Impact of correlated private signals on continuous-time insider trading

A model of continuous-time insider trading in which a risk-neutral in-sider possesses two imperfect correlated signals of a risky asset is studied.By conditional expectation theory and filtering theory,we first establish three lemmas:normal corre-lation,equivalent pricing and equivalent profit,which can guarantee to turn our model into a model with insider knowing full information.Then we investigate the impact of the two correlated signals on the market equilibrium consisting of optimal insider trading strategy and semi-strong pricing rule.It shows that in the equilibrium,(1)the market depth is constant over time;(2)if the two noisy signals are not linerly correlated,then all private information of the insider is incorporated into prices in the end while the whole information on the asset value can not incorporated into prices in the end;(3)if the two noisy signals are linear correlated such that the insider can infer the whole information of the asset value,then our model turns into a model with insider knowing full information;(4)if the two noisy signals are the same then the total ex ant profit of the insider is increasing with the noise decreasing,while down to O as the noise going up to infinity;(5)if the two noisy signals are not linear correlated then with one noisy signal fixed,the total ex ante profit of the insider is single-peaked with a unique minimum with respect to the other noisy signal value,and furthermore as the noisy value going to O it gets its maximum,the profit in the case that the real value is observed.

Do Auditors Postpone Reporting in Response to Insider Trading？ A Korean Perspective

How do auditors react to insider trading in client firms？ This paper examines the effects of insider trading on the audit report date. Insiders tend to urge managers to manage earnings to make more profits through trading their own firm＇s shares. If auditors play an important role in monitoring managers, they may pay more attention to insider trading, which may delay the filing of audit reports. We find that the more the insiders trade their stocks, the longer the audit report lag is. In addition, to address the effectiveness of auditors＇ efforts to prevent managers from earnings management, we test whether an extra effort by auditors can reduce aggressive accounting. We also find that auditors deter aggressive accounting by stretching report lag in response to insider trading, implying that auditors＇ efforts weaken insiders＇ opportunistic behavior. This study contributes to the literature by providing evidence that insider trading is a significant determinant of the audit report lag. We suggest that auditors are interested in insiders＇ activity and it can enhance the quality of accounting information.

Merger Announcement Effects and the Amendment of Insider Trading Laws in Brazil

Although Brazil has a long history of having insider trading laws （IT laws） in place and became the first emerging country to enforce the IT laws （Bhattacharya ＆ Daouk, 2002）, criminal sanctions and hefty monetary penalties were only made possible by the amendment of its laws against IT on October 31, 2001. We study the stock price effects of merger announcements made by 151 firms over two periods, before and after the change of IT laws. Our empirical results suggest that target firms attained positive price run-ups in pre-announcement windows before, but not after, the legal regime change. While acquiring firms had strong positive pre-announcement reactions in both legal regimes, the abnormal returns （AR） decreased in the more stringent legal regime. These results indicate that more stringent IT laws may deter IT and improve market efficiency in an emerging country.

Existence of Linear Strategy Equilibrium in Insider Trading with Partial Observations

This paper investigates a linear strategy equilibrium in insider trading in continuous time allowing market makers to know some information on the value of a stock. By the use of filtering theory,the authors prove that in a monopoly market, there exists a unique equilibrium of linear strategy of intensity in a closed form, such that the insider can make positive profits and at which, all of the private information on the value of the stock is released; and the more accurate the information on the value of the stock observed by the market makers, the less the positive profits are made by the insider, and even go to zero. However, there is no Nash equilibrium in a Cournot competition market between two insiders if they both adopt a linear strategy of intensity.

Sequential Fair Stackelberg Equilibria of Linear Strategies in Risk-Seeking Insider Trading

This paper develops a sequential fair Stackelberg auction model in which each of the two risk-seeking insiders has an equal chance to be a leader or follower at each auction stage. The authors establish the existence, uniqueness of sequential fair Stackelberg equilibria （in short, FSE） when both insiders adopt linear strategies, and find that at the sequential equilibria such two insiders compete aggressively that cause the liquidity of market to drop, the information to be revealed and the profit to go down very rapidly while the trading intensity goes substantially high. Furthermore, the authors also give continuous versions of corresponding parameters in the sequential FSE in closed forms, as the time interval between auctions approaches to zero. It shows that such parameters go down or up approximately exponentially and all of the liquidity of market, information and profit become zero while the trading intensity goes to infinity. Some numerical simulations about the sequential FSE are also illustrated.

Insider Trading with a Random Deadline under Partial Observations:Maximal Principle Method

For a revised model of Caldentey and Stacchetti(Econometrica,2010)in continuous-time insider trading with a random deadline which allows market makers to observe some information on a risky asset,a closed form of its market equilibrium consisting of optimal insider trading intensity and market liquidity is obtained by maximum principle method.It shows that in the equilibrium,(i)as time goes by,the optimal insider trading intensity is exponentially increasing even up to infinity while both the market liquidity and the residual information are exponentially decreasing even down to zero;(ii)the more accurate information observed by market makers,the stronger optimal insider trading intensity is such that the total expect profit of the insider is decreasing even go to zero while both the market liquidity and the residual information are decreasing;(iii)the longer the mean of random time,the weaker the optimal insider trading intensity is while the more both the residual information and the expected profit are,but there is a threshold of trading time,half of the mean of the random time,such that if and only if after it the market liquidity is increasing with the mean of random time increasing.

“Swimming Ducks Forecast the Coming of Spring”—The predictability of aggregate insider trading on future market returns in the Chinese market

This study systematically examines the ability of aggregate insider trading to predict future market returns in the Chinese A-share market. After controlling for the contrarian investment strategy, aggregate executive(large shareholder)trading conducted over the past six months can predict 66%(72.7%) of market returns twelve months in advance. Aggregate insider trading predicts future market returns very accurately and is stronger for insiders who have a greater information advantage(e.g., executives and controlling shareholders).Corporate governance also affects the predictability of insider trading. The predictability of executive trading is weakest in central state-owned companies,probably because the "quasi-official" status of the executives in those companies effectively curbs their incentives to benefit from insider trading.The predictive power of large shareholder trading in private-owned companies is higher than that in state-owned companies, probably due to their stronger profit motivation and higher involvement in business operations. This study complements the literature by examining an emerging market and investigating how the institutional context and corporate governance affect insider trading.

Impact of macroeconomic policy uncertainty on opportunistic insider trading

The macroeconomic policy environment affects the internal governance of microenterprises,which may provide opportunities for management to benefit from stock sales while decreasing its motivation to manipulate stock transactions.Using a sample of Chinese A-share listed companies from 2007 to2018,we study the impact of macroeconomic policy uncertainty on opportunistic insider trading.The results show that macroeconomic policy uncertainty helps restrain the opportunistic trading of shares held by management.When macroeconomic policies are uncertain,enterprises improve their internal governance.Furthermore,strengthening equity governance helps reduce management’s opportunistic use of the uncertainty of the policy environment,highlighting the advantageous effect of macroeconomic policy uncertainty and helping regulators standardize managerial behavior and promote the governance effect of macroeconomic policy.

Probability of informed trading during the COVID‑19 pandemic:the case of the Romanian stock market

Using data from the Bucharest Stock Exchange,we examine the factors influencing the probability of informed trading(PIN)during February—October 2020,a COVID-19 pandemic period.Based on an unconditional quantile regression approach,we show that PIN exhibit asymmetric dependency with liquidity and trading costs.Furthermore,building a customized database that contains all insider transactions on the Bucharest Stock Exchange,we reveal that these types of orders monotonically increase the infor-mation asymmetry from the 50th to the 90th quantile throughout the PIN distribution.Finally,we bring strong empirical evidence associating the level of information asym-metry to the level of fake news related to the COVID-19 pandemic.This novel result suggests that during episodes when the level of PIN is medium to high(between 15 and 50%),any COVID-19 related news classified as misinformation released during the lockdown period,is discouraging informed traders to place buy or sell orders condi-tioned by their private information.

Asymmetric Information, Heterogeneous Prior Beliefs and Market Regulation

This paper studies the trading behavior of an irrational insider and its influence on the market equilibrium in the presence of market regulation.We find that the market with only one insider with private information is almost close to a strong efficient market,under the condition of market regulation.In the equilibrium,the probability of the insider being caught trading with private information is zero,which shows that the reasonable behavior of the regulator is to essentially give up regulation.But the market efficiency and the irrational trader’s trading intensity all greatly improve because of the existence of the market regulation.

The Impact of Initial Public Offering Lockup Expirations on Liquidity:Evidence from Chinese Stock Market

Previous empirical evidence on the liquidity effect to the lockup expiration is mixed. A sample from Chinese listed firms is adopted and contributes to better understand this effect in emerging markets. The spread and illiquidity significantly increases around lockup expiration in China. Furthermore, the liquidity reaction to firms' disclosure quality is explicitly related. The results confirm that higher disclosure quality is significantly associated with lower abnormal spread and illiquidity impact. The effect of lockup expiration shares on liquidity proxies differs in firm disclosure quality. Identifying the factors affecting liquidity around such events may help regulators develop policies to provide investors with greater confidence in their investments.