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.     

Role of Speculative Short Sales in Price Formation: The Case of the Weekend Effect

We argue that short sellers affect prices in a significant and systematic manner. In particular, we contend that speculative short sales contribute to the weekend effect: The inability to trade over the weekend is likely to cause these short sellers to close their speculative positions on Fridays and reestablish new short positions on Mondays causing stock prices to rise on Fridays and fall on Mondays. We find evidence in support of this hypothesis based on a comparison of high short-interest stocks and low short-interest stocks, stocks with and without actively traded options, IPOs, zero short-interest stocks, and highly volatile stocks.     

The Weekend Effect, 'Reverse' Weekend Effect, and Firm Size

In this paper, we find a 'reverse%rsquo; weekend effect — whereby returns for Monday are positive and significantly greater than returns for the preceding Friday — in recent data for major stock indexes. We also find that, while a weak weekend effect exists in portfolios of smaller firms, the effect begins to diminish and weak 'reverse' weekend effect begins to appear in medium size firms. The 'reverse' weekend effect becomes strong and statistically significant in portfolios of large firms. The detection of a 'reverse' weekend effect in portfolios of large firms is a new finding in the literature.     

The determinants of short selling: evidence from the Hong Kong equity market

While most financial regulators agree that short sellers have an important role to play in ensuring an efficiently functioning market, it is interesting to note that many did not hesitate to ban short selling during the recent financial crisis. This apparent contradiction most likely stems from a lack of understanding about what motivates short trading. In this paper, we focus on the determinants of short selling during ‘normal’ trading in the Hong Kong stock market. We find that dividend payments, company fundamentals, risk, option trading, the interest rate spread and past returns and short selling are all significant determinants of short selling.     

The curious case of converts

We document negative abnormal returns and abnormally high short selling in the trading days immediately before the private placements of U.S. convertible bonds. Issues experiencing greater post-placement short selling have more intense pre-placement short selling. In contrast, there are no pre-placement negative abnormal returns and less pre-placement abnormal short selling for issuers who also engage in share repurchases. Pre-placement findings are related to specific terms of the converts and related buybacks. While other potential explanations exist, the overall weight of the evidence suggests that the most plausible explanation is front-running.     

Informed short sales and option introductions

This study examines how the introduction of options affects the level of informed short selling. In particular, we test whether option introductions increases or decreases the level of informed short selling. Our tests are motivated by a theoretical debate in the literature. The first stream of literature argues that introducing options into markets may increase speculative trading which can result in less informed trading when informed traders perceive speculative trades as noise. The second stream argues that introducing options into markets improves the informational environment of the market because option prices provide an additional information mechanism for informed traders. We approximate informed short selling by examining (i) non-exempt short sales, (ii) contrarian short-selling activity, and (iii) the return predictability contained in shorting activity. Results show that non-exempt shorting activity increases after options become available. Further, we show that both the level of contrarian short selling and the return predictability contained in short selling increase after options are listed. Our results suggest that informed short selling increases after options are introduced.     

Weekend Effect, 'Reverse' Weekend Effect, and Investor Trading Activities

Abstract:   In this study, we document evidence of a 'reverse' weekend effect – whereby Monday returns are significantly positive and they are higher than the returns on other days of the week – over an extended period of eleven years (from 1988 to 1998). We also find that the 'traditional' weekend effect and the 'reverse' effect are related to firm size in that the 'traditional' weekend effect tends to be associated with small firms while the 'reverse' weekend effect tends to be associated with large firms. In addition, we find that during the period in which the 'reverse' weekend effect is observed, Monday returns for large firms tend to follow previous Friday returns when previous Friday returns are positive , but they do not follow the previous Friday returns when Friday returns are negative . Furthermore, we find that during the period in which the 'reverse' weekend effect is observed, Monday returns are positively related to the volume of medium‐size and block transactions, but negatively related to the volume of odd‐lot transactions.     

Day-of-the-week and intraday effects in stock returns

This study examines day-of-the-week effects using hourly values of the Dow Jones Industrial Average. We find that over the 1963–1983 period the weekend effect has sifted from characterizing active trading on Monday to characterizing the non-trading weekend. Over the early part of our sample period negative returns characterize each hour of trading on Monday, while the return from Friday close to Monday open is positive. In the most recent subperiod, Monday average hourly returns after noon are all positive and the weekend effect is due to negative average returns from Friday close to Monday open.     

Arbitrage vs. informed short selling: Evidence from convertible bond issuers

Prior literature examines the effect of either informed or arbitrage short selling on equity markets. We test the relative importance of informed and uninformed short selling around convertible bond issues and earnings announcements for the same firms over the same time period. Convertible arbitrage short selling is associated with temporary price pressure, consistent with downward sloping demand curves. Earnings announcement short selling is consistent with informed traders who anticipate future returns. Firm-specific characteristics related to the cost of short selling similarly affect both informed and arbitrage short selling. Deal-specific characteristics capturing hedging demand also strongly determine convertible arbitrage short selling.     

Why do firm fundamentals predict returns? Evidence from short selling activity

This study uses short selling activity to test whether the relation between fundamentals and future returns is due to rational pricing or mispricing. We find that short sellers target firms with fundamental performance below market expectations. We also show that short selling activity reduces the return predictability of fundamentals by speeding up the price adjustments to negative fundamental signals. To further investigate whether the returns earned by short sellers reflect rational risk premia or mispricing, we exploit a natural experiment, namely Regulation of SHO, which creates exogenous shocks to short selling by temporarily relaxing short-sale constraints. Evidence from the experiment confirms that the superior returns to short sellers result from exploiting overpricing. Overall, our study suggests that the return predictability of fundamentals reflects mispricing rather than rational risk premia.     

Does short selling improve stock price efficiency and liquidity? Evidence from a natural experiment in China

China introduced short selling for designated stocks in March 2010. Using this important policy change as a natural experiment, we examine the effect of short selling on stock price efficiency and liquidity. We show that the introduction of short selling significantly improves price efficiency, as measured by the differences in individual stock responses to market returns and the delay in price adjustments. Short selling also enhances stock liquidity, as measured by bid-ask spread and Amihud [2002. ‘Illiquidity and Stock Returns: Cross-section and Time-series Effects.’ Journal of Financial Markets 5: 31–56] illiquidity measure; and reduces stock volatility. Overall, our results suggest that short selling helps to stabilize asset prices, provides additional liquidity and improves market quality, even in an emerging economy with a less developed stock market than that in the US and Europe.     

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.     

Daily short interest,idiosyncratic risk,and stock returns

This paper examines the relation between short selling and returns and the impact of arbitrage costs on short sellers’ behavior. Using daily UK short selling data, we find that stocks with low short interest levels experience significant positive returns on both an equal- and value-weighted basis. Economic theory predicts that short sellers avoid establishing positions in stocks with high idiosyncratic risk. Our results indicate a negative relation between short interest and returns among high idiosyncratic risk stocks and that short selling activity is mostly concentrated in low idiosyncratic risk stocks where it is less costly to arbitrage fundamental risk.     

中国式卖空机制与高管减持——基于融资融券分步扩容的准自然实验

本文以我国的融资融券制度为背景,结合双重差分模型,研究卖空机制对上市公司高管减持行为的影响。研究发现,相对于非融券标的,可融券标的公司高管的月减持比例在允许卖空后下降22%,这种抑制作用在小规模、高盈余平滑度以及非国有公司中体现得更为明显。其次,成为可融券标的后,股价定价效率提高,高管减持收益显著下降。进一步地,本文将高管的减持行为分为定期性与投机性两类,发现卖空机制显著抑制了高管基于信息优势和股价偏差的投机性减持行为。     

Speculative trading preferences of retail investor birth cohorts

This study examines the effect of investor birth cohorts on speculative investment preferences. Using retail trading and portfolio data from Finland over two decades, we find that individuals who have experienced desirable macro-economic and social conditions during adolescence, such as high gross domestic product (GDP) growth and low divorce rates, are more likely to invest in speculative stocks. A positive relation is found between the proportion of speculative-prone cohorts in the stock market and returns of stocks of lottery nature. We provide new evidence on the adverse effect of speculative investments, finding that cohorts with higher speculative investment weights on their portfolios achieve lower absolute and risk-adjusted returns. We also provide support for earlier research that identifies a positive association between recent portfolio performance and the propensity to invest in speculative stocks.     

Worldwide short selling regulations and IPO underpricing

We study the impact of country-level short selling constraints on IPO underpricing. Examining 17,151 IPOs from 36 countries, we find that IPO underpricing tends to be greater in countries that ban short selling or security lending and in countries where short selling is not practiced. Non-positive first-day returns are more common in countries where short selling is allowed, security lending is allowed, and short selling is commonly practiced. Short selling constraints exacerbate the positive relation between investor sentiment and underpricing. Additional evidence suggests that higher quality information environments may partially alleviate the effects of short sale constraints on underpricing.     

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.     

The “reverse” weekend effect: the U.S. market versus international markets

In this paper we find that the “reverse” weekend effect—where average Monday returns tend to be positive—is a unique feature of the U.S. market. During the time the U.S. market exhibits the reverse weekend effect, foreign markets still show the “traditional” weekend effect or no effect at all. The results persist even after we sort the data by week of the month and month of the year. We also find that in foreign markets negative Monday returns tend to follow negative Friday returns. However, in the U.S. market, positive Monday returns tend to follow positive Friday returns.     

Can Investors Profit from the Prophets? Security Analyst Recommendations and Stock Returns

We document that purchasing (selling short) stocks with the most (least) favorable consensus recommendations, in conjunction with daily portfolio rebalancing and a timely response to recommendation changes, yield annual abnormal gross returns greater than four percent. Less frequent portfolio rebalancing or a delay in reacting to recommendation changes diminishes these returns; however, they remain significant for the least favorably rated stocks. We also show that high trading levels are required to capture the excess returns generated by the strategies analyzed, entailing substantial transactions costs and leading to abnormal net returns for these strategies that are not reliably greater than zero.     

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.