Privately informed about firm fundamentals, corporate insiders detect activism-motivated trades better than other traders. This article solves the model of this novel form of insider trading motivated by noninsider information and presents empirical evidence. Corporate insiders preserve their ownership (restraining from selling or buying more) before activist interventions go public to benefit from price appreciation and to defend their private benefits of control. Surveillance technology facilitates response to predisclosure activist trading, especially when positive information about firm fundamentals is absent, supporting the mechanism that insiders attribute order flows to activist interest when speculation on fundamentals can be ruled out.

Using high-frequency disagreement data from the investor social network StockTwits, we find that greater unsophisticated disagreement facilitates informed buying and selling. During periods of overvaluation, the facilitating effect of disagreement on trading is dampened for informed buyers but is amplified for informed sellers. These findings are unexplained by sentiment, news, and retail order flow, and they remain when we measure disagreement overnight and disagreement of technical investors, which alleviates the concern that disagreement and informed trading respond to a common shock. These findings suggest that informed traders respond meaningfully but differently to valuation changes induced by unsophisticated disagreement.

Previous research shows that incentives to meet short-term earnings targets can cause firms to increase share buybacks, leading to cuts in investments and employment. Using plant-level census data, we find that incentives to engage in earnings-per-share-motivated buybacks result in lower productivity at both the plant and firm level. We attribute this productivity drop to two mechanisms: reduced investment in productivity-augmenting technology, and inefficient allocation of resources across a firm’s plants. We identify multiple frictions—including labor unions, financial constraints, agency problems, and adjustment costs—that can constrain efficient reallocations across plants and thus exacerbate the consequences of firms’ short-term incentives.