#br# 融资融券加大了沪深股市波动吗*

融资融券设计初衷是通过融资加强市场流动性和通过融券提供投资者规避价格下跌风险的金融工具，改善由供求关系严重失衡导致市场巨幅震荡的局面，实现资本市场长期稳定的目标。实际操作中，融资融券疏通货币市场和资本市场间的资金流动，撬动巨额资金涌入股市；融资规模扩张过快而融券做空力量薄弱，业务结构发展严重失衡，导致两融业务具有“小冲击、大波动”的金融加速效应，放大了外部冲击引起股价上涨和下跌的幅度。协整回归分析表明，两融业务规模的扩张和收缩对上证指数涨跌具有显著的同向影响。TGARCH事件模型结果进一步证实融资融券从稳定股价到加剧波动的功能变化。随着标的股票扩容和业务常规化，两融业务导致股市投机过度，加剧了沪深两市的资产价格异动，没有达到平抑波动的设计预期。     

Short sale constraints and the information content of trading

We examine changes in the information content of trading when short sale constraints between prohibition and restriction exist on a stock exchange. This is made possible by a unique institutional arrangement at the Stock Exchange of Hong Kong. It maintains a list of stocks which can be sold short under regulations. Stocks not on the list are prohibited from short selling. The list is revised on a quarterly basis based on predetermined criteria. We find that the probability of information-based trading (PIN) significantly increases when a stock is added to the list. Further analysis shows that this is mainly because uninformed traders are driven out of the market. Elimination of uninformed traders also causes the aggregate trading volume to decrease rather than increase. In comparison, the PIN does not change when a stock is dropped from the list. We also find that market liquidity, measured by volatility and bid–ask spreads, slightly decreases when a stock is added to the list and significantly increases when a stock is dropped from the list. Possible explanations are discussed.     

融资融券交易的市场冲击效应研究——基于中国台湾证券市场的经验与启示

融资融券交易是证券市场的重要组成部分,它的推出会对整个市场产生何种影响是非常值得研究的问题.文章利用中国台湾证券市场的融资融券交易数据,从市场流动性与波动性角度研究融资融券交易对整个市场的冲击效应.研究结果表明,融资买空交易有助于提升整个市场的流动性水平,在一定程度上可以改善市场流动性水平相对不足的状况,但融券卖空交易对市场流动性水平没有显著影响;融资买空与融券卖空交易并未显著影响整个市场的波动性水平.文章建议证券监管部门可以将融资融券交易保证金率作为市场调控工具,通过适时调整保证金率调控整个市场,避免市场出现大幅震荡.     

The relation between the informational content of implied volatility and arbitrage costs: Evidence from the Oslo Stock Exchange

This study investigates the proposition that volatility of stock returns can be predicted from the volatility implied by options on the Oslo Stock Exchange (OSE), conditional on the ability to perform arbitrage. Insights into the relation between the informational content of implied volatility and arbitrage cost can be distilled from Oslo Stock Exchange data. For Norwegian firms, options and their underlying stock trade on the Oslo Stock Exchange and have an overlapping set of market makers thereby lowering the cost of arbitrage. Other components of arbitrage trading costs, liquidity and dispersion of stock return volatility, vary widely across Norwegian firms. Moreover, restriction on the short selling of stock in Oslo allows further insight into the role of arbitrage costs in determining the informational content of implied volatility. The results yield support for the arbitrage cost hypothesis: the lower the arbitrage cost between the stock and the option, the greater the informational content of implied volatility.     

融资、融券交易及其波动对股价稳定性的影响一致吗*

本文区分并讨论了融资交易、融券交易及二者的波动对标的股价稳定性影响的不一致性。研究表明,融资交易提高了标的股价的整体稳定性却加剧了股价异常下跌频率,而融券交易对股价整体稳定性及异常下跌频率并不存在显著影响。更重要的是,融资交易的异常波动加剧了股价的不稳定,而融券交易的异常波动则有助于提高股价稳定性。本文的政策启示在于,应采取比较“温和”的方式调控融资交易以避免融资交易的过度波动加剧标的股价的不稳定。     

卖空机制、股价信息含量与暴跌风险--基于融资融券交易的经验证据

文章利用我国逐步推出融资融券交易的自然实验机会,运用双重差分的研究设计,考察了卖空机制对股价反映负面消息效率的影响。文章以2007-2012年的数据为样本研究发现：相对于非标的股票,融资融券标的股票在成为标的之后,其股价对市场的向下波动及时做出了调整,使得股价对市场正负向波动反应之间的不对称性显著降低,表明标的股票更加及时和充分地吸收了有关公司价值的负面信息;同时,相对于非标的股票,融资融券标的标的股票在成为标的之后,其股价暴跌风险显著降低。文章结果表明,我国股市推出融资融券交易后,卖空机制提高了市场对标的股票负面消息的定价效率。     

关于我国股市知情交易水平及其性质的实证研究

基于Easley、Hvidkjaer和O'Hara的序贯交易模型与PIN (Probability of Information-based Trading,基于信息的交易比率)指标对我国股市知情交易情况进行的实证分析研究结果表明:(1)我国股市信息不对称程度较高;(2)由于知情交易者利用坏消息的能力有限且流动性交易水平较高,我国股市知情交易比率并不太高;(3)知情交易比率与后续期间股票收益率的负相关性,表明我国股市中市场操控型知情交易比较严重.因此,我们认为应进一步完善上市公司的信息披露制度,降低投资者之间的信息不对称程度,同时确保流动性投资者参与股市的积极性;在引入做空机制时应慎重考虑和综合权衡,避免不适当地增加流动性投资者所承担的逆向选择风险水平,降低股市的流动性供给和风险分散功能;证券市场监管部门应进一步加强对异常交易活动的监控,加大对市场操纵行为的打击力度,以确保我国证券市场的健康发展.     

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。     

Option implied beta and option return

We study the information content of option-implied betas for future equity option returns, using data on the S&P 500 index options and all of the component stock options. We find a significantly strong relation between option-implied betas and option returns cross-sectional. The paper presents evidence that call (put) option returns increase (decrease) with the option-implied betas of the underlying stock. A trading strategy of buying high (low) implied beta call (put) option portfolio and selling low (high) implied beta call (put) option portfolio generates a statistically and economically significant return. Our results are robustly persistent even after controlling for various cross-sectional effects and are not explained by the risk factors in asset pricing.     

连续竞价市场的股权结构、非对称信息与流动性

本文采用分笔交易的高频数据研究了股权结构对指令驱动的连续竞价市场中流动性和非对称信息的影响。研究表明,机构投资者对股票流动性有正的影响,且机构投资者能够显著减少交易过程的信息不对称程度,从而降低流动性成本。以国有股权和法人股权为代表的公司内部人对股票流动性没有显著影响,但能够降低交易过程的信息不对称程度,对减少流动性成本有积极作用。上市公司持股比例越分散,信息不对称程度越低,流动性成本越低。     

中国股市隐性交易成本影响因素分析

在电子指令驱动的交易制度下,中国股票价格、市场深度、知情交易概率、信息冲击、股价波动和买卖指令的不平衡性,都是影响隐性交易成本的因素;中国股市流动性、波动性和有效性,都对隐性交易成本产生影响,即流动性差、有效性低、波动性高会导致隐性交易成本增大.这一结论从实证上得到了验证.因此,隐性交易成本是衡量股票市场运行效率的一个综合性指标.     

融券约束和市场定价效率*——基于我国股票市场转融通的准自然实验证据

本文从融券约束的视角出发，研究我国股票市场融券机制对标的股票价格发现效率的影响。相比于融券交易量，融券约束可以更好地识别融券机制的作用。因为它可以从交易渠道、信息渠道、外部监管渠道对股价产生影响。笔者利用转融通的实施作为准自然实验，识别出了融券约束放松后标的股票价格发现效率的变化。实证结果显示融券约束放松后：（1）在市场下跌的情况下股价的共同趋势增强，意味着此时股价中包含的个股特质性信息含量降低，而市场上涨时则不存在这种效应；（2）股价对市场信息的反应速度增快；（3）股价更加接近随机游走，即股价的可预测性降低。本文的政策启示是，适当降低融券约束、扩大机构投资者比例、保持较高的融券交易准入门槛以及加强投资者教育可以促进融券机制发挥积极作用。     

The role of short selling threat in corporate environmental disclosure strategies: Evidence from China

Using staggered deregulation of short sales constraints in the Chinese capital market, this study investigates how short selling threat related to corporate environmental disclosure strategies. Our study finds that pilot firms experience a larger increase in hard disclosures, and a larger decrease in soft disclosures after short selling deregulation. Specifically, the increase in hard disclosure is found primarily at good environmental performers, whereas the decrease in soft disclosure is primarily found at poor environmental performers. Further analysis shows that the increase in hard disclosure and the decrease in soft disclosure is significantly more pronounced at firms that are covered by small number of media and analysts, with low institutional ownership and stock liquidity. Overall, our findings suggest that firms might change the type of environmental disclosure to mitigate their exposures to short selling threat, and provide evidence of the disciplining effect of short sales on environmental disclosures.     

A theoretical analysis of institutional investors' trading costs in auction and dealer markets

This paper compares trading costs for institutional investors subject to liquidity shocks, in auction and dealer markets. The batch auction restricts the institutions' ability to exploit informational advantages because of competition between institutions when they simultaneously submit orders. This competition lowers aggregate trading costs. In the dealership market, competition between traders is absent but private information is revealed by observing the flow of successive orders and so reduces aggregate trading costs. We analyse the relative effects on trading costs of competition and information revelation in the two systems and derive a parameter inequality which determines which system has lower costs.     

管理者交易的市场择时能力对市场流动性的影响

利用国泰安数据服务中心数据,采用事件研究法,考察中国上市公司中管理者买入交易和卖出交易对我国股票市场流动性的影响,结果显示:管理者买入后的市场流动性减弱,归因于管理者与其他市场参与者之间的信息不对称;管理者卖出降低管理者的股权,提高市场流动性,信息不对称减弱。管理者在市场交易比较活跃的日期交易,可能是因为在高的市场交易量下能隐藏管理者的私人信息。     

Insider trading with public and shared information

We study the impact of public information and shared information on traders' trading behavior in the context of Kyle's (1985) speculative market. We suppose that there are four types of traders in our model: one insider, M outsiders, liquidity traders, and market makers. We explicitly describe the unique linear Nash equilibrium and find that public information harms the insider but benefits the outsiders and noise traders. Also, the market is more efficient because of the existence of public information.     

Information advantage,short sales,and stock returns: Evidence from short selling reform in China

We study short selling around earnings announcements and examine the potential sources of their information. Using unique daily aggregate short selling transactions in China, we find that short sellers significantly increase (decrease) their short positions before negative (positive) earnings surprise. In addition, abnormal high short selling is significantly associated with negative post-earnings announcement stock returns. The findings suggest that short sellers, on average, are informed and sophisticated traders and they can exploit profitable opportunities contained in earnings announcements. Finally, we find that stocks with poor governance or more insiders have higher (lower) abnormal short selling in negative (positive) earnings surprise, indicating private information leakage from firms with weak governance; which is consistent with the tipping argument. Our findings have important policy implications for capital market regulation in China.     

The determinants of exchange settlement practices and the implication of volatility smile: Evidence from the Taiwan Futures Exchange

This paper proposes that the Taiwan Futures Exchange (TAIFEX) adopts a linear extrapolation method to set the settlement price for the Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX) options with less liquidity and thin trading. The empirical results indicate that the settlement-price-determined implied volatility is a smile function, consistent with the pattern of the market-price-determined implied volatility. Moreover, we examine the influence of economic factors on the TAIFEX's decision regarding the parameters of implied volatility function. Compared with the economic determinants of market-force-driven volatility parameters, the TAIFEX inappropriately values the impacts of the parameters of prior days, current stock returns, distribution of stock returns, long-term measurement of the stock market trend, market transaction cost, and time to maturity.     

Liquidity commonality in order-driven trading: evidence from the Athens Stock Exchange

We examine the presence of liquidity commonality in the order-driven Athens Stock Exchange (ASE). Unlike the majority of liquidity commonality studies that focus on the bid–ask spread, our analysis extends deeper in the Limit Order Book, providing insight on the price impact of both small and large trades. We utilize a 6-month FTSE/ATHEX-20 intraday data set to estimate the liquidity factor model of Chordia et al. (2000). To this end, we conduct single-equation analysis as well as panel data analysis with the use of two-way clustered errors, correcting for simultaneous firm and time correlations. Moreover, we apply standard principal component analysis on stock liquidities to extract the marketwide liquidity component. We find that liquidity commonality is low at the bid–ask spread, whereas it increases deeper in the book; consequently, large traders face liquidity risks associated with both individual stock and marketwide illiquidity. Moreover, our empirical evidence hints that liquidity commonality is asynchronous, suggesting that the ASE trading process includes various levels of information speed. Our analysis contributes to the understanding of liquidity commonality in order-driven trading, especially in emerging markets like the ASE where trading activity is limited and information speed is low.     

成交风险、交易成本、逆向选择风险与投资者订单选择

本文利用多元对教条件自田归计数模型讨论了交易概率、交易成本以及选择成本等市场微观结构因素对中国证券市场投资者订单选择的影响.实证研究发现:(1)交易成本的增加会削弱投贵者递交指令的积极性,当成交风险较大时,投资者更偏好市价订单;(2)由于中国证券市场订单类型较为单一,逆向选择风险对投资者订单选择行为并无显著性的影响;(3)在同质信息的驱动下不同类型订单之间具有显著的持续和交叉相关性.