Abstract We study the effects of a market-wide short-sale constraint in a dynamic economy with heterogeneous beliefs. Imposing the constraint reduces the stock price if the optimistic investors' intertemporal elasticity of substitution (IES) is less than one and increases the stock price if the optimist's IES is greater than one. In calibrated examples, the optimist's market price of risk falls and the interest rate rises when the constraint binds. Imposing the constraint leads to a higher stock volatility if the optimist's IES is less than one and a lower stock volatility if the IES is greater than one.

We study insider trading in a dynamic setting. Rational, but uninformed, traders choose between investment projects with different levels of insider trading. Insider trading distorts investment toward assets with less private information. However, when investment is sufficiently information elastic, insider trading can be welfare-enhancing because of more informative prices. When insiders repeatedly receive information, they trade to reveal it when investment is information elastic because good news increases investment and hence future insider profits. Thus, more information is revealed and uninformed agents are exploited less frequently by insiders. Both effects are Pareto-improving. Finally, we consider various insider-trading regulations.

Abstract Elementary portfolio theory implies that environmentalists optimally hold more shares of polluting firms than non-environmentalists, and that polluting firms attract more investment capital than otherwise identical non-polluting firms through a hedging channel. Pigouvian taxation can reverse the aggregate investment results, but environmentalists still overweight polluters. We introduce countervailing motives for environmentalists to underweight polluters, comparing the implications when environmentalists coordinate to internalize pollution, or have nonpecuniary disutility from holding polluter stock. With nonpecuniary disutility, introducing a green derivative may dramatically alter who invests most in polluters, but has no impact on aggregate pollution.