VaR的计算方式及其回测检验——基于计算机产业股票的实证研究

VaR自上个世纪90年代起,已经成为了主流的度量风险的方式,但是,VaR模型的计算方式有十多种,哪一种VaR模型是最优模型,甚至于构建什么样的比较框架才能选择出最优模型,仍然没有一个统一的标准。采取比较主流的方式对VaR在股票中的计算以及对VaR模型的回测,是呈现VaR作为现阶段最为流行的风险度量工具的计算和回测检验的方式。     

Quality and Welfare in a Mixed Duopoly with Regulated Prices: The Case of a Public and a Private Hospital

Abstract. Hospital markets are often characterized by price regulation and the existence of different ownership types. Using a Hotelling framework, this paper analyses the effect of heterogeneous objectives of hospitals on quality differentiation, profits and overall welfare in a price‐regulated duopoly with exogenous symmetric locations. In contrast to other studies on mixed duopolies, this paper shows that, in this framework, privatization of the public hospital may increase overall welfare. This holds if the public hospital is similar to the private hospital or less efficient and competition is low. The main driving force is the single‐regulated price which induces under‐provision (over‐provision) of quality of the more (less) efficient hospital compared with the first best. However, if the public hospital is sufficiently more efficient and competition is fierce, a mixed duopoly outperforms both a private and a public duopoly due to an equilibrium price below (above) the price of the private (public) duopoly. This medium price discourages over‐provision of quality of the less efficient hospital and – together with the non‐profit objective – encourages an increase in quality of the more efficient public hospital.     

转型期地方政府重叠利益行为模式研究——以房地产调控为例

转型期中国地方政府行为模式较为复杂,可以用重叠利益行动结构进行解释.地方政府多样化的行为表现,源自于其行为的利益归属区间的不同.在房地产调控领域,由于地方政府主要是根据自己的利益需要和本地区具体情况,按照重叠利益结构原理,对调控措施进行了巧妙的选择,结果保证了地方政府利益最大化,但未实现公共利益最大化.在公众无实质性制衡权力的情况下,改变地方政府行为模式的主要推手是中央政府.     

Emerging Securities Exchanges in Africa

ABSTRACT

African securities markets have not received the academic attention of those in Latin America and Southeast Asia. Historically, capital markets have not played a significant role in financing the development of the African economy. Today, however, African governments are focusing on the importance of moving toward more market-oriented economies and developing the financial market infrastructure to mobilize funds from both the private and public sectors. This paper describes the institutional characteristics of a newly revitalized stock exchange in Nairobi, Kenya. The study concludes that historical and cultural factors play a significant role in the characteristics of the Nairobi Stock Exchange.     

Price assessments by consumers: influence of purchase context and price structure

Among the numerous factors that influence decisions on prices, consumer behaviour has special significance. This paper reviews and analyses relevant studies conducted during the last few decades. On the basis of our analysis, four categories of factors that determine consumer behaviour have been identified. Additionally, we have developed an experimental research design to analyse the influence that the following factors have on price perception: price structure (i.e. price level, order of presentation and price differences), purchase context (i.e. reason for purchase or product use) and demographic characteristics (i.e. gender). Results reveal a significant influence of these variables on consumer behaviour.     

Information Shocks and the Dynamics of the Housing Market*

In this paper, we analyze housing‐market reactions to the release of previously unpublished information on school quality. Using high‐quality housing data, which precisely bracket the timing of the information shock, we investigate housing‐price dynamics within school‐catchment areas. We find a robust short‐term housing‐market reaction to the publication of school‐quality indicators, suggesting that this information was new to the households, and that households are willing to pay for better schools. The publication effect does not seem to be permanent as prices revert to pre‐publication levels after two to three months.     

Voluntary Disclosure and Equity Offerings: Reducing Information Asymmetry or Hyping the Stock?*

We examine corporate disclosure activity around seasoned equity offerings and its relationship to stock prices. Beginning six months before the offering, our sample issuing firms dramatically increase their disclosure activity, particularly for the categories of disclosure over which firms have the most discretion. The increase is significant after controlling for the firm's current and future earnings performance and tends to be largest for firms with selling shareholders participating in the offering. However, there is no change in the frequency of forward‐looking statements prior to the equity offering, something that is expressly discouraged by the securities law. Firms that maintain a consistent level of disclosure experience price increases prior to the offering, and only minor price declines at the offering announcement relative to the control firms, suggesting that disclosure may have reduced the information asymmetry inherent in the offering. Firms that substantially increase their disclosure activity in the six months before the offering also experience price increases prior to the offering relative to the control firms, but suffer much larger price declines at the announcement of their intent to issue equity, suggesting that the disclosure increase may have been used to “hype the stock” and the market may have partially corrected for the earlier price increase. Firms that maintain a consistent disclosure level have no unusual return behavior relative to the control firms subsequent to the announcement, while the firms that “hyped” their stock continue to suffer negative returns, providing further evidence that the increased disclosure activity may have been hype, and suggesting that the hype may have been successful in lowering the firms' cost of equity capital.     

A methodology for the choice of the best fitting continuous-time stochastic models of crude oil price

The crude oil price is generally considered as the fundamental factor in the valuation of undeveloped reserves but it is not the unique one. Undeveloped field value also depends on the uncertainty relating to the convenience yield and the risk-free interest rate. The purpose of this paper is to decide on the best continuous-time stochastic models for these risk factors. The Generalized Method of Moments and the Maximum Likelihood Estimation are implemented to fit the parameters of continuous-time stochastic processes. The results of unit root tests without breaks reveal a mean reversion in convenience yield series. Multiple structural change tests show that the risk-free interest rate can be considered constant. The simulation of continuous-time stochastic processes and the mean error between the simulated prices and the market ones show that the Geometric Brownian Motion with jumps is the best model for the oil price compared to the other commonly used processes.     

The Welfare Economics of a Biofuel Tax Credit and the Interaction Effects with Price Contingent Farm Subsidies

A framework is developed to analyze the effects of a biofuel consumer tax exemption and the interaction effects with a price contingent farm subsidy. Ethanol prices rise above the gasoline price by the amount of the tax credit. Corn farmers gain directly while gasoline consumers only gain from any reduction in world oil prices due to the extra ethanol production. Domestic oil producers lose. Historically, the intercept of the ethanol supply curve is above the gasoline price. Hence, part of the tax credit is redundant and represents "rectangular" deadweight costs that dwarf triangular deadweight cost measures of traditional farm subsidies.     

The stock market and investment in the small and open Norwegian economy

The relationship between the stock market and investment is analyzed by utilizing a multivariate vector autoregressive model, which also includes fundamentals represented by production and the bank interest rate. Two important results appear on the basis of data from the small, open economy of Norway. The financial market has no lead effect on real activity, as neither the stock market nor the credit market can predict future investment or production. On the contrary, current stock returns correlate negatively with lagged growth in investment, and positively with current growth in production. In addition, changes in the bank interest rate have a positive effect on future stock returns, production leads investment positively, and both production and the bank interest rate become exogenous variables in our model. First version received: November 1997/Final version received: October 2000