The parameterized upper and lower triangular splitting methods for saddle point problems

Complex moment-based eigensolvers for solving interior eigenvalue problems have been studied because of their high parallel efficiency. Recently, we proposed the block Arnoldi-type complex moment-based eigensolver without a low-rank approximation. A low-rank approximation plays a very important role in reducing computational cost and stabilizing accuracy in complex moment-based eigensolvers. In this paper, we develop the method and propose block Krylov-type complex moment-based eigensolvers with a low-rank approximation. Numerical experiments indicate that the proposed methods have higher performance than the block SS–RR method, which is one of the most typical complex moment-based eigensolvers.     

Moment information for probability distributions,without solving the moment problem,II: Main-mass,tails and shape approximation

How much information does a small number of moments carry about the unknown distribution function? Is it possible to explicitly obtain from these moments some useful information, e.g., about the support, the modality, the general shape, or the tails of a distribution, without going into a detailed numerical solution of the moment problem? In this, previous and subsequent papers, clear and easy to implement answers will be given to some questions of this type. First, the question of how to distinguish between the main-mass interval and the tail regions, in the case we know only a number of moments of the target distribution function, will be addressed. The answer to this question is based on a version of the Chebyshev–Stieltjes–Markov inequality, which provides us with upper and lower, moment-based, bounds for the target distribution. Then, exploiting existing asymptotic results in the main-mass region, an explicit, moment-based approximation of the target probability density function is provided. Although the latter cannot be considered, in general, as a satisfactory solution, it can always serve as an initial approximation in any iterative scheme for the numerical solution of the moment problem. Numerical results illustrating all the theoretical statements are also presented.     

Strategies for computation of compound distributions with two-sided severities

The recursive scheme proposed by Panjer for the computation of discrete compound distributions whose counting distributions are Binomial, Poisson, or Pascal provides an extremely efficient alternative to an important actuarial problem where brute-force convolution methods or moment-based approximations are unsatisfactory. However, the scheme fails in the important case where the counts are Pascal and the severities are two-sided. As research is currently underway on this problem, the authors intend to present computational results on the following approaches: (1) iterative use of Panjer's formula: (2) approximation by splitting of positive and negative components: (3) use of analytically-derived tail approximations.     

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In this paper, we consider the estimation problem for partially linear models with additive measurement errors in the nonparametric part. Two kinds of estimators are proposed. The first one is an integral moment-based estimator with deconvolution kernel techniques, associated with the strong consistency for the estimator. Another one is a simulation-based estimator to avoid the integrals involved in the integral moment-based estimator. Simulation studies are conducted to examine the performance of the proposed estimators.     

Portfolio Improvement by Using the Sharpe Rule and Value-at-Risk

This study discusses the applications of the Sharpe rule in portfolio measurement and management. It proposes that a portion of the portfolio value should be invested in some other assets for portfolio improvement. By applying the Sharpe rule, it can be determined that new stocks are worthy of adding to the old portfolio if they satisfy a condition, in which the average return rate of these stocks is greater than the return rate of the old portfolio multiplied by the sum of the elasticity of the VaR and 1. One attraction of our approach is diversification. A numerical example in the Hong Kong stock market is presented for illustration. Some experimental results show that a new portfolio with the 'highest' Sharpe ratio can be obtained by adding only a few new assets. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于VaR和ES调整的Sharpe比率及在基金评价中的实证研究

传统Sharpe比率将投资收益的标准差作为风险的度量,而实证研究中更关注基金的损失风险而非全部风险,这是收益标准差所无法准确刻画的。针对传统Sharpe比率的这一缺点,本文考虑了用于度量下方风险的指标风险价值VaR(Value at Risk)和预期不足ES(Expected Shortfall)来替代投资收益的标准差,从而对传统Sharpe比率进行了调整。这里对VaR和ES进行计算时,运用了经验非参数估计和非参数平滑核估计两种方法。此外,本文还考虑了基金收益随时间波动的动态性,用广义自回归异方差GARCH模型对收益波动进行模拟,考察动态的VaR和ES,在实践中以动态的VaR和ES评价风险收益更加灵活。在实证研究中,本文用传统的Sharpe比率、基于VaR和ES的Sharpe比率以及基于条件VaR和条件ES的条件Sharpe比率对国内证券市场上所有26只封闭式基金在2005-2009年间的业绩进行了实证分析,分析了基金在不同指标下所体现的风险控制能力和收益水平的差别,并基于不同指标对所有基金进行了排名。此外,本文还运用协整检验考察基金收益率与市场基准指数是否存在联动关系,检验证明两者并不存在长期的均衡关系。     

Polynomials orthogonal with respect to cardinal B-spline weight functions

A stable and efficient discretization procedure is developed to compute the recurrence coefficients for orthogonal polynomials whose weight function is a polynomial cardinal spline of order m ≥ 1. The procedure is compared with a symbolic moment-based method developed recently by G. V. Milovanovi?. Numerical examples are provided for illustration.     

An improved high order moment-based saddlepoint approximation method for reliability analysis

Moment-based methods use only statistical moments of random variables for reliability analysis. The cumulative distribution function (CDF) or probability density function (PDF) of a performance function can be constructed from the perspective of the first few statistical moments, and the failure probability can be evaluated accordingly. However, existing moment-based methods may lead to large errors or instability. As such, the present paper focuses on the high order moment method for higher accuracy of reliability estimation by combining the common saddlepoint approximation technique, and an improved high order moment-based saddlepoint approximation (SPA) method for reliability analysis is presented. The approximated cumulant generating function (CGF) and the CDF of the performance function in terms of its first four statistical-moments are constructed. The developed method can be used for reliability evaluation of uncertain structures follow any types of distribution. Several numerical examples are given to demonstrate the efficacy and accuracy of the proposed method. Comparisons of the new method and several existing high order moment methods are also made on the reliability assessment.     

基金业绩评估方法

本文介绍了普通Sharpe指数和瞬时Sharpe指数的概念，我们分析了它们之间的关系，并通过实证研究,我们认为瞬时厦普指数更能反映基金实际水平。     

The equity risk premium and the riskfree rate in an economy with borrowing constraints

Our objective is to study analytically the effect of borrowing constraints on asset returns. We explicitly characterize the equilibrium for an exchange economy with two agents who differ in their risk aversion and are prohibited from borrowing. In a representative-agent economy with CRRA preferences, the Sharpe ratio of equity returns and the riskfree rate are linked by the risk aversion parameter. We show that allowing for preference heterogeneity and imposing borrowing constraints breaks this link. We find that an economy with borrowing constraints exhibits simultaneously a relatively high Sharpe ratio of stock returns and a relatively low riskfree interest rate, compared to both representative-agent and unconstrained heterogeneous-agent economies.      

Target Identification Using Dictionary Matching of Generalized Polarization Tensors

The aim of this paper is to provide a fast and efficient procedure for (real-time) target identification in imaging based on matching on a dictionary of precomputed generalized polarization tensors (GPTs). The approach is based on some important properties of the GPTs and new invariants. A new shape representation is given and numerically tested in the presence of measurement noise. The stability and resolution of the proposed identification algorithm is numerically quantified. We compare the proposed GPT-based shape representation with a moment-based one.     

单形深度中位数在封闭式基金排名中的应用

本文介绍了单形深度函数理论,通过改进夏普指数公式,利用单形深度函数中位数稳健性的特点,将单形深度函数中位数应用于改进的夏普指数公式,对国内的封闭式基金进行了排名与评级,并将其与中信星级和样本星级进行了对比.最后,通过定义基金业绩偏离度提出将其用于评价基金捕捉市场机遇的能力的观点.     

Mean–variance optimal portfolios in the presence of a benchmark with applications to fraud detection

We first study mean–variance efficient portfolios when there are no trading constraints and show that optimal strategies perform poorly in bear markets. We then assume that investors use a stochastic benchmark (linked to the market) as a reference portfolio. We derive mean–variance efficient portfolios when investors aim to achieve a given correlation (or a given dependence structure) with this benchmark. We also provide upper bounds on Sharpe ratios and show how these bounds can be useful for fraud detection. For example, it is shown that under some conditions it is not possible for investment funds to display a negative correlation with the financial market and to have a positive Sharpe ratio. All the results are illustrated in a Black–Scholes market.     

Portfolio performance measurement using differential evolution

The basic problem in finance theory is the selection of an appropriate mix of assets in a portfolio in order to maximize portfolio expected return and subsequently to minimize portfolio risk. Another approach takes into account portfolio performance expressed by various measurement techniques e.g. Sharpe ratio, Treynor ratio, Jensen’s alpha, Information ratio, Sortino ratio, Omega function and Sharpe Omega ratio that are focused on determine the allocation of the available resources in the selected group of assets. This paper presents the alternative approach computing the weights of assets in portfolio assets based on the nonlinear measure techniques: Sortino ratio and Omega function. The proposed alternative includes principle of differential evolution from the group of evolutionary techniques. The experiments are set up on assets included in Dow Jones Industrial Average. Presented original approach enables using also other evolutionary algorithms in the area of portfolio selection based on different measurement techniques.     

Optimal asset allocation aid system: From “one-size” vs “tailor-made” performance ratio

Optimal asset allocation well-fitting investors’ goals is a pressing challenge in risk management. Making a step forward to the Sharpe ratio, the parameter-dependent Sortino–Satchell, Generalized Rachev and Farinelli–Tibiletti performance ratios are suggested for personalizing asset allocation. Tailor-made optimal asset paths for five different investor risk profiles are traced over a rolling 12 month investing horizon. Our simulations show a satisfactorily good match between asset allocation and correspondent risk profile. Specifically, Generalized Rachev ratios outperform in personalized allocation for “extreme” risk profiles, i.e. conservative and aggressive investors, whereas Sortino–Satchell and Farinelli–Tibiletti ratios for those that are more moderate. Sharpe ratio confirms its ability in constructing steady-diversified portfolios, although underperformed.     

Pricing life insurance under stochastic mortality via the instantaneous Sharpe ratio

We develop a pricing rule for life insurance under stochastic mortality in an incomplete market by assuming that the insurance company requires compensation for its risk in the form of a pre-specified instantaneous Sharpe ratio. Our valuation formula satisfies a number of desirable properties, many of which it shares with the standard deviation premium principle. The major result of the paper is that the price per contract solves a linear partial differential equation as the number of contracts approaches infinity. One can represent the limiting price as an expectation with respect to an equivalent martingale measure. Via this representation, one can interpret the instantaneous Sharpe ratio as a market price of mortality risk. Another important result is that if the hazard rate is stochastic, then the risk-adjusted premium is greater than the net premium, even as the number of contracts approaches infinity. Thus, the price reflects the fact that systematic mortality risk cannot be eliminated by selling more life insurance policies. We present a numerical example to illustrate our results, along with the corresponding algorithms.     

Sensitivity analysis for marked Hawkes processes: application to CLO pricing

This paper deals with a model for pricing Collateralized Loan Obligations, where the underlying credit risk is driven by a marked Hawkes process, involving both clustering effects on defaults and random recovery rates. We provide a sensitivity analysis of the CLO price with respect to the parameters of the Hawkes process using a change of probability and a variational approach. We also provide a simplified version of the model where the intensity of the Hawkes process is taken as the instantaneous default rate. In this setting, we give a moment-based formula for the expected survival probability.     

Sharpe thinking in asset ranking with one-sided measures

If we exclude the assumption of normality in return distributions, the classical risk–reward Sharpe Ratio becomes a questionable tool for ranking risky projects. In line with Sharpe thinking, a general risk–reward ratio suitable to compare skewed returns with respect to a benchmark is introduced. The index includes asymmetrical information on: (1) “good” volatility (above the benchmark) and “bad” volatility (below the benchmark), and (2) asymmetrical preference to bet on potential high stakes and the aversion against possible huge losses. The former goal is achieved by using one-sided volatility measures and the latter by choosing the appropriate order for the one-sided moments involved. The Omega Index (see [Cascon A., Keating, C., Shadwick, W., 2002. Introduction to Omega, The Finance Development Centre]) and the Upside Potential Ratio (see [Sortino, F., Van Der Meer, R., Plantinga, A., 1999. The Dutch triangle. Journal of Portfolio Management, 26 (I, Fall), 50–58]) follow as special cases.     

对证券投资基金业绩评价指标间关系的分析

本文采用数理方法,对基金业绩评价中主要使用的特雷诺指数、夏普指数、詹森指数、M2指数进行了分析,从各个指标的基本原理出发,用数学方法推导了相互之间的异同关系,并且阐述了在进行基金业绩评价时的各个指标的使用条件.     

Hedging life insurance with pure endowments

We extend the work of Milevsky et al., [Milevsky, M.A., Promislow, S.D., Young, V.R., 2005. Financial valuation of mortality risk via the instantaneous Sharpe ratio (preprint)] and Young, [Young, V.R., 2006. Pricing life insurance under stochastic mortality via the instantaneous Sharpe ratio (preprint)] by pricing life insurance and pure endowments together. We assume that the company issuing the life insurance and pure endowment contracts requires compensation for their mortality risk in the form of a pre-specified instantaneous Sharpe ratio. We show that the price P^m,n for m life insurances and n pure endowments is less than the sum of the price P^m,0 for m life insurances and the price P^0,n for n pure endowments. Thereby, pure endowment contracts serve as a hedge against the (stochastic) mortality risk inherent in life insurance, and vice versa.