中国股市存在"特质波动率之谜"吗?

文章讨论了中国股市是否存在特质波动率之谜,实证结果表明,滞后的特质波动率并不是预期特质波动率的一个好的估计值。所谓特质波动率之谜是由于研究者错误地使用滞后的特质波动率来取代预期特质波动率而出现的伪现象。文章采用对每支股票的对数特质波动率序列建立ARMA模型的方法提取预期特质波动率,并利用横截面回归研究预期特质波动率与预期收益率之间的关系,研究结果表明两者之间存在显著的正向关系,这种正向关系即使在考虑了各种控制变量并经过稳健性检验之后仍然成立。     

基于异质信念的公司特质风险定价模型

文章讨论了加入异质信念后公司特质风险对预期收益率的影响。通过放宽经典Merton模型的假设条件,加入异质信念和卖空限制,重新推导了特质波动率与预期收益率之间的关系。结果表明,在投资者无法多样化投资的前提下,即使考虑了异质信念,公司特质波动率仍然进入资产定价方程,特质波动率与预期收益率之间存在正向关系。     

Does High Service Quality Reduce Risk or Create Idiosyncratic Returns?

This article explores the impact of service quality on idiosyncratic returns, idiosyncratic risk (nonsystematic risk), and beta (systematic risk). Service quality was derived from the airline quality rating, and three dependent variables were calculated by the Fama–French four-factor model. The data includes 1,512 monthly records from 1997 to 2006, across 21 airlines. Multiple regression and vector autoregressive models were applied to test relationships among all, low-cost, and non-low-cost airlines. The study found that service quality has a positive impact on idiosyncratic returns in non-low-cost airlines; non-low-cost airlines are less affected by changes in the external environment.     

The impact of crisis events on the stock returns volatility of international airlines

This paper adopts the generalized autoregressive conditional heteroskedasticity model to examine the relationship between the weekly returns of shares of the international airlines in 1996–2010. It also incorporates major international crisis events and observes the influence of different aspects on the volatility of returns of company shares. Different events exhibit significantly different regional volatility impulses in the countries in which the airlines are located. The Asian financial crisis enhances the returns volatility effects of Asian airline companies. The global financial crisis significantly intervenes with the returns volatility of airline companies around the world. The results suggest that major international events may all have risk effects on the returns on the share prices of airlines.     

Mergers and Acquisitions and Market Volatility of Brazilian Banking Stocks: An Application of GARCH Models

The main objective of this research was to investigate the impacts caused by announcements of mergers and acquisitions (M&As) on the volatility of the returns of Brazilian bank stocks from 1994 to 2015. In order to achieve the proposed objective, this study applied Generalized Autoregressive Conditional Heteroscedastic (GARCH) class models to the series to model their volatility. Our results confirmed the impact of the announcement of M&As on volatility. They suggest that M&A announcements are expected to cause a negative reaction if related to an expansion or a deal involving a less-well known bank, and a positive reaction if it involves well-known bank with good reputation—a higher level of confidence and a lower level of information asymmetry for investors.     

Economic uncertainty,trading activity,and commodity futures volatility

This paper investigates the dynamics of commodity futures volatility. I derive the variance decomposition for the futures basis and show unexpected excess returns result from new information about expected future interest rates, convenience yields, and risk premia. Measures of uncertainty in economic conditions have significant predictive power for realized volatility of commodity futures returns, after controlling for lagged volatility, returns, commodity index trading, hedging pressure, and other trading activity, even during the so-called “index financialization” period. During this period, hedge fund performance predicts volatility in grain commodities, which are affected by the US ethanol mandate.     

Impact of international energy prices on China's industries

This study examines how returns and volatility of future contracts for Brent crude oil (Brent), West Texas Intermediate crude oil (WTI), Henry Hub natural gas, and Newcastle thermal coal impacts industries in China. Using the firm-level data of 3,750 stock listings across both Shanghai and Shenzhen stock exchanges, segregated into 138 subindustries under the Global Industry Classification Standard, this study finds evidence that crude oil futures have the most significant influence. Further analysis suggests that stock returns of oil-related companies are more closely align to Brent and WTI's futures returns following China's key oil pricing reform on March 27, 2013. Overall, Chinese industries are also more exposed to global crude oil futures volatility after this event.     

The information content in implied idiosyncratic volatility and the cross‐section of stock returns: Evidence from the option markets

Current literature is inconclusive as to whether idiosyncratic risk influences future stock returns and the direction of the impact. Earlier studies are based on historical realized volatility. Implied volatilities from option prices represent the market's assessment of future risk and are likely a superior measure to historical realized volatility. Implied idiosyncratic volatilities on firms with traded options are used to examine the relationship between idiosyncratic volatility and future returns. A strong positive link was found between implied idiosyncratic risk and future returns. After considering the impact of implied idiosyncratic volatility, historical realized idiosyncratic volatility is unimportant. This performance is strongly tied to small size and high book‐to‐market equity firms. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28: 1013–1039, 2008     

Speculation and volatility—A time-varying approach applied on Chinese commodity futures markets

Experts have long discussed and empirically investigated whether speculative activity increases volatility on commodity futures markets. Little empirical research, however, analyzes the role of speculators on commodity futures markets in China. Using time-varying vector autoregression models with stochastic volatility, this paper investigates for four heavily traded metal and agricultural contracts, how the relationship between returns volatility and speculation evolves over time. Our findings indicate that speculative activity has little to no impact on volatility. On the contrary, for all commodities examined, returns volatility seems to amplify speculation.     

中国开放式基金收益及其波动性的周内效应研究

了解基金收益及其波动性是否存在周内效应对投资者非常重要,投资者可以利用收益及其波动性的变动信息调整投资组合,增加投资收益。运用均值方程含有虚拟变量的GARCH(1,1)模型和条件方差方程含有虚拟变量的修正的GARCH(1,1)模型,我们分别对2003年6月1日至2005年8月18日期间中国开放式基金收益的周内效应和收益波动性的周内效应进行实证研究,结果显示,在研究期间内样本基金收益及收益的波动性在周三这一天显著不同于其他交易日,即存在“周三效应”。     

Evidence on the dynamic relationship between international trade and the stock market

This study uses vector autoregressive analysis to examine the dynamic interactions of monthly real stock returns, return volatility, exchange rates, export growth and import growth for Hong Kong, Korea, Singapore, and Taiwan for the period 1975–91. We find that exports and imports have significant interactions. The results also indicate that stock returns in Hong Kong and Singapore Granger-cause trade flows. Return volatility is found to react strongly to trade news in all four countries, a result supporting the efficient-market hypothesis.     

我国股票市场收益、交易量、波动性动态关系的实证分析

本文对我国股票市场上证指数和深圳成指的收益、交易量、波动性之间的动态关系进行了实证研究,研究结果表明:收益和绝对收益与交易量之间均存在正相关关系;收益与交易量以及绝对收益与交易量之间存在双向Granger因果关系(线性或非线性);深圳成指收益的波动方差对收益具有正向作用,而上证指数收益的波动方差对收益没有直接的影响;上证指数和深圳成指的成交量对股指收益的波动方差不具有解释作用.     

The effect of spot and futures trading on stock index market volatility: A nonparametric approach

This article provides empirical evidence on the intraday relation between spot volatility and trading volume in the Spanish stock index futures market. GARCH methodology is used to estimate spot volatility. We analyze the potential relation between spot and futures trading volume and spot volatility by estimating the corresponding conditional density functions as proposed in Quah (1997). Our results reveal no significant link between those variables. Similar findings arise when expected and unexpected volume is considered. Our results suggest that derivative market is not a force behind episodes of significant spot jump volatility. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:841–858, 2003     

Market volatility and the demand for hedging in stock index futures

This study examines the relation between stock market volatility and the demand for hedging in S&P 500 stock index futures contracts. Open interest is used as a proxy for hedging demand. The analysis employs unique data that identify separately the open interest of large hedgers, large speculators, and smaller traders. Volatility estimates are decomposed into expected and unexpected components, to assess whether traders’ reactions to volatility depend upon its predictability. Results indicate that daily open interest for hedgers increases when unexpected volatility increases. Increases in unexpected volatility may cause hedgers to raise their estimates of future expected volatility, and hence increase their demand for hedging. Open interest of speculators is not related to expected volatility, and is only weakly related to unexpected volatility. The increase in the participation of hedgers in periods of higher volatility is significantly larger than the increase in the participation of speculators. The results suggest that increases in stock market volatility increase the demand for hedging. © 2000 John Wiley & Sons, Inc. Jrl Fut Mark 20: 105–125, 2000     

Show me the money: Option moneyness concentration and future stock returns

Informed traders often use options that are not in-the-money due to higher potential gains for a smaller upfront cost. Thus, trading activity by option moneyness should be a gauge of informed option trading. We construct a dollar volume-weighted average moneyness measure to capture option trading activity at different moneyness levels. Stock returns increase with this measure, suggesting more trading activity in options with higher leverage predicts future stock returns. Our results hold cross-sectionally and at the portfolio level yielding a Fama–French five-factor α of 12% per year for all stocks and 33% per year for high implied volatility stocks.     

The implied volatility smirk of commodity options

This paper studies the implied volatility (IV) smirks in four commodity markets by adopting Zhang and Xiang's methodology. First, we document the term structure and dynamics of IV smirks. Overall, the commodity IV curves are negatively skewed with a positive curvature. Then we analyze the commodity and S&P 500 returns' predictability based on in‐sample and out‐of‐sample tests and find that the information embedded in IV smirks can significantly predict monthly commodity and S&P 500 returns. For example, the risk‐neutral fourth cumulant (FC) from the crude oil market outperforms all of the standard predictors in predicting the S&P 500 returns.     

Corporate Hedging and the High Idiosyncratic Volatility Low Return Puzzle

The literature offers various explanations to either support or refute the Ang et al. ( 2006 ) high idiosyncratic volatility low return puzzle. Fu ( 2009 ) finds a significantly positive contemporaneous relation between return and exponential generalized autoregressive conditional heteroskedastic idiosyncratic volatility. We use corporate hedging to shed light on this puzzle. Conceptually, idiosyncratic volatility matters to investors who face limits to diversification. But limits to diversification become less relevant for firms that consistently hedge. We confirm the main finding in Fu ( 2009 ), but only for firms that do not consistently hedge. For firms that adopt a consistent hedging policy, idiosyncratic volatility, whether contemporaneous or lagged, is insignificant in Fama–MacBeth regressions, controlling for size, book‐to‐market, momentum, liquidity, and industry effects.     

Improving momentum strategies using residual returns and option-implied information

This paper provides an alternative method for enhancing momentum profits by combining residual returns and option-implied information. The results show that the main benefit of applying residual returns to construct momentum portfolios is generating stable returns. Additionally, the incorporation of implied volatility (IV) spread or IV skew into a residual momentum portfolio is found to significantly raise profits, particularly during bad times and high-sentiment periods. This is because IV spread and IV skew can dissociate winners/losers with a price underreaction from those with a price overreaction, which suggests that informed traders who perceive price underreactions/overreactions trade in option markets.     

A smiling bear in the equity options market and the cross-section of stock returns

We propose a measure for the convexity of an option-implied volatility curve, IV convexity, as a forward-looking measure of risk-neutral tail-risk contribution to the perceived variance of underlying equity returns. Using equity options data for individual US-listed stocks during 2000–2013, we find that the average realized return differential between the lowest and highest IV convexity quintile portfolios exceeds 1% per month, which is both economically and statistically significant on a risk-adjusted basis. Our empirical findings indicate the contribution of informed options trading to price discovery in terms of the realization of tail-risk aversion in the stock market.     

Emerging Equity Market Volatility

Abstract

This paper considers two emerging markets that are under-researched, Kenya and Nigeria. It offers a comprehensive view of four time properties that emerged from the empirical time series literature on asset returns: (1) the predictability of returns from past observations; (2) the auto-regressive behavior of conditional volatility; (3) the asymmetric response of conditional volatility to innovations; and (4) the conditional variance risk premium. Results of the exponential GARCH (EGARCH) model indicate that asymmetric volatility found in the U.S. and other developed markets also characterized the Nigerian stock exchange. In Kenya, however, the asymmetric volatility coefficient is significant and positive, suggesting that positive shocks increase volatility more than negative shocks of an equal magnitude. The Nairobi Stock Exchange (KSE) returns series report negative but insignificant risk-premium parameters. In Nigeria (NSE), return series exhibit a significant and positive time-varying risk premium. The results also show that expected returns are predictable, that the auto-regressive return parameters (? ₁ ) are significant in both Kenya and Nigeria. Finally, the GARCH parameter (b) is statistically significant, indicating that volatility persistence is present in the two emerging markets studied.