Short sales,institutional investors and the cross-section of stock returns

Short-sale constraints are most likely to bind among stocks with low institutional ownership. Because of institutional constraints, most professional investors simply never sell short and hence cannot trade against overpricing of stocks they do not own. Furthermore, stock loan supply tends to be sparse and short selling more expensive when institutional ownership is low. Using institutional ownership as a proxy, I find that short-sale constraints help explain cross-sectional stock return anomalies. Specifically, holding size fixed, the under-performance of stocks with high market-to-book, analyst forecast dispersion, turnover, or volatility is most pronounced among stocks with low institutional ownership. Ownership by passive investors with large stock lending programs partly mitigates this under-performance, indicating some impact of stock loan supply. Prices of stocks with low institutional ownership also underreact to bad cash-flow news and overreact to good cash-flow news, consistent with the idea that short-sale constraints hold negative opinions off the market for these stocks.     

Migrate or not? The effects of regulation SHO on options trading activities

In this study, we investigate the effects of stock short-sale constraints on options trading by exploiting two US Securities and Exchange Commission rule changes under Regulation SHO: Rule 203 (locate and close-out requirements) and Rule 202T (temporary removal of short-sale price tests). We find that stock short selling activities decrease (increase) significantly after Rule 203 (Rule 202T) implementation, supporting the validity of Rule 203 (Rule 202T) as an exogenous increase (decrease) in short-sale constraints. Options volume increases significantly after Rule 203 went into effect and the result is more pronounced among firms with lower levels of institutional ownership and smaller options bid-ask spreads. Therefore, the evidence from Rule 203 suggests that investors may use options as substitutes for stock short sales when short selling is less feasible or more costly due to the locate and delivery requirements. In contrast, we find no significant change in the options trading volume of pilot stocks during the pilot program of Rule 202T. Overall, our results indicate that the impact of short-sale constraints on options trading varies with the types of constraints affected.     

Short-sale constraints and informational efficiency to private information: A natural experiment

Exploiting a regulatory change in short-sale constraints (Regulation SHO) as a natural experiment, this paper examines the effect of short-sale constraints on informational efficiency of stock prices to private information. I find that short-sellers act as informed traders prior to forthcoming analyst news and trade on negative private information. When short-sale constraints are relaxed for pilot stocks (treatment group), both trading volume and stock price sensitivity increase prior to the analyst announcement for bad news but not for good news, relative to that of nonpilot stocks (control group). The findings are consistent with the Diamond and Verrecchia model that predicts that short-selling increases the speed of adjustment of stock prices to private negative information. In the cross-section, the effect of Reg SHO is stronger in stocks of firms with weak and uncertain information environments (i.e., small firms and firms with high analyst forecast dispersion).     

Short-sale constraints and stock price crash risk: Causal evidence from a natural experiment

We examine the relation between short-sale constraints and stock price crash risk. To establish causality, we take advantage of a regulatory change from the Securities and Exchange Commission (SEC)’s Regulation SHO pilot program, which temporarily lifted short-sale constraints for randomly designated stocks. Using Regulation SHO as a natural experiment setting in which to apply a difference-in-differences research design, we find that the lifting of short-sale constraints leads to a significant decrease in stock price crash risk. We further investigate the possible underlying mechanisms through which short-sale constraints affect stock price crash risk. We provide evidence suggesting that lifting of short-sale constraints reduces crash risk by constraining managerial bad news hoarding and improving corporate investment efficiency. The results of our study shed new light on the cause of stock price crash risk as well as the roles that short sellers play in monitoring managerial disclosure strategies and real investment decisions.     

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。     

Short Selling and the Weekend Effect for NYSE Securities

Using short-sale transactions data, we examine the relation between short selling and the weekend effect. We do not find that short selling is more abundant on Monday than on Friday, even for stocks that have higher Friday returns. We find that short sellers execute more short-sale volume during the middle of the week, and that the positive correlation between short selling and returns on Monday is greater, on average, than the correlation on the other days of the week. Our results are robust to subsamples of stocks with larger weekend effects and stocks that do not have listed options.     

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 and the independence of business-related analysts: Evidence from an emerging market

This paper investigates whether short-sale deregulation improves analysts' independence in an emerging market where conventional mechanisms mitigating conflicts of interest are either ineffective or absent. Short selling reduces the effectiveness of analysts' favourable opinions in creating or sustaining overvalued stock prices, thus decreasing the incentives of institutional clients of brokerages to exert pressure on related analysts to initiate coverage and issue biased opinions. Using a difference-in-difference approach, we find strong evidence that stocks that are eligible for short sales experience a greater reduction in coverage by related analysts than stocks that are ineligible for short sales. When covered firms become eligible for short sales, the quality of forecasts and recommendations issued by related analysts improves considerably. Further analyses show that shortable firms with a significant reduction in related analysts' coverage are more likely to underperform and to experience stock price crashes in the future. Altogether, our results are consistent with short selling effectively restoring related analysts' independence in emerging markets.     

The Calm before the Storm

I provide evidence that stocks experiencing unusually low trading volume over the week prior to earnings announcements have more unfavorable earnings surprises. This effect is more pronounced among stocks with higher short‐selling constraints. These findings support the view that unusually low trading volume signals negative information, since, under short‐selling constraints, informed agents with bad news stay by the sidelines. Changes in visibility or risk‐based explanations are insufficient to explain the results. This evidence provides insights into why unusually low trading volume predicts price declines.     

Short selling of ADRs and foreign market short-sale constraints

We examine the effect of home market short-sale constraints on securities that also trade in other countries that have more liberal short-sale rules. In particular, we focus on the case of ADRs traded in the US, as in some cases, the home markets of these ADRs prohibit short selling. We find that short sellers more heavily trade ADRs from countries where short selling is prohibited than from markets where short selling is allowed. Furthermore, we find that the greater levels of short selling in ADRs with binding home-market constraints is driven by stocks with greater dispersion of investors’ opinion, low fundamentals-to-price ratios, and recent price increases. Our results support the hypothesis that short sellers target ADRs with home market short-sale constraints because these ADRs are more often subject to temporary misvaluation.     

Options, short-sale constraints and market efficiency: A new perspective

This paper undertakes a new investigation of the potential for options to mitigate short-sale constraints. I find that option introduction alleviates 79% of the price adjustment efficiency disparity between short-sale constrained and unconstrained stocks in relation to negative news. No significant improvement in adjustment efficiency is found in response to positive information. These results are robust to controls for endogeneity biases associated with the option introduction selection process. Further, I find evidence that post-option improvement in efficiency is similar in relation to private and public information. This suggests that short-sale constraint effects stem, at least in part, from an irrational, optimism bias or another behavioral source as suggested theoretically by Miller (1977). Collectively, these results suggest that options act as an effective substitute to short-sales, significantly contributing to the informational efficiency of the market.     

Short-sale constraints and stock price informativeness

Morck, Yeung, and Yu (2000), in their pioneering study of international differences in stock price synchronicity, emphasize the effect of market development on investors' ability to incorporate firm-specific information into prices. We use a unique institutional feature in the Hong Kong market to investigate one of the important tools investors use to do this and hence reduce stock price synchronicity: short selling. Examining the cross-sectional and time-series variation in short-sale constraints in the Hong Kong market, we find that after the removal of short-sale constraints, stock prices become more informative and move less in tandem with the market.     

Short selling activity,price efficiency and fundamental value of IPO stocks

In this study, we take advantage of the unique features of the Taiwan stock market, where short selling is forbidden within the first six months following an IPO. We examine the effects of short selling on IPO price efficiency and the relation between short selling activities and the fundamental value of IPO stocks. We find that price efficiency is improved with increased short selling after the lifting of short sale constraints on IPO stocks. We also show that short sellers tend to target IPO stocks with low fundamental ratios, but simultaneously avoid stocks with high transaction costs. In addition, we provide empirical evidence that short sellers focus more on temporary price fluctuations rather than temporary fluctuations in fundamentals.     

Short interest,institutional ownership,and stock returns

Stocks are short-sale constrained when there is a strong demand to sell short and a limited supply of shares to borrow. Using data on both short interest (a proxy for demand) and institutional ownership (a proxy for supply) we find that constrained stocks underperform during the period 1988–2002 by a significant 215 basis points per month on an equally weighted basis, although by only an insignificant 39 basis points per month on a value-weighted basis. For the overwhelming majority of stocks, short interest and institutional ownership levels make short selling constraints unlikely.     

Short‐Selling Risk

Short sellers face unique risks, such as the risk that stock loans become expensive and the risk that stock loans are recalled. We show that short‐selling risk affects prices among the cross‐section of stocks. Stocks with more short‐selling risk have lower returns, less price efficiency, and less short selling.     

Does media coverage deter firms from withholding bad news? Evidence from stock price crash risk

Spurred by the informational and disciplinary roles that the media fulfils, this study provides initial evidence on how higher media coverage is associated with a lower tendency of firms withholding bad news, proxied by stock price crash risk. Our main findings are robust to a battery of tests that account for endogeneity concerns including a difference-in-differences analysis based on newspaper closures that exogenously reduce media coverage and a regression-discontinuity design analysis based on the top band of Russell 2000 and lower band of Russell 1000 index stocks. Additional tests reveal that the negative relation between media coverage and stock price crash risk is concentrated within firms with more negative and novel news coverage and firms with higher litigation or reputation risks. We also find that media plays an important role in reducing future stock price crash risk when there is reduced monitoring by other external monitoring mechanisms such as external auditors, financial analysts, and institutional shareholders.     

Foreign and Local Institutional Ownership and the Speed of Price Adjustment

Abstract:  This paper examines the relation between the speed of price adjustment and stock ownership by foreign and local institutional investors using data from the Korean stock market. We show that returns of stocks with high foreign institutional ownership lead returns of stocks with low foreign institutional ownership, especially after foreign ownership restriction is lifted. Likewise, returns of stocks with high local institutional ownership lead returns of stocks with low local institutional ownership. These results support the idea that foreign institutional (local institutional) investors have faster access to or processing power of new information than local institutional (local individual) investors.     

Earnings Announcements,Differences of Opinion and Management Guidance

Berkman, Dimitrov, Jain, Koch, and Tice (2009) document a negative relationship between differences of opinion and earnings announcement returns, and this relationship is more pronounced when short‐sale constraints are likely to be high. These findings are interpreted as support for the theory in Miller (1977) that binding short sale constraints cause pessimists to be underrepresented in price formation. We conjecture that accounting information (i.e., earnings news) is likely to play a role in this returns pattern. After controlling for the level of earnings news, we find that the relationship between differences of opinion and stock returns is either eliminated or opposite from what is predicted by Miller's theory. Further, we present evidence that suggests the confounding effect of earnings news can be explained by (pessimistic) management earnings guidance. Our findings offer an alternative explanation for why low differences of opinion stocks earn greater abnormal returns around earnings announcements.     

The skinny on the 2008 naked short-sale restrictions

On July 15, 2008, the US Securities and Exchange Commission announced temporary restrictions on naked short sales of the stocks of 19 financial firms. The restrictions offer a unique empirical setting to test Miller’s (1977) conjecture that short-sale constraints result in overpriced securities and low subsequent returns. Consistent with Miller’s overpricing hypothesis, we find evidence of a positive (negative) market reaction to the announcement (expiration) of the short-sale restrictions. Announcement returns are higher for firms that appear to be subject to more naked short selling in the days immediately preceding the announcement of the restrictions. The restrictions are successful in eliminating naked short sales for the restricted stocks, but naked short sales increase dramatically for a closely matched sample of financial firms during the restricted period. We also find that the restrictions negatively impact various measures of liquidity, including bid-ask spreads and trading volume. From a public policy perspective, our findings suggest that, at a minimum, policymakers should pause when considering further short sale restrictions.     

Price Convexity and Skewness

This paper develops a model in which investors who are prohibited from short selling agree to disagree on the precision of a publicly observed signal. The model implies that the equilibrium price is a convex function of the public signal. The model predicts that (1) the stock price reacts more to good news than to bad news; (2) the skewness of stock returns is positively correlated with contemporaneous returns, but negatively correlated with lagged returns; (3) short sale constraints increase rather than decrease skewness; and (4) disagreement about information precision increases skewness. Empirical tests conducted find supportive evidence for all these predictions.