The time-varying effect of monetary policy in China

A sound understanding of monetary transmission mechanism is valuable because it helps the central bank to determine the proper course of monetary policy to balance growth and inflation. As China’s domestic financial markets deepen and develop further towards a market-based system, the country’s monetary policy instrument and transmission should continue to improve for managing economic conditions. Using a short-term key interest rate as standard monetary policy tool and time-varying parameter techniques, this study empirically demonstrates that China’s monetary policy framework is in the midst of transitioning to a market-based approach.     

基于Copula-GARCH对上证和深证的相关性分析

文章首先利用GARCH模型,估计出单个资产收益率在将来某个时刻的条件概率分布;其次,运用Copula理论,构造出Copula函数,刻画投资组合中不同资产间的相关结构,得到两个资产的联合分布;最后应用Copula-GARCH模型对上证综指和深证成指的相关性进行分析。     

中国能源需求的估计与预测模拟

本文模拟了1953-2005年间中国的能源需求函数，并在模拟基础上进行预测分析。研究结果表明：20世纪80年代以后，中国的能源使用效率明显提高，但中国的能源使用效率对能源需求的影响小于国民收入对能源需求的影响；另外，中国人口也是影响能源需求的一个显著因素，能源价格对能源需求的影响不显著；最后，在对中国长期能源需求进行了预测和模拟的基础上为中国未来一段时期内减缓能源需求增长提出了政策建议。     

Re-Examining Variance-Bounds Tests for Asset Prices

The hypothesis of market efficiency is typically rejected by standard variance-bounds tests which assume stationary asset prices. A number of researchers, however, argue that tests used in previous studies are inappropriate since asset prices appear to be generated by nonstationary processes. In this paper, we propose a regression-based variance-bounds test that is valid when the asset price is an integrated process. We apply this test to annual U.S. data over the 1889 to 1985 sample period using measures of the perfect-foresight price constructed from a nonlinear asset-pricing equation that allows for a stochastic discount parameter. The results suggest that the data appear consistent with a version of the efficient-market hypothesis detailed in this paper.     

Evolving Market Efficiency with an Application to Some Bulgarian Shares

With new technically advanced methods and computers at our disposal, the efficient market hypothesis is once again being debated. At the same time, we are witnessing an unprecedented growth in both existing and new financial markets. These new markets are often in economies which have just recently embraced free market economics; we term these stock markets infant markets. Such stock markets are obviously not efficient in allocating the supply of savings to productive capital. We do not test whether or not these infant markets are informationally efficient, but instead examine whether and how they are becoming more efficient. We propose modelling the excess returns of individual securities using a multi-factor model with time-varying coefficients and generalised auto-regressive conditional heteroskedastic (GARCH) errors. If the markets are becoming more informationally efficient or the agents are learning, we would expect this to manifest itself as the time-varying coefficients becoming more stable as time increases. We test our model using data on four Bulgarian shares. First, we estimate an AR(2) model and a GARCH-M(1,1) model for the shares. Then, we estimated our AR(2) model with time varying coefficients and GARCH type errors. We find varying levels of efficiency and varying speeds of movement towards efficiency within our sample of four shares. This revised version was published online in July 2006 with corrections to the Cover Date.     

我国股市行业时变β系数研究

本文主要考察了我国股市13个行业的β系数及信息的影响。研究发现市场信息和行业信息对β系数都有影响,但影响的方向和大小因行业而异。进而对这些行业的β系数的信息非对称效应产生原因进行考察。仅有部分行业的β系数的信息非对称效应可由市场利空消息或行业利空消息解释。     

变时滞循环神经网络模型的全局指数稳定性

利用Brouwer不动点定理，推广的Halanay时延微分不等式及Dini导数，讨论了具有变时滞循环神经网络模型的平衡点的存在性和全局指数稳定性，在不要求激活函数连续可导的条件下，得到了非常简单实用的判别条件。     

SAD效应：一个基于时变风险价格的条件CAPM的解释

很多实证研究都证明季节性情绪混乱(SAD)与股指收益有明显联系。本文研究了这种SAD效应能否用一个包含允许时间变化的风险价格的资产定价模型去捕捉它的存在。本文利用上证综指的日收盘数据得到的初始和超额收益率以及SAD和FALL变量,利用修正的GRACH-M模型进行了分析,认为条件CAPM可以捕捉SAD效应。这与由于日照时间变化而导致的投资者风险承受能力变化进而影响收益的认识相符合。     

The Effect of Regulatory Announcements on the Cost of Equity Capital of British Telecom

This paper examines the impact of regulatory announcements which affect competition, pricing policy and the supply of services in the telecommunications industry on British Telecom's (BT) systematic risk, as measured by the beta coefficient of a market model. Changes in investors' perception of a company's systematic risk will of course also change its cost of equity capital. Since BT's beta coefficient is found to be unstable over the estimation period, the market model is estimated using a time-varying parameter model. The results suggest that announcements which allow the price of BT's services to increase and announcements affecting its supply of services are likely to have an impact on BT's cost of equity capital, since they affect the investor's perception of BT's systematic risk. However, our analysis does not detect any effect from the other types of announcements tested. Further examination of the individual announcements included in the groups reveals that, within the non-significant groups, many individual announcements are significant, but they affect beta in opposite directions and thus no prediction can be made on the sign of their aggregated impact. These findings suggest that when one company dominates the industry, such as in the case of the UK telecommunications industry, the actions of the regulator do not always have the expected effect and problems of regulatory capture are likely to be present.     

Portfolio optimization with CVaR under VG process

Formal portfolio optimization methodologies describe the dynamics of financial instruments price with Gaussian Copula (GC). Without considering the skewness and kurtosis of assets return rate, optimization with GC underestimate the optimal CVaR of portfolio. In the present paper, we develop the approach for portfolio optimization by introducing Lévy processes. It focuses on describing the dynamics of assets’ log price with Variance Gamma copula (VGC) rather than GC. A case study for three Indexes of Chinese Stock Market is performed. On application purpose, we calculate the best hedge positions of Shanghai Index (SHI), Shenzhen Index (SZI) and Small Cap Index (SCI) with the performance function CVaR under VG model. It can be combined with Monte Carlo Simulation and nonlinear programming techniques. This framework is suitable for any investment companies.