内幕交易监管：国际经验与中国启示

内幕交易违反了金融市场的公平原则,降低了资本市场的效率,但是由于其金融交易的特殊性,使得它在监管上存在一定的难度。本文在梳理内幕交易行为的理论基础、对内幕交易监管的争议进行讨论的基础上,从内幕人认定、内幕信息认定、内幕交易行为认定、防范措施以及法律制裁与救济等五个不同的维度对美国、日本、欧盟和我国的内幕交易法律制度进行比较分析,从而总结我国法律在内幕交易规制方面的不足,并相应地提出改进的建议。     

The Favourite‐Longshot Bias, Bookmaker Margins and Insider Trading in a Variety of Betting Markets

This paper verifies the existence of the favourite‐longshot bias in a variety of sports betting markets where odds are set by bookmakers, but the precise pattern of the bias is not identical. Evidence is found to support a central prediction of the Shin (1993) model, which asserts that bookmakers are impelled to create a bias in their odds because of the presence of insider traders: that margins increase with the number of competitors.     

内幕交易的经济学分析

本文探讨了中国市场的内幕交易理论,在此基础上提出了4个可检验的假说:(1)内幕交易在中国必定存在;(2)内幕交易在中国比成熟市场更加严重;(3)重大事件中内幕交易的严重程度和管理层付出呈正比关系;(4)内幕交易多围绕利好消息。利用1078个并购重组事件和其他上市公司重大事件为样本,本文运用事件研究法,证实了上述假说。在此基础上,提出了中国内幕交易立法和监管的思路。     

Parimutuel contests with strategic risk-sensitive bettors

Existing models in the parimutuel betting literature typically explain betting data by either assuming a single, representative bettor with certain risk preferences or by assuming that a number of risk neutral bettors compete strategically within a game theoretic framework. We construct a theoretical framework of parimutuel markets in which we model both strategic interaction and individual bettor risk preferences, distinguishing between sophisticated insiders and recreational outsiders. We solve this model analytically for the optimal insider betting amount in a static symmetric Nash equilibrium. A new data set of 126 million individual horse race bets in New Zealand from 2006 to 2014 allows us to calibrate the model. We find that insiders (those betting $100 or more) outperform outsiders by 7.5% in terms of realized returns. The best fit of the model to the data is obtained when insiders are assumed to be risk neutral and to have an information advantage of 0.08 in probability terms. This finding provides empirical support for the common assumption of risk neutrality in strategic interaction models of parimutuel betting.     

Searching for the favourite-longshot bias down under: an examination of the New Zealand pari-mutuel betting market

This paper tests for the presence of the favourite-longshot bias in a new setting. This bias #150 the tendency for bettors to underbet favourites and overbet longshots #150 has been found in most studies of pari-mutuel and bookmaking betting markets in the USA, the UK and Australia. However, there is growing evidence that in at least some pari-mutuel betting markets there is no favourite-longshot bias. This paper examines the previously unexplored New Zealand pari-mutuel betting market on horse races for evidence of this bias. Utilizing a large sample of recent New Zealand thoroughbred horse races, it is found that while early, off-track bettors price this bias into odds, late (on-and off-track) bettors eliminate much of the bias by the close of betting. That is, the results reinforce the view that not all pari-mutuel betting markets are characterized by a favourite-longshot bias at the close of betting. Evidence is also found that late bettors in this market are smart bettors.     

Price Limits, Information Acquisition, and Bid–ask Spreads: Theory and Evidence

A number of futures markets use price limits which, in effect, preclude trade from occurring at prices outside certain exogenous bounds. Noting that such markets are characterized by heterogeneously informed traders, whereas previous work on price limits assumes symmetrically informed traders, we examine the effects of price limits in a setting where market participants are asymmetrically informed. We find that imposing price limits generally lowers the quality of information acquired in equilibrium, but lowers bid–ask spreads as well. Thus, depending on the relative weights placed by society on liquidity versus price efficiency, there may exist a set of price limits that are most efficient in achieving a trade-off between liquidity and informational efficiency. We perform empirical tests of some implications of the model using cross-sectional data on price limits. We find that price limits are strongly negatively related to both price volatility and trading volume. Though other explanations for our empirical findings cannot be ruled out, these results are not inconsistent with the model's implication that price limits should be tighter for contracts which offer greater profit potential for informed traders.     

On insider trading and belief evolution

In a market with stochastic demand with seller competition at most one seller can acquire costly information about demand. Other sellers entertain idiosyncratic beliefs about the market demand and the probability that an informed seller is trading in the market. These idiosyncratic beliefs co-evolve with the potential insider’s inclination to acquire information.True demand expectations (in the Bayesian sense) are not evolutionarily stable when beliefs, via revelation, can be used to commit to more aggressive behavior. The commitment effect fades away in large markets and has the same direction for both strategic substitutes and complements. Whether one observes an insider, in the long run, depends on information costs. For strategic substitutes insider activity benefits the whole population whereas the uninformed sellers could gain even more than the insider.     

What Is Common Among Return Anomalies? Evidence from Insider Trading

For a broad set of anomalies, we establish a common pattern of underreaction to information contained in preceding insider trading activity. Our main analysis focuses on the anomalies' short legs, which generate persistent negative abnormal returns. For stocks in the short legs, future returns are systematically related to the information signal contained in preceding insider trading activity, indicating underreaction. For insider trading information, we consider the possibility of net buying, net selling, and no trading (or silence). The underreaction effect is economically significant, with the most negative signal accounting for an average of 71% of short-leg returns. This underreaction effect survives numerous robustness checks and remains important after accounting for investor sentiment, information environment, and limits to arbitrage.     

Testing equity market efficiency around terrorist attacks

This article uses the nine major bombings since 1998 that have been attributed to Al Qaida to examine market efficiency, including a test of rumours that investors traded with advance knowledge of attacks. Analysis of these related, but individually unexpected, events confirms markets are semi-strong efficient: it now takes well under a trading day to fully price in a completely unexpected attack. On balance, markets also proved strongly efficient with no conclusive evidence of insider trading.     

Information–driven trading at the Prague Stock Exchange: Evidence from Intra–Day Data

Many observers argue that informed and insider trading is widespread in the emerging financial markets of transition countries, yet rigorous treatment of this issue has been virtually non–existent. The current paper estimates the extent of informed trading on the Prague Stock Exchange (PSE) using intra–day transaction data. Our estimates confirm that the average share of informed trading is equal to 0.32, which is high relative to developed markets and varies considerably among stocks. Using the Easley et al. (1996) approach on the very best segment of the PSE we obtained a high average probability of informed trading. Since data used in this study cover the period after the major attempts to improve market regulations, our results indicate that the PSE needs further strengthening to recover credibility and to become a real source of corporate financing. JEL classification: G14, G15.     

融券制度与内部人寻租——来自准自然实验的经验证据

内部人寻租一直以来是理论与实务界关心的重点,如何有效抑制内部人寻租行为是资本市场的重大课题。本文以内部人交易度量内部人寻租,分析了融券制度对内部人寻租的影响。研究发现:(1)融券制度对内部人寻租有显著抑制作用,并且融券规模越大,内部人寻租越少。(2)相比于国有企业,非国有企业当中融券制度对内部人寻租的抑制作用更加明显。本文还将内部人交易分方向进行回归,结果显示融券制度对内部人寻租的抑制作用主要体现在卖出方向上。本文进一步分析了融券制度影响内部人寻租的路径,发现“竞争效应”和“信息效应”是融券制度影响内部人寻租的两条重要路径。本文考虑了竞争性解释——分析师关注的作用,发现分析师关注并不能影响本文结论的正确性;本文还利用反面事实推断、倾向得分匹配、反向因果检验等方法,确保实证结论的稳健性。本文的研究结果,丰富了内部人寻租的特征及影响因素研究,有利于市场监管部门加强对内部人寻租行为的控制;扩充了有关融券制度的文献,为卖空制度的推行及完善提供理论依据。     

内幕交易的经济学分析

该文探讨了中国市场的内幕交易理论,在此基础上提出了4个可检验的假说:(1)内幕交易在中国必定存在;(2)内幕交易在中国比成熟市场更加严重;(3)重大事件中内幕交易的严重程度和管理层付出呈正比关系;(4)内幕交易多围绕利好消息.利用1078个并购重组事件和其他上市公司重大事件为样本,该文运用事件研究法,证实了上述假说.在此基础上,提出了中国内幕交易立法和监管的思路.     

Information Efficiency in Betting Markets: a Survey

The concept of information efficiency is central to many studies of financial markets, and these studies have been well surveyed to date. A betting market is an example of a simple financial market, but one which offers researchers the added advantage that it is characterized by a well-defined termination point at which each asset (or bet) possesses a definite value. In consequence, it is much more convenient to use this particular context to formulate tests of information efficiency, and from these tests to draw useful conclusions. This paper surveys the rapidly growing literature which has to date addressed this issue of information efficiency in betting markets.     

Informed manipulation

In asymmetric information models of financial markets, prices imperfectly reveal the private information held by traders. Informed insiders thus have an incentive not only to trade less aggressively but also to manipulate the market by trading in the wrong direction and undertaking short-term losses, thereby increasing the noise in the trading process. In this paper we show that when the market faces uncertainty about the existence of the insider in the market and when there is a large number of trading periods before all private information is revealed, long-lived informed traders will manipulate in every equilibrium.     

A game theory model of regulatory response to insider trading

We develop a model which can help in explaining the evolving regulatory regime around insider trading. We form a simple sequential game-theoretical model of insider trading transactions and, utilizing Monte Carlo simulation to determine equilibrium, we show that costly investigations and low penalties incentivize traders to engage in illegal transactions. While the model helps to explain stiffer action by regulatory bodies, the question remains as to whether the elevated penalty levels are sufficient to prevent further insider trading.     

Efficient Selection and Insider Contracting Groups: a Comment on the Yarbrough & Yarbrough Paper

Beth & Robert Yarbrough's paper reviews and augments an extensive literature analyzing how insider trading groups support the process of exchange. They argue that these groups efficiently adapt to changes in the transacting environment. Yarbrough & Yarbrough's argument is compelling for groups operating in a free and open civil society but not when competition among groups is impaired by barriers to entry and externalities. This article considers whether insider trading groups are able to reach a steady-state equilibrium and presents a number of historical and contemporary examples in which insider trading groups plant the seeds of their own destruction.     

The Favourite-Longshot Bias and Market Efficiency in UK Football betting

It is shown that the individual fixed-odds betting market on UK football exhibits the same favourite-longshot bias as that found in horse-racing. The bias appears both in betting on results (home win, away win or draw) and in betting on specific scores, and there are certain trading rules which appear to be profitable. Poisson and Negative Binomial regressions are carried out to estimate the mean number of goals scored by a team in a match with given market odds for the various outcomes. Tables of odds for individual scores are derived and these appear to fit the actual outcomes far better than those of the bookmaker.     

Market efficiency and continuous information arrival: evidence from prediction markets

Two regularities in financial economics are that prices underreact to news events and that they display short term momentum. This article tests for the presence of these regularities in prediction markets offered by the betting exchange Betfair on the 2008 Ryder Cup Golf Competition. Betfair offered in play prediction markets on the individual match play pairings and on the Cup result, with trading being virtually continuous in all markets. Modelled probabilities of the Cup result were updated continuously using trades in the individual match play pairings. These probabilities were then compared with the probabilities of the Cup result implied by odds in that market. The odds in the market for the Cup result underreact to both good and bad news that is provided by changes in the odds in the markets for the individual pairings. Further, these modelled probabilities Granger cause changes in the probabilities of the Cup result implied by odds in the market on that outcome. In addition, economically and statistically significant evidence of momentum is found in the odds in the market on the Cup result.     

上市公司内部人交易披露延迟及其经济后果研究——来自上海股票市场的经验证据

文章研究了我国上市公司内部人交易信息披露延迟的现状及其影响因素,以及披露延迟对内部人交易市场反应的影响。研究发现,整体而言,内部人交易存在披露延迟;交易披露延迟时间的长短与交易方向、交易是否处于信息敏感期、公司流通股比例、交易规模有关;在信息披露延迟严重的买入样本组,内部人职务对披露延迟产生了影响。市场给予内部人卖出股票负面评价而对买入股票的反应不显著;内部人交易的市场反应不受信息披露延迟影响。     

The effects of insider trading on insiders effort in good and bad times

We analyze the effects of insider trading on insiders' effort decisions and on the value of firms. We consider a situation in which the final output of a firm and the productivity of managerial effort will depend on whether the firm is in a good or a bad state. When the state is not verifiable, the managerial contract cannot be made explicitly contingent on it: consequently, a contract that does not allow for insider trading would lead to the insiders' facing the same incentive scheme in good and bad times. Under a contract that allows for insider trading, however, insiders will buy shares on receiving (ahead of the market) good news and will sell shares on receiving bad news; consequently, they will end up facing different incentive scheme in good and bad times. Whether this effect is desirable depends on how the marginal productivity of managerial effort in good times compares with that in bad times. In particular, we show that allowing insider trading may improve managers' effort decisions and consequently may increase corporate value and benefit shareholders.