Does the presence of arbitrageurs decrease equilibrium asset price volatility? I study an economy with arbitrageurs, informed investors, and noise traders. Arbitrageurs face a trade-off between “inference” and “arbitrage”: they would like to buy assets in response to temporary price declines—the arbitrage effect—but sell when prices decline permanently—the inference effect. In equilibrium, the presence of arbitrageurs increases volatility when the inference effect dominates the arbitrage effect. From a technical point of view, the paper offers closed form solutions to a dynamic equilibrium model with asymmetric information and non-Gaussian priors.

[We present a dynamic contracting model in which the principal and agent disagree about the resolution of uncertainty, and we illustrate the contract design in an application with Bayesian learning. The disagreement creates gains from trade that the principal realizes by transferring payment to states that the agent considers relatively more likely, changing incentives. The interaction between incentive provision and learning creates an intertemporal source of "disagreement risk" that alters optimal risk sharing. There is an endogenous regime shift between economies with small and large belief differences, and an early shock to beliefs can lead to large persistent differences in variable pay even after beliefs have converged. Under risk-neutrality, "selling the firm" to the agent does not implement the first-best because it precludes state-contingent trades.]

We present a dynamic contracting model in which the principal and the agent disagree about the resolution of uncertainty, and we illustrate the contract design in an application with Bayesian learning. The disagreement creates gains from trade that the principal realizes by transferring payment to states that the agent considers relatively more likely, a shift that changes incentives. In our dynamic setting, the interaction between incentive provision and learning creates an intertemporal source of "disagreement risk" that alters optimal risk sharing. An endogenous regime shift between economies with small and large belief differences is present, and an early shock to beliefs can lead to large persistent differences in variable pay even after beliefs have converged. Under risk-neutrality, "selling the firm" to the agent does not implement the first-best outcome because it precludes state-contingent trades.

In a market-based financial system, banking and capital market developments are inseparable, and funding conditions are closely tied to fluctuations in the leverage of market-based financial intermediaries. Offering a window on liquidity, the balance sheet growth of broker-dealers provides a sense of the availability of credit. Contractions of broker-dealer balance sheets have tended to precede declines in real economic growth, even before the current turmoil. For this reason, balance sheet quantities of market-based financial intermediaries are important macroeconomic state variables for the conduct of monetary policy.