We develop a theory of market crashes based on differences of opinion among investors. Because of short-sales constraints, bearish investors do not initially participate in the market and their information is not revealed in prices. However, if other previously bullish investors bail out of the market, the originally bearish group may become the marginal "support buyers," and more will be learned about their signals. Thus accumulated hidden information comes out during market declines. The model explains a variety of stylized facts about crashes and also makes a distinctive new prediction—that returns will be more negatively skewed conditional on high trading volume.

Managements (“insiders”) of many corporations, especially small or newly-public firms, invest considerable resources in investor relations. We develop a model to explore the incentives of insiders to undertake such costly investments. We point out that insiders may undertake such investments not necessarily to improve the share price, but to enhance the liquidity of their block of shares. This leads to a divergence of interest between insiders and dispersed outside shareholders regarding investor relations. Our model predicts that the demographics of insiders (e.g. liquidity needs, size of equity stakes) are important determinants of the extent of investor relations across firms.

We model a market populated by two groups of boundedly rational agents: “newswatchers” and “momentum traders.” Each newswatcher observes some private information, but fails to extract other newswatchers' information from prices. If information diffuses gradually across the population, prices underreact in the short run. The underreaction means that the momentum traders can profit by trend‐chasing. However, if they can only implement simple (i.e., univariate) strategies, their attempts at arbitrage must inevitably lead to overreaction at long horizons. In addition to providing a unified account of under‐ and overreactions, the model generates several other distinctive implications.

The Russell 1000 and 2000 stock indexes comprise the first 1000 and next 2000 largest firms ranked by market capitalization. Small changes in the capitalizations of firms ranked near 1000 move them between these indexes. Because the indexes are value-weighted, more money tracks the largest stocks in the Russell 2000 than the smallest in the Russell 1000. Using this discontinuity, we find that additions to the Russell 2000 result in price increases and deletions result in price declines. We then identify time trends in indexing effects and the types of funds that provide liquidity to indexers.

We infer the latent social networks of investors using data on their stock holdings. We map linkages to portfolio weights using a portfolio-choice model. The precision of an investor’s private signal about firm value is assumed to increase with his connections in the city where the firm is headquartered. Using money-manager data, we find that managerial linkages to a city are overly dispersed relative to the Erdös–Rényi model of i.i.d. connections. Managers at the tail of this distribution with non-i.i.d. linkages have more university alumni in that city. Their stock holdings there outperform their holdings in other cities.

Motivated by the recent subprime mortgage crisis, we explore whether speculative bubble models of equity based on investor disagreement and short-sales constraints can also provide an explanation for the overvaluation of debt contracts. We find that this is unlikely. Equity bubbles are loud: price and volume go together as investors speculate on capital gains from reselling to more optimistic investors. But this resale option is limited for debt since its upside payoff is bounded. Debt bubbles then require an optimism bias among investors. But greater optimism leads to less speculative trading as investors view the debt as safe and having limited upside. Debt bubbles are hence quiet—high price comes with low volume. We find the predicted price–volume relationship of credits over the 2003–2007 credit boom.

This paper develops an equilibrium model of a competitive futures market in which investors trade to hedge positions and to speculate on their private information. Equilibrium return and trading patterns are examined. (1) In markets where the information asymmetry among investors is small, the return volatility of a futures contract decreases with time‐to‐maturity (i.e., the Samuelson effect holds). (2) However, in markets where the information asymmetry among investors is large, the Samuelson effect need not hold. (3) Additionally, the model generates rich time‐to‐maturity patterns in open interest and spot price volatility that are consistent with empirical findings.

We develop a theory of market crashes based on differences of opinion among investors. Because of short-sales constraints, bearish investors do not initially participate in the market and their information is not revealed in prices. However, if other previously bullish investors bail out of the market, the originally bearish group may become the marginal “support buyers,” and more will be learned about their signals. Thus accumulated hidden information comes out during market declines. The model explains a variety of stylized facts about crashes and also makes a distinctive new prediction—that returns will be more negatively skewed conditional on high trading volume.

There is mixed evidence on whether the marginal dollar spent on corporate social responsibility is due to agency problems. We propose an approach by modeling how the 2003 dividend tax cut, which increased after-tax insider ownership and better aligned managerial and shareholder interests, affected the marginal dollar spent on firm responsibility. We confirm key predictions of our agency model: following the tax cut, moderate insider-ownership firms experience larger declines in their responsibility ratings and increases in their valuations relative to other firms. We also confirm another implication regarding managerial misalignment using a regression-discontinuity design of close votes on shareholder-governance proposals. (JEL G30, G31, G35) Authors have furnished an Internet Appendix, which is available on the Oxford University Press Web site next to the link to the final published paper online.