卖空交易与公司违约风险北大核心CSSCI

本文使用中国2010-2018年融券标的公司的卖空交易量来考察实际发生的卖空交易如何影响公司违约风险。本文借助转融通业务的开启构建准自然实验情境,缓解可能存在的内生性问题。研究结果表明卖空交易能够显著降低公司违约风险。卖空交易降低违约风险的主要机制之一是减少公司的新增融资。横截面差异检验发现卖空交易降低公司违约风险主要存在于控股股东私利侵占行为比较严重、融资约束程度较高和政府干预程度较高的公司之中。     

卖空机制对股票市场影响的研究初探

2010年3月31日,我国股票市场正式启动了融资融券业务,融资融券业务的推出标志着我国证券市场正式告别"单边市"时代,我国证券市场也具有了卖空机制,本文以卖空交易为研究对象,研究卖空交易对股票市场的相关影响,笔者认为我国融资融券业务的推出将极大增强我国股票市场的有效性,有利于我国股票市场稳步健康发展。     

卖空交易、市场行情与股价崩盘风险

本文构建了"暴涨暴跌"市场行情指数以区分股市异常波动与非异常波动行情,利用我国融资融券交易试点及五次扩容事件作为自然实验,精确分离出卖空交易对股价崩盘风险的独立效应。研究发现,虽然融资交易的杠杆效应会增大股价崩盘风险,但是卖空交易显著降低了股价崩盘风险;市场行情对卖空交易和融资交易的影响机制存在差异,"暴涨暴跌"市场行情加大了融资交易的杠杆效应对股价崩盘风险的增大程度,却显著提升了卖空交易对股价崩盘风险的降低作用。本文拓展了卖空交易经济功能的研究,并区分了股市异常波动(暴涨暴跌)和非异常波动行情对卖空交易降低股价崩盘风险功能的影响,研究结论对于完善融资融券制度、促进卖空交易功能发挥、完善资本市场监管具有重要的政策含义。     

融资融券交易提升了股市流动性吗?——来自A股市场的经验证据

融资融券交易对股市流动性的影响尚未形成一致结论,不过大多数学者的研究结论认为融资融券将提升股市流动性。本文基于沪深市场个股交易数据得出的实证结果表明:融资融券标的股票的流动性要显著高于非融资融券标的股票,融资融券交易对于个股流动性有着显著的提升作用,并且主要体现为融资买空对流动性的提升作用,而融券卖空对于流动性的提升作用并不明显。此外,融资融券交易事件日前后个股流动性的对比结果显示:融资融券交易推行后,个股的流动性水平较之前有了显著提高。之后应继续完善融资融券交易制度,促进融资和融券业务均衡发展。     

融券卖空、企业社会责任与企业价值

本文基于2010—2021年沪深A股上市公司数据，以我国融资融券制度和转融券制度为准自然实验，从卖空的事前威慑和事后惩罚视角，系统考察了卖空机制对企业社会责任的影响效应、传导机制及经济后果。研究发现，卖空机制引入、卖空进一步放松和实际的融券交易量均显著促进了企业社会责任。机制检验发现，卖空机制引入和实际的融券交易通过提高股价信息效率(信息效应)和降低盈余管理程度(治理效应)对企业社会责任发挥促进作用。进一步研究发现，卖空机制引入和实际的融券交易对企业社会责任的促进作用提升了长期的企业价值。研究结果表明，卖空机制对企业社会责任具有外部治理效应，支持了企业社会责任的“股东主义”观点。本文为卖空的外部治理效应提供了新证据，并对资本市场改革助力经济高质量发展具有重要的政策启示。     

高管减持如何影响投资者预期?——基于超额融券的经验证据

随着我国融资融券业务逐步扩容,投资者向证券公司融券卖出的卖空交易成为市场消化负面信息的重要机制。本文以高管减持事件窗口期的超额融券量为研究对象,采用事件研究法考察我国企业高管减持所任职公司股票对市场预期的影响。实证结果表明,相比估计期,高管减持窗口期超额融券量显著增长,并且减持比例越高或者减持金额越大,超额融券量越高,表明高管减持显著降低了外部投资者对公司股票的价值预期。进一步研究显示,良好的信息透明度能够显著降低高管减持对超额融券量的正向影响。本文用超额融券量直观地度量投资者预期变化,丰富和发展了高管减持经济后果的研究,对规范我国上市公司高管减持行为及监管部门完善相关监管规定具有启示意义。     

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。     

转融通后融资融券交易对我国股市的影响研究

本文以转融通试点初期沪深两市的试点股为样本,以沪深300指数代替整体市场形势,通过基于多元回归模型和Granger因果关系检验,探究了转融通后我国融资融券交易对股市的影响,发现融资买空交易显著影响市场流动性水平,融资买空交易和融券卖空交易量都显著影响市场波动水平,而市场流动性水平也会对融券卖空交易产生影响。     

融券卖空机制、转融券扩容与正反馈交易行为——基于A股市场基金的分析

本文使用MT指标度量基金正反馈交易的强度,以2013年两次转融券扩容为自然实验,探究融券卖空机制对A股市场基金正反馈交易行为是否具有抑制影响,实证研究发现融券卖空机制对基金正反馈交易行为具有显著抑制作用,在波动率更高或市值更大的股票中作用更强,但是市值边际影响递减。研究结果支持了信息效率假说,因此在融券与转融券有序扩容中,应加强信息披露监管,进一步发挥融券卖空机制可提高价格信息含量的优势。     

融资融券交易与市场价格发现——基于盈余公告漂移的实证分析

融资融券的推出是中国证券市场交易制度的一次结构性的变革,本文以第一批可以融资融券的90只股票为样本,选取盈余公告漂移异象作为研究标的,从理论和实践角度检验融资融券推出对市场价格发现的影响作用.我们发现,融资融券的推出使得投资者有更多的选择和手段对市场信息做出及时反应,A股市场的一个市场异象盈余公告漂移在融资融券后有显著减弱.最后本文利用融资融券制度的可卖空和杠杆交易特征构造了基于盈余漂移的交易策略.     

Which financial stocks did short sellers target in the subprime crisis?

Tracing the SEC ban on the short selling of financial stocks in September 2008, this paper investigates whether such selling activity before the 2008 short ban reflected financial companies’ risk exposure in the subprime crisis. Evidence suggests that short sellers sold short stocks that had the greatest asset and insolvency risk exposures, and that the short selling of financial firms’ stocks was not significantly greater than that of non-financial firms after we match them on firm size and insolvency risk. When the short ban was in effect, the market quality of financial stocks without subprime assets exposure had deteriorated to a larger degree than that of financial companies with subprime assets exposure. The findings imply that such a regulation may mute the market disciplining effects of investors and may also be seen as a counterweight to any perceived macro or systemic risk reduction benefits resulting from such a ban.     

Does capital market drive corporate investment efficiency? Evidence from equity lending supply

The increased equity lending supply (ELS) in the equity loan market, available for short sellers to borrow, exposes a firm to greater short selling threats. Considering short sellers' strong incentives to uncover firm-specific information and monitor managers, we hypothesize that short selling threats, proxied by ELS, enhance corporate investment efficiency. We find that ELS significantly reduces managerial tendencies to underinvest (overinvest) especially for firms prone to underinvest (overinvest). The effect of ELS on investment efficiency is stronger for firms with higher information asymmetry and weaker corporate governance, confirming short sellers' role in mitigating information and agency costs. However, short selling risk weakens the effect of ELS. Our evidence is robust to endogeneity checks and suggests that corporate investment can be driven by a particular capital market condition: the amount of lendable shares in the equity loan market.     

独立董事返聘与公司违规:“学习效应”抑或“关系效应”？

本文关注独立董事任期届满后离任、但经过一段“冷却期”后再次被原上市公司返聘的现象(“独立董事返聘”)。本文以2003—2016年沪深两市A股上市公司为样本,研究了独立董事返聘对公司违规的影响究竟是基于“学习效应”的抑制效果还是基于“关系效应”的助长效果。研究发现:(1)对独立董事返聘的公司而言,相对于冷却期,返聘期的公司违规显著更少(纵向对比);(2)返聘的独立董事首任期间,公司违规要显著低于冷却期(纵向对比);(3)相较无独立董事返聘、返聘人数更少的公司,返聘人数更多的公司违规显著更少(横向对比)。研究发现支持了“学习效应”假说,即独立董事返聘抑制了公司违规,并非是规避任期规定的手段。     

Margin trading,short selling,and bond yield spread

Using a quasi-natural experiment, this study examines the effects of margin trading and short selling on bond yield spread in China. It finds that both margin trading and short selling can reduce bond yield spread. Additionally, it finds that margin trading lowers firms’ debt ratios and increases their credit ratings, which explains the reduced spread. In other words, margin trading can impact investors’ decisions by revealing positive information about a firm. Another finding is that short selling lowers the bond yield spread by decreasing earnings management, suggesting that short selling has an impact on investors’ decisions through its effect on corporate governance. Our results suggest that margin trading transmits positive information and short selling impacts firms’ policies. These results provide support for future regulations of margin trading and short selling.     

Can short selling improve internal control? An empirical study based on the difference‐in‐differences model

Based on pilot margin trading in China, this study examines how short selling affects internal control quality in listed firms. Using the difference‐in‐differences approach, we find that compared with control firms, firms that are eligible for short selling significantly improve their internal control after they are designated as underlying securities. We consider the effects of state ownership and external auditors. The improvement in internal control is only significant for non‐state‐owned firms and firms audited by non‐Big 4 auditors. These findings indicate that short selling can improve firms’ internal control and play a role in their corporate governance.     

放松卖空管制能够抑制并购商誉泡沫吗？

本文以我国放松卖空管制作为切入点,系统检验了其对并购商誉泡沫的影响。研究发现,放松卖空管制之后,超额商誉显著下降,同时商誉资产也显著下降,且该效应在民营控股公司中更显著;机制检验发现,卖空通过吸引更多分析师跟踪、增加对管理者的激励来抑制商誉泡沫;进一步研究发现,在市场化水平较高、行业竞争度较低的情形下,卖空机制对商誉泡沫的抑制作用更强。本文的研究结论丰富了卖空和并购商誉领域的文献,并为以市场导向原则化解并购商誉泡沫提供了新思路和新范式。     

卖空者与内幕交易——来自中国证券市场的证据

本文研究上市公司内部人减持、年报、诉讼、分析师评级、停复牌以及高送转等重大公告前后卖空交易行为的变化,系统考察卖空者是否参与内幕交易以及何种因素影响卖空者参与内幕交易,发现卖空率较高的股票具有较低的未来收益,表明卖空者拥有信息优势,属知情交易者;卖空者拥有非常精确的择时交易能力,在重大利空公告前显著增加卖空量,而在利好公告前则显著减少卖空头寸,表明卖空者作为知情交易者的信息优势源自内幕消息;公司内、外部投资者的信息不对称程度越低或公司所在地的法治水平越高,卖空者参与内幕交易的行为就越少。因此,监管机构应密切关注公司重大消息发布前后卖空量的异常变动,同时,完善信息披露规则、健全证券分析师制度并强化法律法规的执行力度,才能有效防范卖空者参与内幕交易。     

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.     

Short Sellers and Financial Misconduct

We examine whether short sellers detect firms that misrepresent their financial statements, and whether their trading conveys external costs or benefits to other investors. Abnormal short interest increases steadily in the 19 months before the misrepresentation is publicly revealed, particularly when the misconduct is severe. Short selling is associated with a faster time‐to‐discovery, and it dampens the share price inflation that occurs when firms misstate their earnings. These results indicate that short sellers anticipate the eventual discovery and severity of financial misconduct. They also convey external benefits, helping to uncover misconduct and keeping prices closer to fundamental values.     

卖空机制的审计收费效应研究

卖空机制作为一种金融创新,如何在提高证券市场定价效率的同时,有效发挥外 部治理功能、改善公司治理、间接推动国内资本市场健康发展成为理论和实践中的一项重要 课题。运用多元回归模型对国内卖空机制改变审计风险、进而影响审计收费行为的实证检验表 明,随着股票卖空比率的上升,公司审计收费也相应增加。而股票卖空比率与公司审计费用受 制度环境影响显著,在市场化水平较高的地区,公司审计面临来自投资者更大的压力。此外, 公司审计收费与股票卖空比率的正相关关系会因卖空机制的存在变得更加显著。