特质信息含量对股价波动性影响的实证研究

本文以股价非同步指标量化股价中公司特质信息的含量,在有效剔除掉市场和行业系统信息成分后,基于面板数据模型实证研究我国上市公司股价中特质信息含量与其波动性之间的关系。结果表明：近年来我国上市公司股价中的特质信息含量基本呈逐年递增趋势。与发达国家资本市场相比,这一比例仍然偏低;越多的公司特质信息被市场捕获,股价越能及时充分地反映上市公司内在价值的变化,从而有利于抑制股价的异常波动。     

分析师研究报告负面信息含量与股价同步性

本文基于文本分析法,选取2019-2021年A股上市公司相关数据,实证检验分析师研究报告负面信息含量与股价同步性之间的关系。研究结果表明:(1)分析师研究报告负面信息含量越高越能显著抑制公司的股价同步性;(2)当研究报告由明星分析师分析撰写时,分析师研究报告负面信息含量与股价同步性的负相关关系更加显著;(3)负面信息含量越高,引起投资者关注度越高,真实信息更容易融入股价,从而降低了股价同步性;(4)在公司信息透明度较低时,分析师研究报告负面信息含量对股价同步性的抑制作用越强。本文对了解分析师在资本市场中发挥的作用以及维持资本市场的健康发展具有重要的理论和实践意义。     

证券市场非完全知情交易者是风险助推者吗?——基于Kyle模型的分析

跟庄散户等非完全知情交易者的交易行为会影响证券市场上的其他参与者。本文基于Kyle模型的拓展研究表明:当市场流动性下降时,知情交易者会减少交易;部分知情的噪声交易加入后会使得知情交易者的预期收益下降;当非完全知情交易者的委托单流恰好完全跟踪股票价值时,内幕信息持有者的信息将不能操纵股价波动。从抑制知情交易者的内幕交易行为的角度讲,非完全知情交易者有助于推动证券市场交易的透明化、公正化,进而减少整个市场潜在的金融风险。     

股价同步性:信息效率还是噪音偏差?——基于分析师跟进的证据

股价同步性反映了股价中包含是信息还是噪音一直是学术界极具争议的话题。本文运用2004~2013年分析师研报数据实证分析了股价同步性与信息效率之间的关系。研究发现,股价同步性与信息效率存在正向关系,即分析师发布报告的股票股价同步性越低,报告中反映信息效率的公司特有信息含量越低,同时发现这种正向关系源于投资者对明星分析师研报的过度反应。结果表明,我国股票市场的投资者存在"追星"的选择性偏差,股价较低同步性包含了更多的噪音。研究结论为我国证券行业规范投资者行为提供了一个新的切入点,为建立健全投资者教育体系给出了一定的政策建议。     

事务所规模、审计行业专长与知情交易概率

外部审计的作用在于提高公司的信息披露透明度,减少信息不对称,以保护投资者利益。本文从知情交易概率视角出发,研究了外部审计在减少信息不对称方面所发挥的作用。研究结果发现,国内"十大"审计的公司,以及由具有审计行业专长的事务所审计的公司,知情交易概率更低,而且行业专长的国内十大(非十大)审计的公司的知情交易概率也低于不具有行业专长的国内十大(非十大)。进一步检验还表明,在机构投资者持股的公司中,事务所规模和审计行业专长能够更有效减少知情交易概率。     

企业公司治理、金融市场化与股价崩盘风险研究

本文基于我国沪、深两市A股上市公司的数据,从企业内部微观治理和外部宏观环境视角出发,系统研究了终极所有权、金融市场化对股价崩盘风险的影响效应,得出如下研究结论:一是终极控制股东现金流权越高、两权分离度越低,则代理成本与信息不透明度越低,公司股价崩盘风险越小;二是所处地区金融市场化水平越高,公司股价崩盘风险越低;三是金融市场化在终极所有权与股价崩盘风险的影响关系中具有负向调节效应,较高的金融市场化水平能够有效发挥外部治理作用,削弱了两权分离度对公司股价崩盘风险的影响.本文丰富并拓展了对终极所有权、金融市场化与股价崩盘风险影响因素的相关研究,对我国公司治理发展、金融体制改革以及金融风险防范具有重要启示意义.     

股价信息含量与企业融资行为研究——基于中国上市公司的经验证据

本文利用中国上市公司1998—2017年的样本数据,实证检验了股票价格中包含的公司特质信息含量对企业融资行为的影响。研究结果表明:股价信息含量对企业股权融资增长率存在显著的促进作用,该影响在国有企业和民营企业中均成立;股价信息含量对负债增长率的促进作用体现于短期负债,对长期负债并无显著影响;相比国有企业,股价信息含量对民营企业短期负债增长率的影响更为显著;股价信息含量对民营企业融资行为的影响主要体现在低代理成本的企业中。进一步分析表明,经理人学习意愿越强,投资者认知水平越低,股价信息含量对企业融资行为的正向影响就越显著,从而支持"经理人学习"和"投资者认知"的内在机制。     

并购重组前的知情交易行为研究

并购重组中基于内幕信息的知情交易行为既是监管重点,也是学术界关注的热点问题。本文以2006—2020年我国上市公司并购重组事件为样本,考察并购重组前的知情交易行为对并购公告收益的影响。研究发现：并购重组前的知情交易行为引发了主并公司股价的提前反应,从而降低了并购公告时的市场反应,这一现象是由内幕信息泄露引起,且内幕信息主要来源于包括员工在内的公司内部人,而非机构投资者。进一步分析表明,改善信息环境可以有效缓解并购重组的信息泄露问题,体现为知情购买交易的信息泄露效应受到分析师跟踪、审计质量和问询函制度的有效制约。本文研究深化了现有的并购重组内幕交易行为研究,为实施精准监管和防范内幕交易等政策提供了一定参考和依据。     

是谁影响了股价下行风险:有形信息VS无形信息

股价下行作为资本市场的普遍现象,在极端情况下会对投资者财富和公司声誉造成巨大冲击,因此受到学界、业界和监管层的高度关注。本文选取2007-2016年我国A股上市公司股票为样本,研究了不同信息对股价下行风险的影响,在此基础上考察了过度自信和损失厌恶两种不同的投资者行为是否会影响信息与股价下行风险之间的关系。研究发现:(1)有形信息显著降低了股价下行风险,而无形信息对股价下行风险的影响并不显著;(2)投资者的过度自信水平越高,有形信息与股价下行风险的负向关系越弱;(3)投资者的损失厌恶程度越高,有形信息与股价下行风险的负向关系越强。本文的研究不仅为投资者的投资决策提供了一个良好的风险管理思路,也为监管层的政策制定提供了相关的理论依据。     

企业关联、信息透明度与股价特征

由于声誉和私下沟通机制的存在,关系型交易降低了交易双方对高质量公开信息的需求,并且关系型资产的专用性,也提高了外界通过市场信息对交易行为进行类比解读的成本。因此,依赖关系进行交易的上市公司的股价中包含的公司特有信息将减少,体现为更高的股价同步性和较高的大涨或大跌风险。通过对我国2004年至2007年间首发上市的151家民营企业上市后三年股价特征的考察,本文提供了支持上述推测的经验证据。本文的研究结果为企业间关系如何影响股价特征这一研究领域提供了新的视角和经验证据。     

Business strategy,stock price informativeness,and analyst coverage efficiency

We examine how business strategy affects stock price informativeness which in turn influences analyst coverage efficiency. Using stock price synchronicity and the probability of informed trading as proxies for stock price informativeness, we show that stock prices of prospectors are less informative than those of defenders. Next, we explore two channels through which business strategy influences analyst coverage efficiency. We first test and find support for an information transfer channel, i.e., the higher stock price synchronicity of prospectors facilitates more information transfer by analysts, resulting in higher analyst coverage efficiency of prospectors than defenders. Next, we test and find support for an informed trading channel, i.e., the higher probability of informed trading on stocks of defenders intensifies competition between informed traders and analysts. Such competition adversely affects analyst coverage efficiency, leading to lower analyst coverage efficiency of defenders than prospectors. Our findings are robust to an array of robustness checks including 2SLS/IV tests, differences‐in‐difference tests, and high‐tech industry sensitivity analyses.     

Information-based stock trading and managerial incentives: evidence from China's stock market

This paper uses stock price informativeness, or information-based stock trading, to help explain the pay–performance sensitivity (PPS) of chief executive officer (CEO) compensation in China's listed firms. We argue that higher stock price informativeness, which we measure by the probability of informed trading, helps and encourages shareholders to incentivize the top management team based on stock market performance. The regression results support our argument and show that a higher level of stock price informativeness is associated with higher CEO PPSs. Moreover, the impact of stock price informativeness on CEO incentives is stronger for privately controlled listed firms than it is for state-controlled listed firms. The results also hold when information asymmetry is approximated by the accuracy and dispersion of the earnings forecasts made by financial analysts.     

Short sales constraint and SEO pricing

We examine the influence of SEC's Rule 105 on informed trading and the information content of stock prices around an SEO's offer day. We show that constraints on short sales inhibit informed trading and hamper incorporation of information into stock prices for offers whose traders have private adverse information and without options listing. The constraints contribute to increased price uncertainty and higher market sensitivity to seller-initiated trading. After controlling for other causes of SEO discounts, we find that the decrease in information content of stock prices just before an offer day has a significant impact on the SEO's value discount.     

A dynamic strategy of the informed trader with market manipulation

This paper considers stock price manipulation by a dynamic informed trader. We provide a simple proof of the existence of manipulation in a market in a standard sequential trade model. We also give the lower bound of the number of trading periods for the existence of manipulation in equilibrium and show that if the number of trading periods is larger than that lower bound, every equilibrium involves stock price manipulation. Irrespective of the prior of the market maker, if the informed trading probability is high enough, every equilibrium involves manipulation.     

An Empirical Analysis of Illegal Insider Trading

Whether insider trading affects stock prices is central to both the current debate over whether insider trading is harmful or pervasive, and to the broader public policy issue of how best to regulate securities markets. Using previously unexplored data on illegal insider trading from the Securities and Exchange Commission, this paper finds that the stock market detects the possibility of informed trading and impounds this information into the stock price. Specifically, the abnormal return on an insider trading day averages 3%, and almost half of the pre-announcement stock price run-up observed before takeovers occurs on insider trading days. Both the amount traded by the insider and additional trade-specific characteristics lead to the market's recognition of the informed trading.     

The impact of informed trading on corporate liquidity

The purpose of this paper is to analyze the impact of informed trading on corporate liquidity. Although theory posits an inverse relation between informed trading and firm liquidity, there is relatively little evidence on precisely how this relation is established or maintained. The trading model of Easley et al. (J. Finance 51 (1996) 1405) is employed to estimate the probability of informed trading and to identify specific days of informed trading using posterior probabilities. The results show that corporate liquidity, both in terms of spreads and depths, is a decreasing function of the probability of informed trading. The main finding is that spreads narrow and depths increase on actual information days even after controlling for variations in price, volume, and volatility.     

Heterogeneously informed trading and the stock market efficiency during the COVID-19 pandemic

This study investigates the U.S. stock market efficiency from the symmetric and asymmetric perspectives during the COVID-19 pandemic. We explore that the pandemic boosts (hurts) the information role of symmetrically (asymmetrically) informed trading. Specifically, we find that the epidemic outbreak and infection scale strengthen (weaken) the stock return reaction to symmetrically (asymmetrically) informed trading. Evidence also indicates that the effect of symmetrically (asymmetrically) informed trading on stocks' permanent price shocks and price informational efficiency is enhanced (impaired) during the pandemic. Moreover, all these effects are consistently more intensive to informed buys.     

Trading on inside information: Evidence from the share-structure reform in China

We examine stock trading activities in days before Chinese listed firms made public announcement to start share-structure reform. There is significant evidence that, relative to a benchmark period, institutional investors bought more event firms’ shares in the last two trading days prior to announcement. Randomization tests show significant differences in institutional trading activities between event firms and matched control firms, which suggests that some institutions had inside information. Moreover, large trades account for a significant proportion of daily stock price changes in the last 2 days. The evidence is consistent with the prediction by Holden and Subrahmanyam (1992) that, when multiple informed investors acquire the same piece of information, they will trade aggressively. We also find that over the reform period, the median share value change of event firms is 6% higher than that of control firms. Our findings have important implications for enforcement of insider trading regulations in China.     

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.