VaR约束与资产配置优化——基于中国证券市场的经验数据分析

VaR模型是一种有效的风险计量和管理工具。在假设组合收益服从正态分布的条件下,分析了引入VaR约束的均值一方差模型及有效边界;考虑在一定置信水平下。结合组合收益的实际分布,给出了满足投资者VaR约束下期望收益最大化的计量模型及投资策略选择,并利用中国证券市场数据进行了实证研究。     

Synchronization and diversity in business cycles: a network analysis of the European Union

In this article, we use a correlation matrix and its internal networks to analyse business cycle synchronization across Europe since 2000. This methodology allows us to summarize individual country interactions and co-movements while also capturing the existing heterogeneity of connectivity within the European economic system. Our results indicate that synchronization of the euro zone countries remained stable from 1999 until the current financial crisis, after which co-movements increased sharply and synchronization rose to the highest in the time sample. By endogenously identifying clusters of countries with close connections in their business cycle, we also refute the commonly accepted notion of identifiable core and peripheral euro zone countries.     

Identifying reference companies using the book-to-market ratio: a minimum spanning tree approach

There is substantial evidence to suggest that the book-to-market (BM) ratio is an important factor in explaining stock market returns. Its role has proved difficult to isolate, however, due to statistical problems in its construction and to its observational equivalence to a number of risk and behavioural explanations. In addition, now widely recognised complex behaviour in financial markets has called into question modelling approaches that are limited in their ability to uncover relationships that are possibly masked during financial crises, for example. As one response, our research explores the value of a newly applied technique which examines the topological properties of minimum spanning trees as applied to both the BM ratio and market returns. Our intention is to identify and report investment signals as determined by the BM ratio and to assess the relationships of these signals to returns outcomes. The approach enables highly nonlinear behaviour to be addressed and the relationships we set out to capture to be reported in novel ways. We motivate and evidence a previously unreported role for BM as an investment signal which is effective over varying stock market conditions, including the financial crisis that began in 2008.     

考虑均值—方差多目标决策的报童模型研究

考虑到传统报童模型忽视了对风险的关注,引入了方差来度量报童面临的风险,从而将报童的期望利润最大化的单目标决策问题扩展为均值-方差多目标决策问题。首先利用绝对最优解和有效解的概念分析了多目标决策问题的相关性质,然后利用加权法将其转化为单目标决策问题进行求解,最后通过数值实验研究了权系数和需求波动对报童最优订货量的影响。     

ENHANCEMENT OF THE APPLICABILITY OF MARKOWITZ'S PORTFOLIO OPTIMIZATION BY UTILIZING RANDOM MATRIX THEORY

The traditional estimated return for the Markowitz mean-variance optimization has been demonstrated to seriously depart from its theoretic optimal return. We prove that this phenomenon is natural and the estimated optimal return is always       times larger than its theoretic counterpart, where       with  y  as the ratio of the dimension to sample size. Thereafter, we develop new bootstrap-corrected estimations for the optimal return and its asset allocation and prove that these bootstrap-corrected estimates are proportionally consistent with their theoretic counterparts. Our theoretical results are further confirmed by our simulations, which show that the essence of the portfolio analysis problem could be adequately captured by our proposed approach. This greatly enhances the practical uses of the Markowitz mean-variance optimization procedure.     

基于余弦相似度(CS)和最小生成树(MST)的基金市场复杂网络研究

以中国基金市场中123家基金公司持有的投资组合为样本,综合运用余弦相似度(CS)和最小生成树(MST)方法,考量基金市场复杂网络。结果显示:各家基金公司持有股票组合的相似程度比持有债券组合的相似程度更高,表明他们持有的债券组合较之股票组合更加多元化,基金公司持有的股票相对集中于市值大、成长性高的公司。同时,全部资产投资组合、股票投资组合和债券投资组合等三类基金MST网络的节点度均服从幂律分布,表明大多数基金公司以少数强影响力基金公司为中心聚集起来,彼此之间具有较强的业务关联。此种网络结构特征可能导致市场风险向基金聚集团体集中,其抵御系统性风险的能力偏弱,也不利于满足投资者的理财多元化需求。     

Incorporating time-varying jump intensities in the mean-variance portfolio decisions

This paper examines the role of time-varying jump intensities in forming mean-variance portfolios. We find that compared with the no-jump or constant-jump models, the model which incorporates time-varying jump intensities better fits the dynamics of the assets returns, and yields mean-variance portfolios with higher Sharpe ratios. Our research suggests that using a better econometric model that captures non-normal features in the data has benefits for portfolio allocation even for a mean-variance investor.     

On statistical inference on the mean-variance efficient set

A proof of the asymptotic distribution of the estimated mean-variance frontier is given. A Bayesian prediction interval is derived for the capital asset pricing model. Numerical illustrations show that the prediction intervals for the CAPM are smaller than those for the constant mean model, if the fit of the CAPM is better than that of the constant mean model.     

An improved spanning tree approach for the reliability analysis of supply chain collaborative network

A higher degree of reliability in the collaborative network can increase the competitiveness and performance of an entire supply chain. As supply chain networks grow more complex, the consequences of unreliable behaviour become increasingly severe in terms of cost, effort and time. Moreover, it is computationally difficult to calculate the network reliability of a Non-deterministic Polynomial-time hard (NP-hard) all-terminal network using state enumeration, as this may require a huge number of iterations for topology optimisation. Therefore, this paper proposes an alternative approach of an improved spanning tree for reliability analysis to help effectively evaluate and analyse the reliability of collaborative networks in supply chains and reduce the comparative computational complexity of algorithms. Set theory is employed to evaluate and model the all-terminal reliability of the improved spanning tree algorithm and present a case study of a supply chain used in lamp production to illustrate the application of the proposed approach.     

Mean–variance dominant trading strategies

The paper examines the relative importance of ten anomaly-based trading strategies. We employ Mean Variance spanning methodologies in a classical unconditional setting and a novel conditional setting. Fixed-weight optimal portfolios stemming from the unconditional methodology indicate that all the strategies are needed to enhance the mean–variance tradeoff. This conclusion is completely reversed when we allow for time-varying portfolio weights as a nonlinear function of lagged economic indicators. The overall results suggest that diversified anomaly-based holdings are of limited benefit to sophisticated investors who employ dynamic trading strategies.