In this paper I present an explanation to the fact that in the data wealth is substantially more concentrated than income. Starting from the observation that the composition of households' portfolios changes towards a larger share of high-yield assets as the level of net worth increases, I first...

Using two comprehensive datasets on population of cities (1800-2000) and metropolitan areas (1960-2000) for a large set of countries, I present three new empirical facts about the evolution of city growth. First, the distribution of cities growth rates is skewed to the right in most countries...

This paper analyzes the existence of efficient equilibrium allocations in an economy with many convex and non-convex firms. A Social Equilibrium is defined as a price vector and an allocation satisfying the following properties: a) Consumers satisfy their preferences, subject to their budget...

The purpose of this paper is to offer an exposition of the results on the existence and optimality of equilibria when production sets are not assumed to be convex, in a general equilibrium framework. We aim at providing a formal and systematic account of the main results available, rather than...