价格歧视战略与福利效应分析

在完全竞争市场条件下 ,竞争均衡可实现帕累托最优效率。垄断市场一般很难提供价格等于边际成本的产量水平 ,其产量与价格选择对社会来说不是最优的。垄断厂商以内生范畴和外生范畴为基础对消费者进行分类 ,使得价格歧视成为一种可行战略。由于定价策略存在差异 ,不同类型的价格歧视便具有不同的福利效应。     

Modelling the dynamics of Bitcoin and Litecoin: GARCH versus stochastic volatility models

We examine and compare a large number of generalized autoregressive conditional heteroskedastic (GARCH) and stochastic volatility (SV) models using series of Bitcoin and Litecoin price returns to assess the model fit for dynamics of these cryptocurrency price returns series. The various models examined include the standard GARCH(1,1) and SV with an AR(1) log-volatility process, as well as more flexible models with jumps, volatility in mean, leverage effects, t-distributed and moving average innovations. We report that the best model for Bitcoin is SV-t while it is GARCH-t for Litecoin. Overall, the t-class of models performs better than other classes for both cryptocurrencies. For Bitcoin, the SV models consistently outperform the GARCH models and the same holds true for Litecoin in most cases. Finally, the comparison of GARCH models with GARCH-GJR models reveals that the leverage effect is not significant for cryptocurrencies, suggesting that these do not behave like stock prices.     

Nonparametric estimation of stochastic volatility models

This letter introduces nonparametric estimators of the drift and diffusion coefficient of stochastic volatility models which exploit techniques for estimating integrated volatility with high-frequency data. The performance of the proposed estimators is assessed on simulations of two popular stochastic volatility models.     

价格涨跌幅限制起到了助涨助跌作用吗?

价格涨跌幅限制是否具有助涨助跌作用对于判断涨跌幅限制的实施效果具有重要的意义。既有的研究表明 ,股价在发生涨跌停时存在一定的过度反应。然而 ,本研究发现 ,在股价发生涨跌停时 ,虽然涨跌幅限制不能完全消除过度反应 ,但是可以显著地减小而不是增大过度反应的程度。本研究还发现 ,价格涨跌停本身并不是导致过度反应的原因 ,因为股价不仅在涨跌停时存在过度反应 ,而且在大幅度变化但未达到涨跌停时也存在过度反应。本文据此认为 ,没有证据表明价格涨跌幅限制具有助涨助跌作用。     

证券交易机制影响股价吗?——对中国股票市场的再检验

本文在对分别按照开盘价和收盘价计算的两种收益率的比较中发现了极值聚集现象 ,文中将形成这一现象的原因归结于市场中涨跌幅限制的存在 ,并建立了一个简单模型对此进行了说明。其后 ,利用市场中不存在涨跌幅限制时期的数据对该模型进行了验证。在结论部分 ,本文分析了除交易机制外造成两种收益率差异的其他因素 ,并认为有关交易机制对股价行为影响的研究有待深入。     

Valuation of commodity derivatives in a new multi-factor model

This paper extends existing commodity valuation models to allow for stochastic volatility and simultaneous jumps in the spot price and spot volatility. Closed-form valuation formulas for forwards, futures, futures options, geometric Asian options and commodity-linked bonds are obtained using the Heston (1993) and Bakshi and Madan (2000) methodology. Stochastic volatility and jumps do not affect the futures price at a given point in time. However, numerical examples indicate that they play important roles in pricing options on futures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Implied Volatility of Interest Rate Options: An Empirical Investigation of the Market Model

We analyze the empirical properties of the volatilityimplied in options on the 13-week US Treasury bill rate. These options havenot been studied previously. It is shown that a European style put optionon the interest rate is equivalent to a call option on a zero-coupon bond.We apply the LIBOR market model and conduct a battery of validity tests tocompare three different volatility specifications: contact, affine, and exponentialvolatility. It appears that the additional parameter in the affine and theexponential volatility function is not justified. Overall, the LIBOR marketmodel fares well in describing these options.     

Estimating daily volatility in financial markets utilizing intraday data

This study proposes a new approach to the estimation of daily realised volatility in financial markets from intraday data. Initially, an examination of intraday returns on S&P 500 Index Futures reveals that returns can be characterised by heteroscedasticity and time-varying autocorrelation. After reviewing a number of daily realised volatility estimators cited in the literature, it is concluded that these estimators are based upon a number of restrictive assumptions in regard to the data generating process for intraday returns. We use a weak set of assumptions about the data generating process for intraday returns, including transaction returns, given in den Haan and Levin [den Haan, W.J., Levin, A., 1996. Inferences from parametric and non-parametric covariance matrix estimation procedures, Working paper, NBER, 195.], which allows for heteroscedasticity and time-varying autocorrelation in intraday returns. These assumptions allow the VARHAC estimator to be employed in the estimation of daily realised volatility. An empirical analysis of the VARHAC daily volatility estimator employing intraday transaction returns concludes that this estimator performs well in comparison to other estimators cited in the literature.     

Contagion Effects from the 1994 Mexican Peso Crisis: Evidence from Chilean Stocks

The contagion, or informational spillover, effects of the 1994 peso crisis from the Mexican market to the Chilean market, and to the Chilean American Depository Receipts (ADRs) trading in the U.S., are examined. Significant excess returns are observed for Chilean stocks for the event dates of the Mexican Peso crisis, providing evidence of contagion effects. Significant excess returns on these Chilean ADRs are also observed for each of the five event dates associated with the Peso crisis, suggesting that the contagion effects spilled over to the ADRs. A multiple regression model shows that the spillover contagion effects were very efficiently transmitted from the Mexican market to the Chilean market to the Chilean ADRs. Multifactor regressions show that the most significant influence on the pricing of Chilean ADRs is the raw Chilean Index, rather than the Chilean Index expressed in U.S. dollars.     

A Closer Look at the Relation between GARCH and Stochastic Autoregressive Volatility

We show that, for three common SARV models, fitting a minimummean square linear filter is equivalent to fitting a GARCH model.This suggests that GARCH models may be useful for filtering,forecasting, and parameter estimation in stochastic volatilitysettings. To investigate, we use simulations to evaluate howthe three SARV models and their associated GARCH filters performunder controlled conditions and then we use daily currency andequity index returns to evaluate how the models perform in arisk management application. Although the GARCH models produceless precise forecasts than the SARV models in the simulations,it is not clear that the performance differences are large enoughto be economically meaningful. Consistent with this view, wefind that the GARCH and SARV models perform comparably in testsof conditional value-at-risk estimates using the actual data.