股指成份股调整与股价崩盘风险:基于一项准自然实验的证据

本文考察了入选沪深300指数成份股对该公司未来股价崩盘风险的影响。为缓解内生性问题,本文利用中国特有的备选股制度所提供的准自然实验机会,以备选股作为对照组,采用双重差分模型进行了实证检验。分析结果表明,相比备选股,公司在入选成为股指成份股之后,其股价崩盘风险显著上升。进一步的路径检验发现,分析师乐观预测偏差及分析师跟随在其间起到了部分中介效应。本研究不但有助于更好地理解股价崩盘风险动因和股指成份股调整的经济后果,也为监管部门加强分析师监管、完善成份股调整制度提供了决策参考。     

The price discovery role of day traders in futures market: Evidence from different types of day traders

Using proprietary account-level transaction data in the futures market where day traders are self-declared ex ante, this study investigates whether day traders enhance price discovery at the market level. From a natural classification of day traders, we find that heterogeneous day traders have differential effects on price discovery. Self-declared day traders, who benefit from low margin requirement, do not improve price discovery measured by information share. In contrast, non-declared traders, who are not self-declared as day traders, improve price discovery. Their positive impacts on price discovery are particularly significant during periods of high volatility and arrival of new information. Overall, a margin stimulating policy may encourage more day trading, but may also attract overconfident investors, especially inexperienced ones, and who do not enhance price discovery.     

Short-term overreaction to specific events: Evidence from an emerging market

This paper investigates the short-term overreaction to specific events and whether stock prices are predictable in the Egyptian stock exchange (EGX). We find evidence of the short-term overreaction in the EGX. Losers (“bad news” portfolios) significantly outperform winners (“good news” portfolios) and investors can earn abnormal return by selling the winners and buying losers. Terrorist attacks have negative and significant abnormal returns for three days post event followed by price reversals on day four post event. Whereas, the tensions in the Middle East region have a negative and significant abnormal returns on event day followed by price reversals on day one post event. Moreover, the formation of a new government has no effect on the average abnormal returns post event in the EGX. The results also show that small firms tend to have greater price reversals compared to large firms. Overall, our results provide evidence of the leakage of information in the EGX.     

凤尾变鸡头:被忽视的指数成分股交换

沪深300和中证500同时调整成分股,沪深300调出的股票大部分会进入中证500。这些交换的成分股既有沪深300调出效应,也有中证500调入效应。已有文献专注于沪深300调出样本整体的调出效应,却忽视了交换股还有中证500调入效应。本文首先使用断点回归设计研究交换股,证明了指数效应在国内存在。随后,使用Fama-French五因子模型研究交换股与其它沪深300调出股的差异,解释了为何国内研究认为指数效应不存在:交换股主要表现出调入效应,抵消了其它沪深300调出股的调出效应,忽视指数成分股交换导致了整体调出效应"不显著",甚至为正。     

股指期权对股指期货的促进作用:来自韩国的证据

本文结合解析韩国KOSPI200期权对于KOSPI200期货市场的影响,论证股指期权市场对股指期货市场在提高流动性和培育机构投资者方面的显著作用。借鉴韩国股指衍生品市场发展经验,笔者认为在沪深300股指期货平稳运行之后,要选择时机及时推出股指期权,这样可以保证良好的流动性。为此,应当加快制定股指衍生品市场体系的发展战略。     

投资者异质性与证券市场定价——理论模型与中国的经验证据

本文从投资者异质性的客观现实出发,通过对投资者二维视角的交叉分类与相关行为的探讨,提出了一种按交易特点与行为依据的新的分类方案,即将投资者分为套利交易者、价格预期交易者和量能变动交易者三类。在此基础上分别建立了各类投资者的需求函数,通过对证券市场供求函数的讨论,利用均衡分析方法构建了基于投资者异质性的证券市场定价模型,并以我国证券市场1999-2011年的月度数据为样本进行了实证分析。实证结果表明:我国证券市场价格主要由价格预期交易者的诱导性策略行为与量能变动交易者的羊群行为决定,套利交易者的套利行为对市场价格没有显著的影响,证券市场扩容也未对市场价格的形成产生系统性冲击。     

Aggressive reporting,investor protection and stock price informativeness: Evidence from Chinese firms

This paper investigates the impact of aggressive reporting on the ability of stock prices to inform in Chinese firms. Using both stock price synchronicity and the probability of informed trading as proxies for stock price informativeness, we find that aggressive reporting damages the ability of stock prices to inform in Chinese firms. Our findings are robust to potential endogeneity and the use of alternative aggressive-reporting measures. Finally, we find that the impact of aggressive reporting in reducing stock price informativeness is stronger in firms located in regions of weaker institutional development and in private sectors firms.     

A re-examination of the index effect: Gambling on additions to and deletions from the S&P 500's ‘gold seal’

This study examines the abnormal returns, trading activity, volatility and long-term performance of stocks that were added to the S&P 500 index. By using a three-factor pricing model that allows for firm size and value characteristics as well as market risk, we are able to shed new light on the widely observed ‘index effect’. We find that the CAPM tends to overstate the performance of large firms and to understate the performance of small firms. We also find a transitory increase in trading volume between the announcement and a few days after the effective date. In terms of the firm's operating performance, we find a significant increase in earnings per share after inclusion, which combines with the stock price rise to leave the average price-earnings ratio largely unaltered. Examining a unique sample of deletions of international companies and replacements with US companies, we find that deleted stocks experienced a considerable and permanent fall in price, inconsistent with the Investor Recognition Hypothesis. The “seal” of S&P 500 index membership has very long-term effects and inclusion appears not to be an information-free event.     

The ex-dividend day stock price anomaly: evidence from the Greek stock market

This paper examines the ex-dividend stock price and trading volume behavior in the Greek stock market for the period 2000–2004. We use both standard event-study methodology and cross-sectional regression analysis in assessing the ex-dividend stock price anomaly. We find that stock prices drop less than the dividend amount. By examining abnormal returns as well as abnormal trading volume around the ex-dividend day, we find strong evidence of short-term trading, which is consistent with the presence of dividend-capturing activities around the ex-dividend day. The results from the cross-sectional regression analysis confirm that the short-term trading hypothesis explains the ex-dividend day stock price anomaly in Greece.

Short sales, price pressure, and the stock price response to convertible bond calls

The announcement of a convertible bond call is associated with an average contemporaneous abnormal stock price decline of 1.75% and an ensuing price recovery in the conversion period. A price fall and the subsequent recovery suggest price pressure as the explanation for the announcement effect. However, in general the option to convert is not exercised early and hence, the increase in the number of shares outstanding does not occur at the announcement date. Instead, this paper argues and provides evidence that hedging-induced short selling causes at least part of the short-run price pressure.     

投资者分歧、异常交易量和股票横截面收益率预测——基于中国股票市场的经验证据

本文定义月度异常交易量为本月与上个月交易金额的比值,发现中国市场月度收益率与滞后一个月的异常交易量显著负相关。在控制了公司规模、账面市值比、流动性以及动量效应等指标后仍然具有显著的解释作用。进一步研究表明,在出现高异常交易量后的12个月内,换手率和特质性波动率都有大幅上升。本文认为,交易量上升代表着市场分歧程度和受关注程度的增加,在卖空约束下会使得股票价值高估,从而造成未来收益率下降。     

The determinants of price discovery: Evidence from US-Canadian cross-listed shares

We examine the determinants of price discovery for Canadian firms cross-listed on the main US stock exchanges over the period 1996–2011. Sampling at a one-minute frequency, we compute Gonzalo and Granger Component Shares (CS) and employ a system GMM approach to control for persistence in price discovery and endogeneity between CS and its determinants. We find that price discovery is highly persistent and that there is strong evidence of simultaneity between CS and its determinants. We conclude that lower relative spreads and higher relative trading activity increase an exchange’s contribution to price discovery. We also document that it is small trades that drive price discovery, particularly since the introduction of decimalization.     

Stock Price Behavior over Trading and Non-trading Periods: Evidence from the Taiwan Stock Exchange

This paper examines the stock price behavior in the trading and non-trading periods for stocks listed on the Taiwan Stock Exchange over 1971-96. The results indicate that the trading-time return variances are higher than the non-trading-time return variances especially for the larger trading-volume quintiles. This result is consistent with the private information hypothesis. Moreover, open-to-open return variances are higher than close-to-close return variances. Since both the opening and the closing transactions are conducted by the call auction procedure, the results are consistent with the trading halt hypothesis but not with the trading mechanism hypothesis.     

Differently motivated exchange traded fund trading activities and the volatility of the underlying index

This paper examines the correlations between two types of a market index's volatility and three trading motives of the index's exchange traded funds (ETFs). We find that ETF trading driven by belief dispersion is highly correlated with both the variance in efficient price innovations (VEPI) and the index's total volatility. Privately informed ETF trading is closely connected to the VEPI but not the total volatility, while liquidity ETF trading explains the total volatility but has little power in explaining the VEPI. Moreover, the leading ETF dominates smaller ETFs in explaining both types of volatility and often has more explanatory power than control variables.     

Feedback trading in stock index futures: Evidence from South Africa

This study tests whether investors and speculators in stock index futures contracts on the South African stock market use feedback trading strategies. Feedback trading can be destabilizing and impede on the risk mitigation and price discovery functions of futures contracts. Using the Sentana and Wadhwani (1992) model, and accounting for the global financial crisis, we find no evidence of feedback trading in the Top40 futures index or the Top40 mini futures index contracts. Our findings have important implications for investors who wish to use index futures to mitigate risk or exploit arbitrage opportunities and regulators concerned about the destabilizing effects of futures trading.     

On the long-term or short-term dependence in stock prices: Evidence from international stock markets

This study examines the short- and long-term dependence in the United States and 21 international equity market indexes. Two heteroscedastic-robust testing methods, the modified rescaled range analysis and the rescaled variance ratio test, are employed to test for the existence of dependence. The evidence consistently reveals the absence of long-term dependence in these 22 stock returns indexes. The random walk hypothesis for most, but not all, stock returns indexes is not rejected. When the random walk hypothesis is rejected, the evidence supporting the rejection is weak and the stochastic dependence occurs mainly in short-horizon, rather then long-horizon holding period returns.     

沪深300指数期货价格随机利率效应研究

经典持有成本模型在非随机利率假设无法满足的条件下仅仅是远期合约而非期货的定价模型。本文采用拟合SHIBOR曲线的方法生成无风险纯折现债券模拟价格序列,对沪深300指数期货价格的随机利率效应进行了实证检验。研究结果表明,由于利率管制、股指期货市场和货币市场发展不成熟等因素的共同作用,沪深300指数期货价格中不含随机利率效应,指数远期和期货理论价格相等;如果持有成本模型其他假设条件也得到满足,则该模型可以用于沪深300指数期货定价。     

The liquidity cost implications arising from the attraction of regional primary listings: Evidence from West Africa

This study reviews the liquidity costs for firms in outlying regions in primary listing on a centralized stock exchange. Using a unique hand-collected sample comprising all listed firms from across West Africa we find evidence that firms from outlying regions do have higher illiquidity costs although these can be mitigated from improvements in transparency that are associated with increasing familiarity amongst investment community of central exchange. This evidence has implications regarding the integration of stock exchanges in developing regions where this is likely to result in a greater concentration of liquidity mitigating intended optimal redistribution of capital and resources.