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。     

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。     

知情交易概率与知情交易者跨期行为

在证券市场中,根据交易主体之间拥有信息的差异,可以将投资者分为拥有私有信息的知情交易者与不拥有私有信息的不知情交易者,知情交易者会利用自己的信息优势参与证券的买卖,从中获利.     

知情交易概率测算在内幕交易监管中的应用

内幕交易定义侧重信息分布状态,知情交易定义侧重信息认知状态,在立法和监管层面,内幕交易包含知情交易的内涵。信息优势是内幕交易监管困境的根源所在,知情交易概率模型从是否拥有信息的两种不同交易行为模式出发．有助于判断潜在的内幕交易行为,根据选取时间段变量、事件变量和财务指标变量的不同,为内幕交易监管选取重点目标提供参考。在监管实务操作中。强化信息核心、改革收盘机制、主张模糊界定等是必要的手段。     

证券市场内幕交易行为之经济学分析

证券市场中上市公司的收购兼并、增发等行为日益频繁和复杂,利用内幕信息进行非法交易并获利的行为也越来越多。作者通过运用经济学中效用函数理论对内幕交易行为进行分析,指出作为理性人的内幕交易者,除了扩大内幕交易得益、降低内幕交易实施成本外,也会通过各种手段来极尽所能地降低遭受处罚成本;而内幕交易者实施内幕交易的得益远远大于内幕交易的实施成本和所受到的惩罚,正是内幕交易行为频繁的原因。通过上述分析,作者提出了防范内幕交易行为的对策建议,即舆论监督和举证责任倒置。     

正反馈交易模型与中国股市价格波动--对DSSW模型的扩展讨论

DSSW模型描述了在理性交易者和非理性交易者数量相等的设定下,正反馈交易者的交易行为以及金融资产价格的波动情况.针对中国股市特征,建立了扩展的六状态DSSW模型,讨论了信息交易者利用信息优势,借助正反馈交易者的跟风行为,操纵股价大幅波动,获取超额收益的行为.利用该模型分析了“庄家”内幕交易的五个阶段及其特征,据此提出建议:完善信息披露机制,加强对特殊波动股票的监控,改变股票盈利模式,树立价值投资理念.     

论完善内幕交易案件的代表人诉讼制度

内幕交易损害了证券市场的公平竞争秩序和广大投资者的利益,内幕交易者应当承担侵权责任。内幕人员不仅包括传统内幕信息知情人,还包括临时内幕信息知情人以及推定的内幕信息知情人。本文认为,应对内幕交易行为提起人数不确定的代表人诉讼,并对原告的确定、诉讼管辖、赔偿额的确定、判决的效力及执行等问题予以探讨。     

信息结构、风险偏好与盈余操纵行为——一次实验研究的结论

运用实验方法构建具有不同信息结构的市场环境,研究风险偏好与外部监管环境对盈余操纵行为的影响。实验结果表明,外部监管环境对盈余操纵行为具有显著约束作用;信息不对称时,信息成本将加重操纵程度,内幕交易者借助信息优势,或者回避风险,或者获取超额收益;非内幕交易者存在过度自信表现;信息结构不影响风险偏好者的操纵意愿。但与外部惩戒力共同影响其最终收益。     

卖空威胁、公司融资扩张战略与违规行为

利用中国推出融资融券业务的准自然实验机会,本文以2010—2016年中国A股上市公司为样本,使用双重差分模型研究放松卖空限制对企业违规行为的影响。研究发现,融券业务允许市场中的知情投资者挖掘企业负面信息进行卖空,形成有效的卖空威胁,从而震慑企业,显著降低其发生违规行为的概率。具体而言,卖空交易行为跟企业违规行为的严重程度正相关;卖空交易行为能显著降低企业的超额收益率;当企业有进一步融资需求或并购扩张战略需求时,卖空威胁对企业的震慑作用更为显著。研究表明,融券业务带来的卖空威胁是企业外部监管的重要机制。     

卖空机制与分析师乐观性偏差——基于双重差分模型的检验

本文主要研究卖空机制对分析师乐观性偏差的影响。基于我国开通融资融券交易的自然实验构建双重差分模型(DID),检验发现:对于融资融券标的公司,引入卖空机制显著降低了分析师盈余预测的乐观性偏差,并提高了盈余预测的准确度;当机构私利引起的利益冲突较轻时,卖空机制对分析师乐观性偏差的抑制作用更为明显。本文研究结果表明,资本市场交易制度的完善促使财务分析师提供更准确的预测信息,进而有助于提高资本市场效率。     

Short selling around dividend announcements and ex-dividend days

We examine short selling around dividend announcements and ex-dividend dates. Contrary to our initial expectation, we do not find abnormally high short-selling activity prior to announced dividend decreases, which runs counter to the argument that short sellers have the ability to acquire private information before its public dissemination. However, we find that the common negative relation between current short selling and future daily returns prior to unfavorable dividend announcements is similar to the negative relation during non-event times, suggesting that dividend announcements do not provide unusual trading opportunities for informed traders (Gonedes, 1978, and Benartzi et al., 1997). Around ex-dividend dates, we do find abnormal short selling, which may be explained by the return pattern around ex-dividend days documented by Lakonishok and Vermaelen (1986), who suggest that demand for a particular stock by dividend capture traders drives stock prices above their fundamental value thus providing a profitable trading opportunity for short sellers. Consistent with this conjecture, we find that both the level of short selling and the return predictability of short selling is markedly higher on and after the ex-dividend day than during non-event times.     

Short-Selling Prior to Earnings Announcements

This paper examines short‐sales transactions in the five days prior to earnings announcements of 913 Nasdaq‐listed firms. The tests provide evidence of informed trading in pre‐announcement short‐selling because they reveal that abnormal short‐selling is significantly linked to post‐announcement stock returns. Also, the tests indicate that short‐sellers typically are more active in stocks with low book‐to‐market valuations or low SUEs. The levels of pre‐announcement short‐selling, however, mostly appear to reflect firm‐specific information rather than these fundamental financial characteristics. We believe that these results should encourage financial market regulators to consider providing more extensive and timely disclosures of short‐selling to investors.     

Insider trading,stock return volatility,and the option market's pricing of the information content of insider trading

We find strong evidence that net insider selling is positively associated with future stock return volatility, consistent with insider selling increasing outside investors’ uncertainty. The positive effect of net insider selling is significantly stronger when the volatility is measured around the earnings announcement. Apparently, option prices do not fully reflect the information content of insider trading for future volatility. More specifically, we find no evidence that option traders adjust the implied volatility for the insider trading effect in a timely manner. Consequently, net insider selling is significantly associated with future option straddle returns and delta neutral returns.     

Early Movers Advantage? Evidence from Short Selling during After‐Hours on Earnings Announcement Days

We examine short sellers’ after‐hours trading (AHT) following quarterly earnings announcements released outside of the normal trading hours. Our innovation is to use the actual short trades immediately after the announcements. We find that on these earnings announcement days, there is significant shorting activity in AHT relative to shorting activity both during AHT on nonannouncements days and during regular trading sessions around announcements. Short sellers who trade after‐hours on announcement days earn an excess return of 0.82% and 1.40% during before‐market‐open (BMO) and after‐market‐close (AMC)sessions, respectively. The magnitude of these returns increases to 1.48 (3.92%) for BMO (AMC) earnings announcements with negative surprise. We find that the reactive short selling during AHT has information in predicting future returns. Short sellers’ trades have no predictive power if they wait for the market to open to trade during regular hours. In addition, we find that the weighted price contribution during AHT increases with an increase in after‐hours short selling. Overall, our results suggest that short sellers in AHT are informed. Our findings remain robust using alternative holding periods and after controlling for macroeconomic news announcements during BMO sessions.     

Inside the <Emphasis FontCategory="SansSerif">“</Emphasis>black box<Emphasis FontCategory="SansSerif">”</Emphasis> of private in-house meetings

We examine information content and related insider trading around private in-house meetings between corporate insiders and investors and analysts. We use a hand-collected dataset of approximately 17,000 private meeting summary reports of Shenzhen Stock Exchange firms over 2012–2014. We find that these private meetings are informative and corporate insiders conducted over one-half of their stock sales (totaling $8.7 billion) around these meetings. Some insiders time their transactions and earn substantial gains by selling (purchasing) relatively more shares before bad (good) news disclosures while postponing selling (purchasing) when good (bad) news is to be disclosed in the meeting. Finally, we conduct a content analysis of published meeting summary reports and find that the tone in these reports is associated with stock market reactions around (1) private meetings themselves, (2) subsequent public release of private meeting details, (3) subsequent earnings announcements and (4) future stock performance.     

How are shorts informed? : Short sellers,news, and information processing

We find that a substantial portion of short sellers' trading advantage comes from their ability to analyze publicly available information. Using a database of short sales combined with a database of news releases, we show that the well-documented negative relation between short sales and future returns is twice as large on news days and four times as large on days with negative news. Further, we find that the most informed short sales are not from market makers but rather from clients, and we find only weak evidence that short sellers anticipate news events. Overall, the evidence suggests that public news provides valuable trading opportunities for short sellers who are skilled information processors.     

Sell-side analyst heterogeneity and insider trading

This study explores insider trading patterns under different earnings surprises. After controlling for stock market liquidity and earnings announcements returns, we show that insiders sell more aggressively depending on the heterogeneity of analysts whose EPS forecasts are met or beaten to camouflage their trades. Specifically, insiders sell more shares of their company sooner after the publication of earnings when top analysts' forecasts are met or beaten. Consistent with the informed trading literature, insiders strategically select these moments because the stock price impact is low and the legal scrutiny of their trades is minimal. To support this result, we employ an exogenous drop in firms' analyst coverage due to the closure or merger of brokerage houses. Furthermore, in line with the camouflage incentives, by selling after top analysts' forecasts are met or beaten, stock prices adjust slowly to insider trades. Finally, we show that the incentives of insiders to hide their trades are concentrated in opportunistic insiders and members of the top management team, who are more likely to bear the costs of selling shares after positive news.     

Why do insiders trade? Evidence based on unique data on Swedish insiders

In this paper, we examine if corporate insiders have other motives for trading besides exploitation of private information. Our results show that insiders’ portfolio re-balancing objectives, tax considerations and behavioral biases play the most important role in their trading decisions. We also find that insiders who have allocated a great (small) proportion of their wealth to insider stock sell more (less) before bad news earnings disclosures. Finally, insider selling is informative for future returns among those insiders who have the greatest proportion of wealth allocated to insider stocks.     

Are Short Sellers Informed? Evidence from the 2007–2008 Subprime Mortgage Crisis

This paper examines the short selling activities around financial firms’ announcements of asset write‐downs during the 2007–2008 subprime mortgage crisis. We find that short sellers accumulate short positions prior to write‐down announcements, and that stocks experience significantly negative returns around such announcements. These results suggest that the return predictability of short interests is due to short sellers’ informational advantage. Furthermore, we show that short sellers increase their positions significantly in the announcement month and keep increasing their positions afterward, suggesting the feedback effect of the disclosed write‐downs on financial firms’ existing exposures. The valuable information contained in the short interest should encourage regulators to mandate stock exchanges disclose short selling activities more frequently.     

事前披露能够降低董监高减持的获利能力吗?——基于中国“减持新规”的实证检验

"事前披露"能否降低董监高交易的信息优势?中国证监会于2017年5月修订并实施的"减持新规"首次为上述命题的检验提供了独特的研究场景。通过"事件研究法",本文对"减持新规"颁布前后的董监高减持行为进行研究,考察事前披露减持计划是否会削弱董监高减持时的信息优势。实证结果表明,"减持新规"实施后董监高减持的短期超常回报显著低于"减持新规"实施前,这说明事前披露会抑制董监高交易的择时能力。进一步研究发现,当公司信息质量较差、所处地区的市场化程度较低、成长性较高、减持规模较大时,事前披露对董监高减持获利能力的削弱作用更强;"减持新规"实施对董监高减持超常回报的削弱主要体现在交易日与减持计划披露日间隔短的减持样本中。本文不仅在实证层面上验证了"事前披露"可以降低董监高交易的信息优势,丰富了内部人交易研究文献,也为我国"减持新规"的实施效果提供了证据和建议。