This article has developed a new model of welfare dynamics under imperfect information or imperfect competition by introducing a new concept of ‘inefficient welfare equilibrium’. It assumes that an economy can be split into two virtual parts. For one part the fundamental welfare theorems are...

This paper articulates a logical foundation-drawn from disparate literatures-for understanding why safeguarding financial stability is an important economic policy objective. The paper also explains why private aspects of finance provide broader social economic benefits and have the...

In this paper, we provide a characterization of interim inefficiency in stochastic economies of overlapping generations under possibly sequentially incomplete markets. With respect to the established body of results in the literature, we remove the hypothesis of two-period horizons, by...

A 'folk theorem' originating, among others, in the work of Stiglitz maintains that competitive equilibria are always or 'generically' inefficient (unless contracts directly specify consumption levels as in Prescott and Townsend, thus bypassing trading in anonymous markets). This paper critically...

We prove indeterminacy of competitive equilibrium in sequential economies, where limited commitment requires the endogenous determination of solvency constraints preventing debt repudiation (Alvarez and Jermann (2000)). In particular, we show that, for any arbitrary value of social welfare in...

This paper argues that the introduction of a short-sale constraint in the Arrow-Radner framework invalidates standard definitions of complete and incomplete markets. Two threshold values with familiar properties arise in this constrained set-up. If short sales are not allowed on some security,...

The paper analyzes a two period general equilibrium model with individual risk, aggregate uncertainty and moral hazard. There is a large number of households, each facing two individual states of nature in the second period. These states differ solely in the household's vector of initial...

This paper defines and studies optimality in a dynamic stochastic economy with finitely lived agents, and investigates the optimality properties of an equilibrium with or without sequentially complete markets. Various Pareto optimality concepts are considered, including interim and ex ante...

In an exchange economy under uncertainty with two periods, one physical good, and finitely many states of the world, we show that for every (complete or incomplete) market span there exists a sequence of securities such that if they are introduced into markets one by one, the prices of any...

Typical models of bankruptcy and collateral rely on incomplete asset markets. In fact, bankruptcy and collateral add contingencies to asset markets. In some models, these contingencies can be used by consumers to achieve the same equilibrium allocations as in models with complete markets. In...