STOCK RETURNS AND VOLATILITY ON CHINA'S STOCK MARKETS

We examine time‐series features of stock returns and volatility, as well as the relation between return and volatility in four of China's stock exchanges. Variance ratio tests reject the hypothesis that stock returns follow a random walk. We find evidence of long memory of returns. Application of GARCH and EGARCH models provides strong evidence of time‐varying volatility and shows volatility is highly persistent and predictable. The results of GARCH‐M do not show any relation between expected returns and expected risk. Daily trading volume used as a proxy for information arrival time has no significant explanatory power for the conditional volatility of daily returns. JEL classification: G15     

STOCK RETURNS AND OPTION PRICES: AN EXPLORATORY STUDY

This study is an investigation of estimates of expected stock returns implicit in option data. The Lee-Rao-Auchmuty option valuation model provides a unique opportunity to examine whether return measurements derived by nonlinear estimation techniques show any correlation with future stock returns. During the short period covered in this study, the Lee-Rao-Auchmuty estimates give preliminary indications that they are better predictors of actual stock returns than are estimates obtained from historical data.     

ANALYZING STOCK MARKET VOLATILITY USING EXTREME‐DAY MEASURES

We develop a simple measure of volatility based on extreme‐day returns and apply it to market returns from 1885 to 2002. Because returns are not normally distributed, the extreme‐day measure, which is distribution free, might provide a better measure of stock market risk than the traditional standard deviation. The extreme‐day measure more accurately explains investor behavior relative to standard deviation as shown by equity fund flows, and we find evidence that large negative changes appear to influence investor behavior more than large positive changes.     

ON THE RATIONALITY OF COMMON STOCK RETURN VOLATILITY

This paper derives the relationship between the population unconditional variance of common stock returns and the variance of expected returns conditional on a well-specified information set. As a consequence, a lower bound is obtained for the variance of common stock returns. The sample counterpart of this bound is then empirically tested against the sample variance of returns. The paper's main conclusion can be stated as follows: the observed volatility of real (inflation-adjusted) common stock returns is not “irrationally” large. The paper admits of this conclusion because the point estimate of the lower-bound variance derived in this model is actually larger than the point estimate of common stock return volatility. However, since these point estimates are found to have a statistically insignificant difference, equality of the two variances cannot be ruled out. Hence, “rationality” of common stock returns—as implied by a utility-based valuation conditional on a specified information set—cannot be rejected.     

THE EFFECTS OF THE ANNOUNCEMENTS OF DIVIDEND INCREASES ON STOCK RETURN VOLATILITY: THE EVIDENCE FROM THE OPTIONS MARKET

This paper examines the impact of the announcements of dividend increases on the volatility of underlying stock returns implied by option prices, and analyses whether the impact is related to the label associated with the dividend increase. The results suggest that the announcements of labelled dividend increases are accompanied by a decrease in implied volatility, while the announcements of unlabelled increases in dividends are associated with no change in implied volatility. These results are consistent with the hypothesis that signal implicit in the announcements of dividend increases provides noisy information about the firm's volatility.     

市场有效理论及我国股票市场有效性的实证检验

我国股票市场近年来出现的一系列事件引发了人们的深刻思考,而传统的资本市场理论已无法圆满地解释我国股票市场现有的发展程度、发展阶段及有效性等问题.为此,本文提出了市场有效性理论.利用该理论,作者通过抽样统计,对我国股票市场的有效性进行了实证分析.本文的重点在于研究我国股票市场的发展层次即其有效性层次.首先通过随机游程和股价自回归检验方法得出了我国股票市场处于弱型有效的结论,然后针对目前关于有效性层次方面的争论,用事件研究法阐述了如下观点:我国股票市场目前正处于弱型有效市场层次,但并不具有半强型有效市场的特点.     

AN EMPIRICAL TEST OF AN EX-ANTE MODEL OF THE DETERMINATION OF STOCK RETURN VOLATILITY

The assumption that changing expected cash flows and discount factors affect a security's return is at the foundation of many financial models. This study examines empirically the hypothesis that expected stock return variability is a function of cash flow and discount rate uncertainty. Maximum likelihood estimation techniques and expectational data are employed. Strong, positive relationships are found, verifying the foundations of the ex-ante models with ex-ante data and providing a better understanding of security markets by explaining, in part, the causes of expected stock price variability.     

CHANGING VOLATILITY AND THE PRICING OF OPTIONS ON STOCK INDEX FUTURES

This paper presents empirical results regarding the suitability of the Black model for the pricing of options on stock index futures. Whaley's technique is used to present empirical evidence regarding the pricing biases of the model. Information provided by the implied volatilities suggests that model refinements should address the changing volatility issue.     

FOREIGN-CURRENCY OPTIONS, EX ANTE EXCHANGE-RATE VOLATILITY, AND MARKET EFFICIENCY: AN EMPIRICAL TEST

“The currency option's attraction results from the volatility of foreign-exchange markets, where rates can move as much as 3 percent in a day” (M. Sesit, Wall Street Journal, April 20, 1984, p. 25). This study compares the foreign-exchange rate implicit volatility of call options and put options that are written on a foreign currency. These implicit volatilities should be equal, and equal to the volatility of the proportional change in the exchange rate, given that option prices are efficient and that the foreign-currency option pricing model described by Biger and Hull holds. The foreign-currency options that are examined in this study are the British pound, Canadian dollar, Japanese yen, Swiss franc, and West German mark. The results of this study support the notions of market efficiency and put-call parity.     

STOCK MARKET SEASONALITY AND TAXES: AN EXAMINATION OF THE TAX-LOSS SELLING HYPOTHESIS

Recent empirical studies have found evidence that supports the tax loss selling explanation of seasonal effects in stock returns. Using other test procedures, the present authors conclude that the support found in other studies is likely to be the result of spurious correlation between returns of stocks selected as tax-loss selling candidates and the January returns of these stocks.