[This article shows that introducing derivative assets increases incentives to collect information about asset payoffs. The increase in information collection makes the price of the underlying asset more informative and causes the expected price to increase. Extending the model to a dynamic setting with multiple risky assets, we find that introducing derivative assets for one asset increases the expected prices of positively correlated assets and reduces price reaction to future earnings announcements. These findings are consistent with the bulk of the empirical evidence on the relationship between the introduction of derivative assets and the behavior of asset prices.]

[Analysis of absence of arbitrage normally ignores payoffs in states to which the agent assigns zero probability. We extend the fundamental theorem of asset pricing to the case of "no empty promises" in which the agent cannot promise arbitrarily large payments in some states. There is a superpositive pricing rule that can assign positive price to claims in zero probability states important to the market as well as assigning positive prices to claims in the states of positive probability. With continuous information arrival, no empty promises can be enforced by shutting down the agent's subsequent investments once wealth hits zero.]

This article shows that introducing derivative assets increases incentives to collect information about asset payoffs. The increase in information collection makes the price of the underlying asset more informative and causes the expected price to increase. Extending the model to a dynamic setting with multiple risky assets, we find the introducing derivative assets for one asset increases the expected prices of positively correlated assets and reduces price reaction to future earnings announcements. These findings are consistent with the bulk of the empirical evidence on the relationship between the introduction of derivative assets and the behavior of asset prices.

[Portfolio turnpike theorems show that if preferences at large wealth levels are similar to power utility, then the investment strategy converges to the power utility strategy as the horizon increases. We state and prove two simple and general portfolio turnpike theorems. Unlike existing literature, our main result does not assume independence of returns and depends only on discounting of future cash flows. We also provide a critique of portfolio turnpike results, based on the observations that (1) the time required for convergence is often too large to be relevant, and (2) there is no convergence for consumption withdrawal problems.]

Analysis of absence of arbitrage normally ignores payoffs in states to which the agent assigns zero probability. We extend the fundamental theorem of asset pricing to the case of “no empty promises” in which the agent cannot promise arbitrarily large payments in some states. There is a superpositive pricing rule that can assign positive price to claims in zero probability states important to the market as well as assigning positive prices to claims in the states of positive probability. With continuous information arrival, no empty promises can be enforced by shutting down the agent's subsequent investments once wealth hits zero.

Portfolio turnpike theorems show that if preferences at large wealth levels are similar to power utility, then the investment strategy converges to the power utility strategy as the horizon increases. We state and prove two simple and general portfolio turnpike theorems. Unlike existing literature, our main result does not assume independence of returns and depends only on discounting of future cash flows. We also provide a critique of portfolio turnpike results, based on the observations that (1) the time required for convergence is often too large to be relevant, and (2) there is no convergence for consumption withdrawal problems. Article published by Oxford University Press on behalf of the Society for Financial Studies in its journal, The Review of Financial Studies.