中国A股市场动量效应和反转效应：实证研究及其理论解释

本文模拟上证180指数交易,通过考察动量和反转策略的收益情况验证中短期动量效应和反转效应的存在性,并分析不同市场形势下的效应差异,之后根据流通市值将A股市场划分为大盘股和小盘股,探讨交易量冲击和收益率冲击下的股价反应不足或过度反应与动量或反转效应之间的关系。论文在BSV模型和HS模型的基础上,对动量和反转效应的形成机制提供一个可能的解释。     

中国股市的惯性与反转效应研究

由于中国股市具有政策市的特征,本文在Hong和Stein(1999)模型的基础上,研究政策市背景下的中国股市的惯性与反转效应。我们的主要结果有:中国股市的反转效应相对于惯性效应要更明显一些,并且除了中期惯性与长期反转外,还存在一个超短期的惯性与短期的反转;同时,小公司股票相对大公司股票,惯性运动的趋势较弱,更容易发生反转,成交量大的股票相对于成交量小的股票,惯性运动的趋势较弱,更容易发生反转。最后通过实证分析,在中国股票市场对上述结果进行了检验,实证结果支持了我们的结论。     

中国股指波动的政策信息和投资者行为效应影响

文章对中国沪深300指数与代表货币政策效应的利率、存款准备金率和代表投资者行为效应的市场成交金额及代表惯性效应的三阶滞后被解释变量进行回归分析,验证了中国股指波动中货币政策信息效应、投资者行为效应以及惯性效应.实证结果发现,存款准备金率对股指波动具有负向作用,成交金额及股指自身的一阶和二阶滞后被解释变量具有显著正向作用,表明货币政策、投资者行为及惯性效应对中国股指波动存在影响.     

证券分析师、内幕消息与资本市场效率-基于中国A股股价中公司特质信息含量的经验证据

本文拓展了RodriguezandSbuelz(2006)模型,引入稳健性偏好来研究中国股市的惯性投资策略和对冲投资策略.稳健性投资者对惯性投资策略反应不足,部分执行反转投资策略,从而印证了实证研究所发现的中国股市在中短期内惯性效应夹杂着反转效应的情况;稳健性投资者对对冲投资策略反应过度,并且随着投资周期的变长,其与一般投资者的对冲投资策略差异拉大;风险规避系数大和存在稳健性偏好的投资者能够把投资策略控制在合理的区间内.     

信息传递模式、投资者心理偏差与股价“同涨同跌”现象

股价"同涨同跌"又称"股价同步性",是世界各国证券市场发展过程中的一种普遍现象,也是近年来财务学的研究热点和前沿课题。本文收集1994—2004年中国股市的相关数据,用R2度量股价同步性,对股票收益的"惯性"和"反转"与R2之间的关系进行系统的实证检验和理论分析。研究发现:(1)总体上,我国股市不存在"惯性"现象,而存在显著"反转"现象,并且反转效应随着R2的上升而逐渐减弱,两者呈负相关关系;(2)不同市场态势下惯性和反转的表现形式不同,且与R2的关系也不同:牛市阶段存在"反转"现象,且R2越高反转越明显;在熊市阶段存在"惯性"现象,且R2越小惯性越明显,说明不同市场态势下股价同步性的生成机理不同。对此,作者提出了一种基于信息与心理行为互动关系的新解释,丰富并完善了股价同步性形成机理的理论研究。     

基于贯性分析市场风险的累积及对投资的启示

本文指出市场除了具有自身调节机制外,市场惯性也在对市场的运行发挥作用.在惯性作用下,市场繁荣时会产生泡沫,复苏过于缓慢,惯性在经济周期中不断累积风险,投资主体应该明确形势,乘惯性而为,在投资策略上灵活运用惯性策略和反转策略.     

市场情绪、溢价与波动

本文在投资者异质性条件下建立了市场情绪与情绪溢价的理论模型,利用封闭式基金折价率、换手率、月度新股首次发行数量、月度新股首次发行收益和基金现金持有比例构建一个衡量市场情绪的综合指标。研究结果表明:中国股市市场情绪产生溢价并使深沪两市的收益产生波动;中国股市不仅有情绪的短期持续性和长期的逆转性,而且存在短期收益惯性和长期收益反转效应;市场情绪是导致中国股市非理性大起大落的重要因素。     

动量与反转效应来源的分解——风格、行业与序列相关性

文章使用Lo和MacKinlay(1990)的相对强度加权策略(WRSS)的研究方法,以A股为研究对象,从风格、行业与序列相关性三方面探讨了动量和反转效应的来源。实证结果显示:个股呈现反转效应,而风格的动量十分明显,行业具有微弱的反转效应。这种不同的主要来源是资产的序列自相关与收益横截面的方差。     

中国股市“惯性策略”和“反转策略”的实证分析

组合投资的两种传统策略是基于收益惯性和收益反转。DeBondtandThaler(1 985)发现较长时期内股票价格运动存在相当程度的收益反转现象 ,而JegadeeshandTit man(1 993)发现较短时期中存在相当程度的收益惯性现象。这些策略的成功可能源于数据挖掘 ,也可能是由于市场因素。为此 ,本文研究了深沪两市 1 993年以前上市的所有股票 ,实证结果显示 ,深沪股票市场存在明显的收益反转现象 ,但没有发现明显的收益惯性现象     

动量和反转投资策略在我国股市中的实证分析

本文采用沪深两市1995年前上市的股票作为样本,发现我国股市中也存在明显的动量和反转盈利,且两种效应的强弱与大盘走势相关,当市场为牛市特征时,动量效应明显强于反转效应;当市场为熊市特征时,则反之.经典的CAPM模型无法解释动量和反转盈利的来源,检验表明投资者对不同类型信息的不同反应方式,可以很好解释我国股市中的动量和反转盈利,利用上述检验结果还可以解释我国股市中许多有趣的特征.     

Momentum in Taiwan: seasonality matters!

Previous studies suggest that momentum exists in international stock markets with the exception of Asia. Using a large data set of Taiwanese stocks, we show that momentum does exist, but it is restricted to the months following the deadline for annual statements. During the remaining months, a reverse momentum, or contrarian, strategy produces significant returns. These contrarian returns are particularly high during the national holidays linked to the Lunar New Year and the Lunar Moon Festival.     

中国股市价值反转投资策略有效性实证研究

本文以中国深沪A股股票市场为考察对象 ,分析了价值反转投资策略的有效性。作者通过实证分析发现 :在中国深沪A股股票市场上 ,以帐面价值与市场价值比 (B M)、B M GS等指标构造的价值反转投资策略可以产生显著的超额收益率 ,并且其显著程度因持有期不同而不同。接着 ,作者利用CAPM模型、Fama French三因素模型并引入了协偏度 (coskewness)和协峰度 (cokurtosis) ,构造出多风险因子模型来解释价值反转投资策略超额收益率。我们发现 :在经过传统风险因素调整后 ,价值反转投资策略效果依然明显 ;CAPM模型无法解释价值反转投资策略超额收益率 ;Fama French三因素模型对价值反转投资策略超额收益率的解释能力最为显著 ,但对于有些价值投资策略 ,在Fama French三因素基础上加上协偏度和协峰度因子后 ,模型的解释能力有所提高     

投资者情绪、异质性与市场非理性反应

许多研究表明,我国证券市场反向策略在短期内获利性较为显著,而动量策略在长期内可以获得超额收益,即中国股市具有短期反应过度和长期反应不足的双重特征。这一现象不仅动摇了有效市场假说的理论基础,而且对现有的行为定价理论模型构成了强有力的挑战。本文尝试从投资者情绪和投资者异质性两个角度对这一异象进行解释。研究发现,在投资者情绪高涨(或低落)阶段,市场更容易反应过度(或反应不足);对于不同类型的投资者,他们的信息反应模式也不尽相同,各自主导了市场在短期内和在长期内的整体表现。这一发现为中国股市在市场非理性反应上所呈现的独有特征提供了很好的阐释。     

股票市场能量体系研究

本文借鉴物理学研究物体运动规律的思想,提出以成交量为基础的标的资产交易速度定义。根据近代物理学相对论质速关系及质能方程的数学模型,提出以价格为基础的标的资产惯性价格以及其动量和能量假说。在此基础上,本文推导出股票市场量能方程,并结合金融市场的动量现象以及动量生命周期假说,构建了股票市场的资产动量和能量体系框架。通过对30只不同股本股票的能量谱进行实证研究,发现当股票能量值大于某一常数时,随后的一段时间里股价将会出现较大的变化,用此能量值可以揭示股票价格是处于稳态还是非稳态。研究30只股票的资产动量与能量之间的数量关系,发现要达到同一能级,大盘股需要较大的动量,而小盘股需要较小的动量。     

The use of trading strategies by fund managers: some first survey evidence

A questionnaire survey has found that most fund managers rely on the strategies of buy-&-hold, momentum and contrarian trading. These strategies are typically applied mutually. Their use is rooted in the attributes and beliefs of the respective fund managers: buy-&-hold traders are fundamentally oriented, risk averse and are less (over)confident than others. Momentum traders appear as the least risk-averse professionals, going aggressively with the trend. Contrarian traders, however, show signs of overconfidence and peculiar risk aversion, both indicating difficulties in successful strategy implementation. The behavioural patterns revealed are not easily reconciled with efficient markets.     

The winner-loser anomaly: recent evidence from Greece

This article finds evidence of significant reversals in returns over the medium term in Greek stocks. In contrast with previous research, return reversals are more pronounced for past winners, suggesting that the market overreacts to a greater extent to good news. These contrarian returns are particularly elevated when portfolios are formed using quartiles and during tranquil and bull markets. The optimum contrarian strategy involves skipping the first 6 months of the holding period and implementing the contrarian strategy for a period of 18 months, as returns exhibit continuation followed by reversal. The profitability of the contrarian investment strategy is robust to adjustments for risk and seasonalities. It is the tranquil times and not the crisis/volatile times that generates a significant and profitable contrarian strategy. The recent credit crisis and resulting stock market falls, resulted in extreme movements in some Greek stocks and testing of the contrarian strategy problematic, especially when portfolios are decile ordered. Our findings also highlight the importance of survivorship bias and also suggest that contrarian strategies that just use market beta may be ill-equipped to take into consider extreme market movements, illiquidity and short-sales constraints.     

Stock return reversal and continuance anomaly: new evidence from Hong Kong

Using weekly data, this article conducts a comprehensive analysis and presents new empirical evidences on the short-term stock return reversal and continuance anomaly in the Hong Kong stock market. We confirm that winner stocks behave differently from loser stocks in that the return reversal phenomenon is pervasive within past winner stocks only while past loser stocks tend to show weak return continuance. The arbitrage strategy can earn significantly positive contrarian profits, especially for small firms and illiquid stocks. The anomaly varies across different industries and is also sensitive to the market movement. Despite the existence of the anomaly, our results still in general suggest that the Hong Kong stock market is weak-form efficient because arbitrage trading costs would largely overwhelm the available profits in most cases.     

Evidence on the contrarian trading in foreign exchange markets

This paper investigates the existence and price impacts of contrarian behavior in the foreign exchange markets. By utilizing a nonlinear behavioral model where the chartists and fundamentalists coexist, evidence obtained from two sample periods significantly supports the existence of contrarian trading in the British pound, the Japanese yen and the German mark markets. The contrarian trading can only partially offset the price impacts of trend-followers, therefore the price impact of the chartists as a whole is destabilizing. The ability that the contrarians can counterbalance the extrapolation of the trend-followers differs across markets. Traders in the BP market have the highest tendency to contrarian strategy, which in turn contributes to the least deviations of the BP exchange rates departing from its PPP fundamentals. The fundamentalists' confidence in trade fades during large misalignments, which make the mean reversion function of the fundamentalists weak under the circumstances. We find the magnitudes of interventions will be affected by the price impacts of contrarians and their abilities on market stabilization.