Short Selling Research Articles

How Informed Are International Short Sellers? Global and Local Industry Concentration of Short Sellers

How Informed Are International Short Sellers? Global and Local Industry Concentration of Short Sellers

Polytope Fraud Theory

Polytope Fraud Theory (PFT) extends the existing triangle and diamond theories of accounting fraud with ten abnormal financial practice alarms that a fraudulent firm might trigger. These warning signals are identified through evaluation of the shorting behavior of sophisticated activist short sellers, which are used to train several supervised machine learning methods in detecting financial statement fraud using published accounting data. Our contributions include a systematic manual collection and labeling of companies that are shorted by professional activist short sellers. We also combine well-known asset pricing factors with accounting red flags in financial features selections. Using 80 % of the data for training and the remaining 20 % for out-of-sample test and performance assessment, we find that the best method is XGBoost, with a Recall of 72 % and F1-score of 82 %. Other methods have relatively lower performance, demonstrating the robustness of our results. This shows that the sophisticated activist short sellers, from whom the algorithms are learning, have excellent accounting insights, tremendous forensic analytical knowledge, and sharp business acumen. Our feature importance analysis indicates that potential short-selling targets share many similar financial characteristics, such as bankruptcy or financial distress risk, clustering in some industries, inconsistency of profitability, high accrual, and unreasonable business operations. Our results imply the possible automation of advanced financial statement analysis, which can both improve auditing processes and effectively enhance investment performance. Finally, we propose the Unified Investor Protection Framework, summarizing and categorizing investor-protection related theories from the macro-level to the micro-level.

The Signalling Effect of Corporate Social Responsibility Reporting: Evidence From Short Selling

Using exogenous regulatory changes that have gradually removed short‐sale restrictions in China's stock exchanges, we examine how such deregulation influences firms’ corporate social responsibility (CSR) reporting. Our findings indicate a significant improvement in the calibre of CSR reporting among firms designated as qualified for short selling in a deregulation pilot program (pilot firms) compared to non‐pilot firms. Moreover, our empirical evidence shows that the improvement in CSR reporting practices is greater for pilot firms experiencing stronger downward price pressure, negative earning news, higher bankruptcy risk, greater ownership concentration, and those classified as state‐owned enterprises. These results demonstrate that firms susceptible to price declines from short selling utilize CSR reporting as a visible and credible signal to safeguard and enhance corporate reputation, garnering increased stakeholder support.

Short Selling Threat and News Sentiment Management in Press Releases

This study presents evidence that firms actively manage sentiment in press releases to reduce their exposure to short selling threats. I exploit the suspension of short selling constraints as an exogenous shock to the short selling threat borne by firms. Using a sample of 110,938 firm-press release observations from 2001 to 2007 and a difference-in-differences methodology, I find that firms facing increased short selling threats increase the sentiment in press releases after the suspension of short selling constraints more than otherwise similar firms without increased short selling threats. Meanwhile, higher sentiment in corporate press releases deters short sellers. Specifically, stocks with the suspension of short selling constraints are more likely to be short sold but such stocks with higher news sentiments are less likely to be short sold. These findings suggest that press release sentiment can be strategically used by firms to advance their own interests.

A study of the impact of short selling mechanism on the stock price collapse risk

Drawing from an extensive review of existing literature, this study investigates the influence of the short selling mechanism (SSM) on x through both theoretical and empirical lenses. It further assesses whether this mechanism can effectively mitigate stock price collapse risk (SPCR). The findings reveal that the SSM has a significant moderating effect on stock price declines, with stability tests for alternative factors affirming the robustness of these results. The study then narrows its focus to listed companies in China, examining the role of the SSM in this specific context. Results indicate that the SSM enhances the information content of stocks, thereby reducing the risk of stock market crashes. Using regression analysis and a mediating role model, the paper empirically explores the relationship between the SSM and SPCR. The conclusions suggest that the SSM can partially reduce the risk of stock market crashes by increasing the information content of stock prices.

Can Bitcoin trigger speculative pressures on the US Dollar? A novel ARIMA-EGARCH-Wavelet Neural Networks

In recent years, Bitcoin has garnered attention as a digital currency, prompting increasing debate regarding its effects on traditional financial markets, particularly the US dollar. This study investigates the relationship between Bitcoin and the US dollar, especially in the contexts of speculative attacks, where investors attempt to devalue a currency, and short squeezes, where rapid price rises force short sellers to quickly buy back assets to avoid further losses. The study employs a novel hybrid model combining an autoregressive moving average, Generalized Autoregressive Conditional Heteroskedasticity, and Wavelet Neural Networks techniques with neural networks approaches. The results suggest that significant trading activity in Bitcoin/US dollar, particularly during speculative attacks and short squeezes, can substantially impact the US dollar/EUR market, increasing price volatility as traders adjust their strategies. These adjustments, along with risk management strategies, drive higher trading volumes and further volatility. Our findings demonstrate that our novel hybrid model combined with Quantum Recurrent Neural Networks provides the most accurate predictions, offering valuable insights to inform trading strategies in both Bitcoin/US dollar and US dollar/EUR markets. This study has important implications for policymakers and market participants, emphasising the need to understand the relationship between Bitcoin and the US dollar for financial stability and effective policy formulation. It also highlights the necessity of advanced modeling techniques to accurately predict cryptocurrency market behavior.

Heterogeneous beliefs and short selling taxes: A note

Short selling is widespread in financial markets but regulators can ban short positions. The intermediate policy of taxing short sellers has been studied in an asset pricing model with evolutionary competition of two belief types (Anufriev and Tuinstra, 2013). We extend this approach to an arbitrary number of belief types H, giving 3H−2H cases to check each period in the worst-case scenario. We provide analytic expressions for asset prices along with conditions on beliefs (optimism) that determine which types take long, short or zero asset positions at the market-clearing price. We use these results to construct a fast solution algorithm (quadratic in H) which can solve models with hundreds or thousands of types in a matter of seconds. A numerical example with a short-selling tax and many heterogeneous beliefs in evolutionary competition shows that price dynamics can differ substantially relative to the benchmark of few types.

Negative Externalities of Regulation: Identity‐relevant Information in Mandatory Short‐selling Disclosures

Since November 2012, short sellers have been required to disclose all their significant short positions against European firms. While this regulation was primarily implemented to have implications for financial markets, I explore its negative externalities on shorted firms. Using mandatory disclosures of short positions between 2013 and 2019, I find that short‐selling notifications and the number of short sellers with an open short position are positively associated with shorted firms’ dividend policies. Notably, the association is more pronounced for upward and initial notifications compared to downward and follow‐up notifications. These results are robust to several matching methods and a battery of robustness tests. Additional results reveal that shorted firms might increase their dividends because short‐selling disclosures reveal the identity of active and large short sellers, highlighting the importance of short sellers’ heterogeneity. I also show that shorted firms increase their dividends temporarily and do not react homogenously, as they engage in a cost–benefit analysis to decide whether to use their dividend policy. Overall, I document the real effects on shorted firms of an alternative form of short selling, bridging the gap between passive and activist short selling. I conclude that mandatory short‐selling disclosure regimes carry negative externalities for firms due to the provision of short sellers’ identity‐relevant information.

Short selling and firms’ long-term stock return volatility: Evidence from Chinese concept stocks in Hong Kong

This paper examines the impact of short selling on the long-term volatility of firms' stock returns, highlighting the moderating effect of corporate governance quality. We analyze a sample of Chinese concept stocks listed in Hong Kong from 2015 to 2023, separating stock volatility into short- and long-term components with a GARCH-MIDAS model and differentiating between noisy and informed short selling. We provide evidence through portfolio and regression analyses that short selling increases stock return volatility, with the most significant impact observed in the long-term component, fueled in part by noisy short selling. However, this effect can be mitigated by managers who invest in improving their firms’ corporate governance quality. Implications of our findings for both research and practical applications are discussed.

Broker and institutional investor short selling

Broker and institutional investor short selling

Mapping the evolution of ethical standards in trading: A bibliometric analysis

Amid concerns about financial social responsibility, the significance of ethical standards in trading has grown. Recent years have seen increased focus on exploring diverse ethics in trading, from fundamental principles to cutting-edge techniques. Our objective is to shed light on the state of ethics in trading through a comprehensive bibliometric analysis of 3010 research articles published between 1976 and 2022, drawing data from the Web of Science Core Collection (WoS). This analysis includes identifying publications, examining co-authorship patterns, determining top countries in scientific output, analyzing citations, exploring influential journals, and assessing keyword co-occurrence. Recurring themes mirror the academic progression of ethics in trading, especially regarding new technologies like high-frequency trading, offering insights for future research. Two standout considerations are the ethical implications of short selling in high-frequency trading and ethical management in commodity trading, linked to the evolving landscape of social responsibility in trade management.

Does Short Selling Regulate Insider Trading?

This study investigates the impact of short selling on the relationship between the insider net buying ratio and excess returns, as well as on insider selling volume. The research period is divided into three distinct phases: short selling allowed, short selling banned, and partial short selling. The two primary findings of the analysis are as follows. First, the profitability of insider trading, assessed through the relationship between the insider net buying ratio and excess returns, is impacted positively when short selling is banned and negatively when it is permitted. Second, the insider selling volume significantly increases following short selling bans and decreases when the same is allowed. These results suggest that short sellers function as a market discipline mechanism, regulating both the profitability and volume of insider trading. This indicates that short selling regulations wield a substantial influence on the behavior and profitability of insider trading.

Mispricing and Anomalies: An Exogenous Shock to Short Selling from JGTRRA

We investigate the causal impact of short-sale constraints on market anomalies by analyzing a comprehensive set of 182 anomalies. Our approach leverages a persistent, robust, and plausibly exogenous shock to short-selling supply caused by the dividend tax law change in the Job and Growth Tax Relief Reconciliation Act (JGTRRA) of 2003. Our findings reveal that anomalies decline after JGTRRA. However, this tax law change impedes arbitrageurs’ ability to correct mispricing, resulting in anomalies decaying less following dividend record months compared to other months post-JGTRRA. Furthermore, this effect is concentrated on overpriced stocks as opposed to underpriced stocks. Interestingly, while this shock significantly affects most types of anomalies, valuation anomalies remain unaffected.

Hindenburg Research and the business of short selling

Hindenburg Research and the business of short selling

Pairs trading with costly short-selling

We study an optimal pairs trading model with costly short-selling. When the investor has logarithm utility function, we derive the solution in closed form, which shows that: the optimal allocation functions are piece-wise linear in the pair's relative price; stock borrowing fees asymmetrically reduce the optimal size of the long/short position; and for risk-hedging purpose, it can be optimal to short sell even when the stock borrowing fees outweigh the expected return earned from short selling. When the investor has power utility function, we propose analytical allocation functions adopting which only causes a small utility loss. When the investor is constrained from borrowing funds, the margin requirement for short selling can significantly affect the trading strategy. Empirically, we demonstrate the importance of incorporating short selling costs when trading pairs in China's stock market and verify the model-implied relation between short selling costs and profitability of pairs trading.

Optimists, Pessimists, and Stock Prices

We review the academic findings from psychology and economics on disagreement—specifically, the effect of disagreement on asset prices. We discuss measurement of disagreement and how disagreement, coupled with constraints on short selling, can sideline pessimistic investors and result in overpricing. We review the literature on short selling in financial markets, paying particular attention to how and why some issues become hard-to-borrow and what factors go into the determination of borrowing costs, and we discuss the evolution of borrowing costs over the last several decades. We show how an examination of the prices and borrowing costs for constrained stocks can lead to an improved understanding of how disagreement in financial markets arises and is resolved, and we discuss directions for future research.

Do short sellers amplify extreme market declines?

When the market falls sharply, short sellers are criticized for intensifying price declines by manipulative trading that pushes prices below fundamental values. Contrary to this view, we find that increases in institutional and retail short seller's trading on the days of marketwide declines are associated with overpriced stocks. Their trading is economically profitable: a portfolio that buys the least shorted and sells short the most shorted stocks by institutional (retail) investors earns 0.90% (0.79%) risk-adjusted weekly returns. Overall, institutional and retail short sellers adopt valuation-based trading during market-wide declines.

Agreeing to disagree: Informativeness of sentiments in internet message boards

We study the informativeness of the sentiment of posts on Australia's largest online stock message board, HotCopper. We explore whether disagreements among sentiment form a signal about the fundamental news of a company. We find that positive sentiment is associated with noise induced (uniformed) trading whereas negative sentiment contains value-relevant information about a firm's performance. Our empirical findings suggest that short selling activity reduces overreactions of abnormal returns in a noisy environment on the same day. Furthermore, we observe a sentiment convergence pattern around annual earnings announcements and low levels of sentiment homogeneity relate to significantly lower annual earnings surprise. This supports the view that disagreements among sentiments are a signal of bad news about firm fundamentals.

The Predictive Ability and Profitability of Moving Average Rules in the Saudi Stock Market

Abstract Following the implementation of capital market reforms, Saudi Arabia has opened up its stock market to international investors. This liberalisation has led to the inclusion of the stock exchange into leading global indices, which is expected to lead to an influx of foreign investment. Thus, it is important and timely to examine the efficiency of the Saudi stock market. To that end, this paper conducts a comprehensive investigation of the predictive ability and profitability of a popular trading rule, the moving average rule, using firm-level data for the Saudi stock market over the period 1st January 2008 to 31st December 2017. The results show that the moving average rule has predictive ability; the active rules for a majority of the sample companies outperformed the corresponding passive strategy. Furthermore, the results were economically significant as the rules were profitable even after the consideration of transaction costs. The results also showed that the most profitable moving average rules were those with short-moving average lengths, and that the introduction of a bandwidth, which serves to eliminate weak trading signals, had a positive impact on rule profitability. Importantly, the analysis showed that the most profitable component of the rule related to short selling as these trades resulted in higher profits than the long positions. A disaggregated analysis of sectors showed that the trading rules outperformed the buy-and-hold strategy in all seven industries considered, while the analysis of covariance revealed the importance of careful selection of filter size. Overall, the analysis documents significant inefficiencies in the Saudi stock market and suggests that the employment of a simple trading rule, based on past price data, can yield substantial profits across companies and sectors even in a costly trading environment. These findings suggest that the recent reforms that were implemented to improve the efficiency of the Saudi stock market have been suboptimal, and that further regulatory reform is required.

Overconfidence, short selling, and corporate fraud: Evidence from China

Using data on Chinese A-share listed firms from 2010 to 2020, this study employs a partial observable bivariate probit model and introduces fraud triangle theory to explain the mechanisms of overconfidence, short selling, and corporate fraud. Our findings show that overconfidence offers rationalization to investors and corporations, reduces fraud detection, and increases corporate incentives to commit fraud. Short selling promotes information transparency, increases fraud detection, and reduces the opportunities to commit fraud. Moreover, it moderates the relationship between overconfidence and corporate fraud. In addition, overconfidence and short selling affect different types of fraud (operational, executive, and information disclosure fraud). Furthermore, our results show heterogeneity among the ownership types. This study provides a theoretical basis for corporate fraud governance in China’s stock market.