Short sales constraints and price adjustments to earnings announcements: Evidence from the Hong Kong market

This study examines how short sales constraints affect the stock price adjustment to the release of public information in the Hong Kong Stock Exchange. Using a unique feature of this market that allows us to directly investigate the impact of short sales restriction, we find the following. First, non-shortable stocks react more strongly to the publication of negative information than shortable stocks do. Second, non-shortable stocks are overpriced before negative earnings announcements. Hence, part of the strong market reaction of non-shortable stocks on announcement day could be due to the correction of such overpricing. Third, the prices of non-shortable stocks reverse following the announcement of negative information, suggesting that investors overreact to negative information on announcement day. Fourth, it takes longer for the prices of non-shortable stocks to adjust to negative earnings information. On the whole, our results support the research that finds short sales restrictions reduce the efficiency of stock markets.     

ON THE INFORMATIONAL EFFECT OF SHORT‐SALES CONSTRAINTS: EVIDENCE FROM THE TOKYO STOCK EXCHANGE

Using a database of stock lending fees for Japanese centralized margin transactions, I show that short‐sales constraints reduce the adjustment speed of stock prices to negative information before the announcements of revised earnings forecasts disclosed by firms in the Tokyo Stock Exchange from July 1998 to December 2001. I find that the cumulative abnormal returns (CARs) of the stocks with high short‐sales costs are insensitive to negative information on pre‐announcement days, but the CARs of these stocks become significantly lower than the CARs of the stocks with low short‐sales costs when the announcements reveal negative information to the public.     

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.     

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.     

Do option markets undo restrictions on short sales? Evidence from the 2008 short-sale ban

The effectiveness of any sanction depends on the costs of avoiding its restrictions. We examine whether bearish option strategies were substitutes for short sales during the September 2008 short-sale ban. We find a significant diminution in option volumes and a significant increase in option bid-ask spreads for banned stock relative to unbanned stock during the ban period. Apparent violations of the put-call parity bound became significantly more frequent for banned stocks during the ban period. We conclude that the ban acted as an effective restriction on trading in options.     

Are Short Sellers Informed? Evidence from the 2007–2008 Subprime Mortgage Crisis

This paper examines the short selling activities around financial firms’ announcements of asset write‐downs during the 2007–2008 subprime mortgage crisis. We find that short sellers accumulate short positions prior to write‐down announcements, and that stocks experience significantly negative returns around such announcements. These results suggest that the return predictability of short interests is due to short sellers’ informational advantage. Furthermore, we show that short sellers increase their positions significantly in the announcement month and keep increasing their positions afterward, suggesting the feedback effect of the disclosed write‐downs on financial firms’ existing exposures. The valuable information contained in the short interest should encourage regulators to mandate stock exchanges disclose short selling activities more frequently.     

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.     

Comparing the information in short sales and put options

Prior work shows that both short sales and put options contain information about future stock prices. In this study, we compare the return predictability in short sales to the return predictability in put options. The motivation for this comparison is based on the theoretical argument that informed traders can choose between short sales and put options when establishing short positions in a particular stocks. Results in this paper suggest that the underperformance of stocks with high short-selling activity is approximately four times larger than the underperformance of stocks with high put-option activity. While stocks that are most likely to face binding short-sale constraints drive the underperformance caused by put-option activity, we still find that short sales are generally more informative about future prices.     

The impact of naked short selling on the securities lending and equity market

This paper examines the impact of naked short selling on equity markets where it is restricted to securities on an approved list. Consistent with Miller's (1977) intuition, stocks with the highest dispersion of opinions and short sale constraints are the only stocks to exhibit significant and negative abnormal returns in the post-event period. We also find slightly higher stock return volatility and a small reduction in liquidity when naked short sales are allowed. Overall, it impairs market quality (liquidity and volatility), although there appears to be some improvement in price efficiency in stocks with high short sale constraints.     

Short-sale constraints and the idiosyncratic volatility puzzle: An event study approach

Using three natural experiments, we test the hypothesis that investor overconfidence produces overpricing of high idiosyncratic volatility stocks in the presence of binding short-sale constraints. We study three events: IPO lockup expirations, option introductions, and the 2008 short-sale ban on financial firms. Consistent with our prediction, we show that when short-sale constraints are relaxed, event stocks with high idiosyncratic volatility tend to experience greater price reductions, as well as larger increases in trading volume and short interest, than those with low idiosyncratic volatility. These results hold when we benchmark event stocks with non-event stocks with comparable idiosyncratic volatility. Overall, our findings suggest that biased investor beliefs and binding short-sale constraints contribute to idiosyncratic volatility overpricing.     

The financial distress pricing puzzle in banking firms

This paper examines whether the financial distress pricing puzzle observed for non-financial firms is also observed for financial firms and how this puzzle differs according to the extent of short-sale constraints. By using the eight distress measures developed for financial firms, we find that there is a strong negative relation in the cross-section between financial distress and subsequent bank stock returns, regardless of adjustment for risk. However, this distress pricing puzzle is statistically significant only for high short-sale constrained banks, but not for low short-sale constrained banks. Thus, short-sale constraints are at least one non-risk attribute that causes the distress pricing puzzle for financial firms. We also find that despite its simple form, compared to the other complex distress measures, non-performing loans (NPLs) are the most informative in predicting future bank stock returns as well as bankruptcy and failure.     

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).     

Sell on the news: Differences of opinion,short-sales constraints,and returns around earnings announcements

Miller [1977. Risk, uncertainty, and divergence of opinion. Journal of Finance 32, 1151–1168] hypothesizes that prices of stocks subject to high differences of opinion and short-sales constraints are biased upward. We expect earnings announcements to reduce differences of opinion among investors, and consequently, these announcements should reduce overvaluation. Using five distinct proxies for differences of opinion, we find that high differences of opinion stocks earn significantly lower returns around earnings announcements than low differences of opinion stocks. In addition, the returns on high differences of opinion stocks are more negative within the subsample of stocks that are most difficult for investors to sell short. These results are robust when we control for the size effect and the market-to-book effect and when we examine alternative explanations such as financial leverage, earnings announcement premium, post-earnings announcement drift, return momentum, and potential biases in analysts’ forecasts. Also consistent with Miller's theory, we find that stocks subject to high differences of opinion and more binding short-sales constraints have a price run-up just prior to earnings announcements that is followed by an even larger decline after the announcements.     

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.     

Linear beta pricing with efficient/inefficient benchmarks and short-selling restrictions

We provide two security pricing models that can be used when short sales of risky securities are not permitted. The first model uses a benchmark located on the expected return-standard deviation efficient frontier without short sales and presents security expected returns as a weighted linear function of two betas, one induced by the benchmark and the other adjusting for the short-sale constraints. The second model uses a benchmark that is inefficient relative to the efficient frontier, does not allow short sales, and expresses security returns as a weighted linear function of three betas:one induced by the inefficient benchmark, and the other two adjusting simultaneously for the short-sales restrictions and the benchmark's inefficiency.These results complement the linear pricing models that link expected returns and betas by allowing, for efficient or inefficient expected return-standard deviation, benchmarks with restricted short sales.     

Banks, Bears, and the Financial Crisis

We test whether short selling is destabilizing comparing distressed financial firms to other firms using NYSE transactions records covering 4 years including the recent financial crisis. Aggressive short-selling is sometimes destabilizing by some measures, but its impact is small, vanishes quickly, is not necessarily larger for distressed firms or during the crisis, and is accompanied by other stabilizing effects. The evidence does not validate theoretical predictions from models of destabilizing speculative or predatory trading. Aggregate short-selling is largely unrelated to market-wide investor sentiment, credit risk, and ex ante volatility. Aggressive liquidation of long positions typically has more impact than short selling. Thus, the data cannot justify the restrictions on short sales of financial stocks imposed in September 2008.     

The dispersion anomaly and analyst recommendations

The main objective of this study is to distinguish whether the forecast dispersion anomaly is due to Miller’s (J Finance 32(4):1151–1168, 1977) overpricing hypothesis or idiosyncratic risk, by conditioning the sample on “buy” and “sell” consensus recommendations. Observations on the long and short possibilities provided to the investors by the analyst stock recommendations can help us infer on the impact of short sale constraints even though they are not directly observed. This study provides strong evidence that the impact of analyst forecast dispersion is more pronounced in the group of stocks that receive the least favorable recommendations in a given period, even after controlling for the idiosyncratic risk, Fama–French factors (J Financ Econ 33(1):3–56, 1993; J Financ Econ 116(1):1–22, 2015) and even short-sale constraints. These results are consistent with Miller’s (1977) hypothesis, according to which if short-sale constraints bind, high opinion divergence stocks become overpriced and hence have low subsequent returns.     

The information content of director trading: Evidence from acquisition announcements in Australia

In response to the long-standing debate about the information content of director trading, this study investigates the implications of director stock trading before an acquisition announcement by the company. Using a sample of 1249 acquisition announcements made by Australian acquiring firms between 2003 and 2012, we find that the stocks of acquiring firms with net director sales tend to underperform those of acquiring firms with net director purchases or with no director trades. This evidence supports the notion that director trading conveys useful information about the quality of subsequent acquisitions. Further, the informational effect of net director sales is most pronounced for acquisitions where the method of payment is stock, implying that the acquiring firm's stock may be overvalued.     

Short-sale refinancing and price adjustment speed to bad news: Evidence from a quasi-natural experiment in China

Short selling may accelerate stock price adjustment to negative news. However, the literature provides mixed evidence for this prediction. Using short-sale refinancing and a staggered difference-in-differences (DID) model, this paper explores the effect of short selling on stock price adjustment. Our results show that (1) short-sale refinancing improves the speed of stock price adjustment to negative news. This result holds after we control for endogeneity. (2) The positive relationship between short-sale refinancing and stock price adjustment speed is significant in subsamples of stocks with higher earnings management or lower accuracy of analyst forecasts, indicating that firms with more opaque information are more likely to be targeted by short sellers. In subsamples of stocks with a higher ownership concentration or lower ownership by institutional investors, short selling is more likely to increase the speed of stock price adjustment, indicating that ownership structure may influence negative news mining. (3) As short-sale refinancing exacerbates the absorption of bad news by stock prices, it increases crash risk. This study enriches the research on the economic consequences of short selling and provides empirical evidence supporting regulations on short selling in China.     

Insider sales based on short-term earnings information

I find strong evidence of insiders selling shares prior to imminent bad earnings news through their Rule 10b5-1 trading plans. While Rule 10b5-1 selling plans may conjure images of regular selling over a sustained period of time, I find that insiders’ sales under these plans often consist of a small number of sales (the median plan consists of four sales) and commonly occur over a short period of time (the median plan lasts less than 150 days). Abnormal stock returns, earnings surprises, and abnormal earnings announcement returns are all significantly negative following plans that are short-term in nature, but not following plans that are long-term in nature. Although Rule 10b5-1 does not specify a minimum length for selling plans, finding that sales within short plans significantly outperform sales within longer plans suggests that restrictions on plan length would reduce the incidence and appearance of informed selling through Rule 10b5-1 plans.