Risk forecasting models and optimal portfolio selection

This study analyses, from an investor's perspective, the performance of several risk forecasting models in obtaining optimal portfolios. The plausibility of the homoscedastic hypothesis implied in the classical Markowitz model is dicussed and more general models which take into account assymetry and time varying risk are analysed. Specifically, it studies whether ARCH-type based models obtain portfolios whose risk-adjusted returns exceed those of the classical Markowitz model. The same analysis is performed with models based on the Lower Partial Moment (LPM) which take into account the assymetry in the distribution of returns. The results suggest that none of the models achieve a clearly superior average performance. It is also found that models based on semivariance perform as well as those based on the variance, but not better than, even if the evaluation criterion is based on the Reward-to-Semivariance ratio. When attention turns to the analysis of worst case performance, the results are clearly different. Models which employ LPM with a high degree of risk aversion (n>2) as the risk measure are consistently superior to those which employ a symmetric measure, either homoscedastic or heteroscedastic.     

An algebraic theory of portfolio allocation

Summary. Using group and majorization theory, we explore what can be established about allocation of funds among assets when asymmetries in the returns vector are carefully controlled. The key insight is that preferences over allocations can be partially ordered via majorized convex hulls that have been generated by a permutation group. Group transitivity suffices to ensure complete portfolio diversification. Point-wise stabilizer subgroups admit sectoral separability in fund allocations. We also bound the admissible allocation vector by a set of linear constraints the coefficients of which are determined by group operations on location and scale asymmetries in the rate of returns vector. For a distribution that is symmetric under a reflection group, the linear constraints may be further strengthened whenever there exists an hyperplane that separates convex sets. Received: May 15, 2001; revised version: March 20, 2002 RID="*" ID="*" Journal paper No. J-19797 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3463, and supported by Hatch Act and State of Iowa funds. Correspondence to: D. A. Hennessy     

The effect of inflation uncertainty on inflation: Stochastic volatility in mean model within a dynamic framework

This paper investigates the effect of inflation uncertainty innovations on inflation over time by considering the monthly United States data for the time period 1976–2006. In order to investigate the effect of inflation uncertainty innovation on inflation, a Stochastic Volatility in Mean model (SVM) has been employed. SVM models are generally used to capture the innovation to inflation uncertainty, which cannot be achieved in the framework of popular deterministic ARCH type of models. Empirical evidence provided here suggests that innovations in inflation volatility increases inflation persistently. This evidence is robust across various definitions of inflation and different sub-periods.     

国际投资组合选择理论研究进展

国际投资组合选择理论研究的是在一定的假设条件下,当经济实现均衡时,投资者所应持有的本国与外国金融资产的比例。它的发展有5个特征:从追求金融市场的局部均衡到追求经济的一般均衡;从不考虑投资者的存在到考虑投资者个人效用的最大化;从单纯的理论模型构建到结合现实数据进行实证检验;从假设金融市场完全到考虑金融市场不完全的情况;从假设金融市场一体化到考虑金融市场存在分割的情况。     

Evaluating the impact of inequality constraints and parameter uncertainty on optimal portfolio choice

We present new analytical results for the impact of portfolio weight constraints on an investor’s optimal portfolio when parameter uncertainty is taken into account. While it is well known that parameter uncertainty and imposing weight constraints results in reduced certainty equivalent returns, in the general case, there are no analytical results. In a special case, commonly used in the funds management literature, we derive analytical expression for the certainty equivalent loss that does not depend on the risk aversion parameter. We illustrate our theoretical results using hedge fund data, from the perspective of a fund-of-fund manager. Our contribution is to formalize the framework to investigate this problem, as well as providing tractable analytical solutions that can be implemented using either simulated or asset manager returns.     

On the theory of east-west trade under uncertainty

Taking the final stage of the existing socialist economy as the labormanaged economy, this paper establishes a model of East-West trade between a capitalist economy and a labor-managed economy, both of which face asymmetric technological uncertainty. The model reflects the facts that the securities markets for firms' ownership shares exist only in the capitalist economy and that the firm's objective function in the capitalist economy is different from that in the labor-managed economy. It also considers the existence of international forward markets for commodities as international risk-sharing arrangements. Thus, the paper shows that all the basic theorems in traditional trade theory (Factor Price Equalization, Heckscher-Ohlin, Stolper-Samuelson and Rybczynski) carry over to the uncertain environments characterized by different types of economies.This is the final version of the paper, the first draft of which was presented at the 1987 annual meeting of the Japanese Association of International Economics. An earlier version has recently appeared in my book,Competition, Monopoly and International Trade Under Uncertainty (written in Japanese, Tokyo: Asian Economic New Press 1989). I wish to thank professors H. E. Leland, S. Fujino, H. Eguchi, M. Ohyama, K. Otaka, M. Ogawa, T. Ohsawa, K. Fukao, M. Nishijima and two anonymous referees for their helpful comments. Any remaining errors, however, are my responsibility.     

Oil price uncertainty and the business cycle: Accounting for the influences of global supply and demand within a VAR GARCH-in-mean framework

ABSTRACT

This article reinvestigates the influence of oil price uncertainty on real economic activity in the United States using a four-variable VAR GARCH-in-mean asymmetric BEKK model. In contrast to previous studies in this area, the analysis focuses on business cycle fluctuations and we control for global supply and demand factors that might affect the real price of oil, its volatility as well as the US economy. We find that – even after accounting for these factors – oil price uncertainty still has a highly significant negative influence on the US business cycle. Our computations show that the effect is economically important during several periods, mostly after a significant variance shift in the mid-1980s. We simultaneously estimate the effect on the global business cycle but find that it is comparatively weak. Finally, significant spillover effects in the GARCH model suggest that oil price volatility is a gauge and channel of transmission of more general macroeconomic shocks and uncertainty. These linkages are particularly strong in case of unexpected bad news.     

On the theory of monopolistic competition under demand uncertainty

Establishing a model of a monopolistically competitive industry in which risk-averse Cournot firms act under demand uncertainty and in which the output of individual firms and the number of firms in the industry are both endogenously determined by free entry and exit, this paper attempts to investigate the effects of demand uncertainty on the market equilibrium of a monopolistically competitive industry. It is assumed, for calculus simplification, that the firms are identical in the sense that they have the same monopolistic power and the same production technology. The paper presents some interesting and useful comparative statics results which are contrary to those proposed in the existing papers.This is a revised version of my paper which was firstly presented to the annual meeting of the Japanese Association of International Economics held in 1988 and then included partially in my book published in 1989. I am indebted to professors D. Bös, S. Fujino, M. Ohyama, M. Nishijima, to the members of the Public Economics Research Seminar in Bonn, and to two anonymous referees for their helpful discussions and useful suggestions. Any remaining errors, however, are my responsibility.     

Securitization and regulatory arbitrage within the ABCT framework

This paper discusses the consequences of securitization and how it links to the Austrian Business Cycle Theory (ABCT). The argument that securitization is behind fiduciary credit expansion preceding the 2008 crisis is incomplete. Consolidated balance sheet analysis demonstrates that securitization per se actually sterilizes the inflationary effect of previous fiduciary credits by transforming them into credits backed by voluntary savings. This sterilization stage is subsequently followed by new fiduciary credits issuance as securitization creates excess reserves and excess capital for banks. However, when securitization is used as a tool to implement arbitrage strategies of the Basel prudential rules, it enables banks to create more fiduciary credit while time preference remains unchanged. This creates the conditions for business cycle amplification.     

Optimal output and the theory of the firm under uncertainty

This letter analyzes the sensitivity of the optimal output set by a firm faced by demand uncertainty to changes in the shape of its cost and revenue functions.     

Pastoral economics within the framework of a social economy

Eucken, in his paradigm of a functionally competitive social market economy, established the basis for a free market economy which institutionalizes concerns for economic and social justice. The Bishops’ Pastoral (and also the Lay Letter) on the U.S. economy approach the concept of a social and just economy from a Christian moral tradition. A community of interests between these two approaches, as well as Donaldson’s synthesis of Nozick’s and Rawl’s theories of justice, causes a moral-economic dialogue and cross fertilization to emerge. The Bishops postulate that the evolution of a just and fair market economy, as the guarantor of freedom, human dignity, and justice, cannot be left to chance but needs to be consciously guided. Therefore, they emphasize the integration of economic theories and policies with notions of “fairness” and “justice,” advocating a holistic approach in viewing the economic system as an organic whole. This paper shows that the broad economic guidelines, which Bishops suggest, fall within the framework of a functional market economy, i.e., a social market economy. It does not deal with the religious and biblical arguments of the Pastoral Letter.     

Labor theory of value and the uncertainty in capitalist economy

This article aims to offer a reply to Steedman’s critique of Marx’s labor theory of value. Although this critique having been there for about three decades, the anti-critiques from Marxists are up to date flawed with fatal limitation, losing sight of an important dimension of labor theory of value, i.e., without taking it as a theoretical tool of understanding the uncertainty rooted in capitalist mode of production. The first part of this article reviews the controversy initiated by Steedman. Part 2 discusses Marx’s dual theory of market value and Rubin’s interpretation. Our view is that, if Rubin’s interpretation is accepted, a refutation of Steedman’s critique towards Marx will be impossible. Part 3 of this article explores the possible reconstruction of market value in the perspective of the dynamics in the pivoting of market value. We concludes that, the relationship between the standard condition of production and value is not, as argued by Steedman, of deterministic and one-directional character. For Marx, labor theory of value is applied to analyze the uncertain relation between the means and the end, the condition and the result of capitalist production. Meanwhile, another reply is attempted towards the negative comment on labor theory of value made by contemporary evolutionary economist such as Hodgson. In our view, Marx’s labor theory of value is not irrelevant as claimed by Hodgson to the main topics of evolutionary economics such as variety and “natural selection.” It is through labor theory of value that Marx explains the co-evolution of technology and economy.     

On the theory of the competitive labor-managed firm under price uncertainty

The short-run behavior of a labor-managed firm under competitive assumptions and price uncertainty is analyzed assuming risk aversion. It is compared with its behavior under certainty and the behavior of a capitalist-managed firm under price uncertainty. It is shown that a risk-averse labor-managed firm employs more labor than a risk-neutral labor-managed firm. Generally, uncertainty is seen to have greater impact on the behavior of a labor-managed firm than on the behavior of a capitalist-managed firm. Except under constant risk aversion, the behavior of a labor-managed firm under price uncertainty is less predictable than that of a capitalist-managed firm.