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.     

Constraints on short-selling and asset price adjustment to private information

This paper models effects of short-sale constraints on the speed of adjustment (to private information) of security prices. Constraints eliminate some informative trades, but do not bias prices upward. Prohibiting traders from shorting reduces the adjustment speed of prices to private information, especially to bad news. Non-prohibitive costs can have the reverse effect, but this is unlikely. Implications are developed about return distributions on information announcement dates. Periods of inactive trade are shown to impart a downward bias to measured returns. An unexpected increase in the short-interest of a stock is shown to be bad news.     

Asset pricing with heterogeneous preferences,beliefs, and portfolio constraints

Portfolio constraints are widespread and have significant effects on asset prices. This paper studies the effects of constraints in a dynamic economy populated by investors with different risk aversions and beliefs about the rate of economic growth. The paper provides a comparison of various constraints and conditions under which these constraints help match certain empirical facts about asset prices. Under these conditions, borrowing and short-sale constraints decrease stock return volatilities, whereas limited stock market participation constraints amplify them. Moreover, borrowing constraints generate spikes in interest rates and volatilities and have stronger effects on asset prices than short-sale constraints.     

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.     

Short-horizon incentives and stock price inflation

Do managerial incentive horizons have capital market consequences? We find that they do when short-sale constraints are more binding. Firms experience significant stock price inflation when their CEOs have short horizon incentives. The short-horizon CEOs sell more shares at inflated prices and generate greater abnormal trading profits. The stock price inflation is partly explained by greater earnings surprises and more positive investor reaction to the surprises. To inflate stock prices, short-horizon firms are more likely to employ income-increasing discretionary accruals. Consistent with theoretical predictions, all these effects are attenuated or statistically insignificant when short-sale constraints are less binding.     

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).     

Derivatives traders’ reaction to mispricing in the underlying equity

This article examines trading behavior in the options market conditioned on mispricing in the underlying stock. We investigate the price equilibrium between the observed equity asset and the options-implied synthetic share as well as the relative divergence between the two prices. We find a consistently positive relation between the level of stock mispricing and violations of the upper-boundary condition using derivatives, along with an increase in price divergence. To control for the effect of shorting limitations on mispricing, we further examine prices during the short-sale ban in 2008. The results hold and in many instances are more significant during the ban period. Given the persistent disequilibria between the synthetic and observed stock prices, we argue the results are evidence of informed trading in the derivatives market.     

Shorting flows,public disclosure,and market efficiency

Shorting flows remain a significant predictor of negative future stock returns during 2010–2015, when daily short-sale volume data are published in real time. This predictability decays slowly and lasts for a year. Long-term shorting flows are more informative than short-term shorting flows. Indeed, abnormal short-term shorting flows do not predict future returns or anticipate bad news. We find that short sellers exploit prominent anomalies. A comparison with the Regulation SHO data indicates that the predictability is much shorter-term during 2005–2007. Short sellers appear to have shifted from trading on short-term private information to trading on long-term public information that is gradually incorporated into prices.     

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.     

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.     

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.     

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.     

Analyst coverage and the idiosyncratic skewness effect in the Taiwan stock market

In this study, we investigate the effect of analyst coverage on the idiosyncratic skewness (IS) anomaly. We adopt the ordinary least square method with the corresponding standard errors that are heteroskedasticity consistent and clustered by firm. Our results show that the IS anomaly exists in the Taiwanese stock market, and analyst coverage mitigates it. Moreover, we use one exogenous shock on analysts due to the mergers and closures of brokerages to address the endogenous concern, and to confirm that analyst coverage reduces the IS anomaly. Specifically, the buy and upgrade recommendations of analysts mitigate the negative IS spreads, but their sell and downgrade recommendations aggravate those spreads. Further, we use a quasi-natural experiment on short-sale constraints in the Taiwanese stock market and find that the effects of analysts' recommendations on the negative IS spreads are not subsumed by those constraints.     

Which Shorts Are Informed?

We construct a long daily panel of short sales using proprietary NYSE order data. From 2000 to 2004, shorting accounts for more than 12.9% of NYSE volume, suggesting that shorting constraints are not widespread. As a group, these short sellers are well informed. Heavily shorted stocks underperform lightly shorted stocks by a risk‐adjusted average of 1.16% over the following 20 trading days (15.6% annualized). Institutional nonprogram short sales are the most informative; stocks heavily shorted by institutions underperform by 1.43% the next month (19.6% annualized). The results indicate that, on average, short sellers are important contributors to efficient stock prices.     

Dispersion in beliefs among active mutual funds and the cross-section of stock returns

We propose a measure of dispersion in fund managers? beliefs about future stock returns based on their active holdings, i.e., deviations from benchmarks. We find that both the level of and the change in dispersion positively predict subsequent stock returns on a risk-adjusted basis. This effect is particularly pronounced among stocks with high information asymmetry and binding short-sale constraints. These results suggest that a subgroup of informed managers drives up the dispersion in active holdings when they place large bets after receiving positive private information. Binding short-sale constraints, however, prevent them from fully using their negative private information, leading to low dispersion in active holdings.     

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.     

Short-sale constraints: Reductions in costs of capital or overvaluation? Evidence from Hong Kong

We examine the effects of short-sale constraints in Hong Kong where stocks can be shorted only if they are included on an official short-sale list. Using revisions to the list, we test two hypotheses — 1) that short-sale constraints lead to overvaluation and 2) that they lead to lower costs of capital. We find weak support for the Diamond and Verrecchia (1987) version of the overvaluation hypothesis, but more compelling evidence supporting the Xu (2007) version of the overvaluation hypothesis and the cost of capital hypothesis. We argue that in the context of our tests the Xu overvaluation hypothesis is actually a reformulation of the cost of capital hypothesis and that the bulk of our evidence, therefore, supports the notion that short-sale constraints reduce capital costs.     

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.     

Short-selling bans and institutional investors' herding behaviour: Evidence from the global financial crisis

The literature on short-selling restrictions focusses mainly on a ban's impact on market efficiency, liquidity and overpricing. Surprisingly, little is known about the effects of short-sale constraints on herd behaviour. Since institutional investors have come to dominate mature stock markets and rely extensively on short sales, constraining these traders may influence the asset pricing process. We investigate six stock markets that faced bans during the recent global financial crisis. Our empirical evidence shows that short-selling restrictions exhibit either no influence on herding formation or induce adverse herding. This implies a higher dispersion of returns around the market compared to rational asset pricing, which can be interpreted as an increase in uncertainty among stock market investors.     

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.