The Ramsey approach to policy analysis finds the best competitive equilibrium given a set of available instruments. This approach is silent about unique implementation, namely designing policies so that the associated competitive equilibrium is unique. This silence is particularly problematic in monetary policy environments where many ways of specifying policy lead to indeterminacy. We show that sophisticated policies which depend on the history of private actions and which can differ on and off the equilibrium path can uniquely implement any desired competitive equilibrium. A large literature has argued that monetary policy should adhere to the Taylor principle to eliminate indeterminacy. Our findings say that adherence to the Taylor principle on these grounds is unnecessary. Finally, we show that sophisticated policies are robust to imperfect information.

In standard approaches to monetary policy, interest rate rules often lead to indeterminacy. Sophisticated policies, which depend on the history of private actions and can differ on and off the equilibrium path, can eliminate indeterminacy and uniquely implement any desired competitive equilibrium. Two types of sophisticated policies illustrate our approach. Both use interest rates as the policy instrument along the equilibrium path. But when agents deviate from that path, the regime switches, in one example to money; in the other, to a hybrid rule. Both lead to unique implementation, while pure interest rate rules do not. We argue that adherence to the Taylor principle is neither necessary nor sufficient for unique implementation with pure interest rate rules but is sufficient with hybrid rules. Our results are robust to imperfect information and may provide a rationale for empirical work on monetary policy rules and determinacy.

An examination of the behavior of stock returns around quarterly earnings announcement dates finds a seasonal pattern: small firms show large positive abnormal returns and a sizable increase in the variability of returns around these dates. Only part of the large abnormal returns can be accounted for by the fact that firms with good news tend to announce early. Large firms show no abnormal returns around announcement dates and a much smaller increase in variability.

Here we reply to Robert Solow’s comment on our work, Modern Macroeconomics in Practice: How Theory is Shaping Policy.

We study cooperative optimal Ramsey equilibria in the open economy addressing classic policy questions: Should restrictions be placed to free trade and capital mobility? Should capital income be taxed? Should goods be taxed based on origin or destination? What are desirable border adjustments? How can a Ramsey allocation be implemented with residence-based taxes on assets? We characterize optimal wedges and analyze alternative policy implementations.

Innovative activities have public good characteristics in the sense that the cost of producing the innovation is high compared to the cost of producing subsequent units. Moreover, knowledge of how to produce subsequent units is widely known once the innovation has occurred and is, therefore, non-rivalrous. The main question of this paper is whether mechanisms can be found which exploit market information to provide appropriate incentives for innovation. The ability of the mechanism designer to exploit such information depends crucially on the ability of the innovator to manipulate market signals. We show that if the innovator cannot manipulate market signals, then the efficient levels of innovation can be implemented without deadweight losses–for example, by using appropriately designed prizes. If the innovator can use bribes, buybacks, or other ways of manipulating market signals, patents are necessary.

In this paper, we characterize those situations in which after the introduction of futures markets there is either an unambiguous change in the volatility of spot prices or an unambiguous change in welfare. We provide examples of the usefulness of this approach by giving two alternative sets of sufficient conditions for price volatility to decline following the introduction of futures trading. We also provide a set of sufficient conditions for the introduction of futures trading to increase the welfare of all agents.

We find conditions for the Friedman rule to be optimal in three standard models of money. These conditions are homotheticity and separability assumptions on preferences similar to those in the public finance literature on optimal uniform commodity taxation. We show that there is no connection between our results and the result in the standard public finance literature that intermediate goods should not be taxed.

This paper studies the quantitative properties of fiscal and monetary policy in business cycle models. In terms of fiscal policy, optimal labor tax rates are virtually constant and optimal capital income tax rates are close to zero on average. In terms of monetary policy, the Friedman rule is optimal—nominal interest rates are zero—and optimal monetary policy is activist in the sense that it responds to shocks to the economy.