Different forms of resource allocation-by markets, cooperative games, and by social choice-are unified by one condition, limited arbitrage, which defined on the endowments and the preferences of the traders of an Arrow Debreu economy. Limited arbitrage is necessary and sufficient for the...

An economy faces an unknown individual risk, such as the health effects of a recently discovered environmental hazard. Opinions may be widely different about the distribution of risks across the population. We study financial markets that suffice to reach efficient allocations in this situation....

We study endogenous uncertainty stemming from the introduction of new financial assets, so as to evaluate the risks as well as the welfare gains of financial innovation. The introduction of financial assets to hedge individual risk can lead to the risk of default, which is a collective risk. The...

It is widely recognized that the value of environmental assets such as biodiversity, unique locations and the atmosphere may be hard to quantify. In particular, option values, quasi-option values and non-use values have been the subject of extensive discussion. We propose here an evaluation of...

The formation of trading blocks can help or hinder the global liberalization of trade. A determining factor is whether trade within the block is organized around traditional comparative advantages, or around economies of scale. The issue is of particular importance for NAFTA, and for a potential...

An economy faces an unknown individual risk, such as the health effects of recently discovered environmental hazard. Opinions may be widely different about the distribution of risks across the population. We study financial markets that suffice to reach efficient allocations in this situation....

Consider an exchange economy with multiple competitive equilibria. Agents know the set of equilibria, but not which will be selected. To insure against unfavorable equilibrium outcomes, they trade on markets for commodities contingent on the equilibrium price vector. Such price-contingent...

We study the risks associated with the prospect of global climate change, and review the mechanisms available for their efficient allocation in market economies. Risks in this field are typically unknown and often unknowable ex ante; their probabilities are endogenous and determined by economic...

The paper establishes a clear connection between equilibrium theory and social choice theory by showing that, for a well defined social choice problem, the conditions which are necessary and sufficient to establish existence of a competitive equilibrium. We define a condition of limited...

A condition of limited arbitrage is defined on the endowments and the preferences of the traders in an Arrow-Debreu economy. It bounds the diversity of the traders in the economy, and the gains from trade which they can afford from initial endowments. Theorem 1 shows that limited arbitrage is...