the relatively better model among the three. The beta factor has demonstrated the highest coefficient and significance. The results further indicate that the average equity funds in Malaysia hold smaller market capitalization stocks and value oriented stocks, as well as buying past-winning and selling past-losing stocks.     

基于遗传算法的组合证券投资决策

针对均值-VaR模型,引入随机全局搜索的遗传算法求解资产配置比例。以中证指数公司发布的HS300行业分类指数构建投资组合,分析了行业资产配置的投资组合问题,并对投资组合特征关于显著性水平α及风险偏好系数δ进行灵敏度分析。实证分析结果表明,本文所设计的算法取得了良好的效果,解出的结果既满足了投资的目标和约束条件,又反映了不同投资者之间不同的收益风险需求,而且具有较好的实践性。