SEQUELS ARE RARELY AS good as the originals, so I approach this review of the market efficiency literature with trepidation. The task is thornier than it was 20 years ago, when work on efficiency was rather new. The literature is now so large that a full review is impossible, and is not attempted here. Instead, I discuss the work that I find most interesting, and I offer my views on what we have learned from the research on market efficiency.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1540-6261.1991.tb04636.x

Efficient Capital Markets: II

We propose a theory of securities market under- and overreactions based on two well-known psychological biases: investor overconfidence about the precision of private information; and biased self-attribution, which causes asymmetric shifts in investors’ confidence as a function of their investment outcomes. We show that overconfidence implies negative long-lag autocorrelations, excess volatility, and, when managerial actions are correlated with stock mispricing, public-event-based return predictability. Biased self-attribution adds positive short-lag autocorrelations ~“momentum”!, short-run earnings “drift,” but negative correlation between future returns and long-term past stock market and accounting performance. The theory also offers several untested implications and implications for corporate financial policy. IN RECENT YEARS A BODY OF evidence on security returns has presented a sharp challenge to the traditional view that securities are rationally priced to ref lect all publicly available information. Some of the more pervasive anomalies can be classified as follows ~Appendix A cites the relevant literature!: 1. Event-based return predictability ~public-event-date average stock returns of the same sign as average subsequent long-run abnormal performance! 2. Short-term momentum ~positive short-term autocorrelation of stock returns, for individual stocks and the market as a whole!

/pdf/investor-psychology-and-security-market-under-and-108faczcym.pdf

Investor Psychology and Security Market Under- and Overreactions

We propose a theory of securities market under- and overreactions based on two well-known psychological biases: investor overconfidence about the precision of private information; and biased self-attribution, which causes asymmetric shifts in investors' confidence as a function of their investment outcomes. We show that overconfidence implies negative long-lag autocorrelations, excess volatility, and, when managerial actions are correlated with stock mispricing, public-event-based return predictability. Biased self-attribution adds positive short-lag autocorrelations (momentum), short-run earnings drift, but negative correlation between future returns and long-term past stock market and accounting performance. The theory also offers several untested implications and implications for corporate financial policy. 
Prepublication version available at https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2017

Presentation Slides for 'Investor Psychology and Security Market Under and Overreactions'

Men and Women of the Corporation

Researchers have used various measures as indications of "earnings quality" including persistence, accruals, smoothness, timeliness, loss avoidance, investor responsiveness, and external indicators such as restatements and SEC enforcement releases. For each measure, we discuss causes of variation in the measure as well as consequences. We reach no single conclusion on what earnings quality is because "quality" is contingent on the decision context. We also point out that the "quality" of earnings is a function of the firm's fundamental performance. The contribution of a firm's fundamental performance to its earnings quality is suggested as one area for future work.

/pdf/understanding-earnings-quality-a-review-of-the-proxies-their-1r9rjtuq8l.pdf

Understanding Earnings Quality: A Review of the Proxies, Their Determinants and Their Consequences

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/26147/0000224.pdf

Insiders' profits, costs of trading, and market efficiency

This paper documents that, for the period from 1975 to 1989, the aggregate net number of open market purchases and sales by corporate insiders in their own firms predicts up to 60 percent of the variation in one-year-ahead aggregate stock returns. This study also examines whether the ability of aggregate insider trading to predict future stock returns can be attributed to changes in business conditions or movements away from fundamentals. Evidence suggests that both explanations contribute to the predictive ability of aggregate insider trading.

Why Does Aggregate Insider Trading Predict Future Stock Returns

This study investigates the information content of aggregate insider trading by analyzing ap proximately sixty thousand open-market sales and purchases by insider s from January 1975 to October 1981. The paper first examines the rel ation between market movements and aggregate insider trading. The evi dence suggests that insiders cannot always distinguish between the ef fects of firm-specific and economywide factors. The paper also invest igates whether publicly-available information about aggregate insider trading activity can help predict future stock-market returns and pr ovide market analysts with market timing ability. Copyright 1988 by the University of Chicago.

The Information Content of Aggregate Insider Trading

T HIS study empirically examines the effects of increases in the level and enforcement of insider-trading regulations in the 1980s on corporate insiders.1 The main goal of the insider-trading regulations is to prevent insiders from trading on the basis of material, nonpublic corporate information. In addition, regulations require that insiders report their transactions to the Securities and Exchange Commission (SEC) and refrain from generating short-term profits by trading in their own firms' stocks. Regulations also prohibit insiders from short selling the securities of their firms.

https://www.jstor.org/stable/pdfplus/725558.pdf

The Effectiveness of the Insider-Trading Sanctions

The authors document significant sales by the insiders of firms filing bankruptcy petitions prior to the filing date. They also find that selling is more intense for top executives and officers and that insiders in general systematically sell stock before prices fall and buy stock after prices have fallen. Although this trading pattern may simply reflect an implicit compensation arrangement between insiders and stockholders, the significant sell-off does raise potential questions regarding managements' incentives to maximize shareholder wealth throughout the Chapter 11 process. Copyright 1997 by University of Chicago Press.

https://www.jstor.org/stable/10.1086/209715

H. Nejat Seyhun

Papers

Insiders' profits, costs of trading, and market efficiency

Why Does Aggregate Insider Trading Predict Future Stock Returns

The Information Content of Aggregate Insider Trading

The Effectiveness of the Insider-Trading Sanctions

Corporate Bankruptcy and Insider Trading