Martine Quinzii

Core and Competitive Equilibria with Indivisibilities

The paper presents a model of an exchange economy with indivisible goods and money. There are a finite number of agents, each one initially endowed with a certain amount of money and at most one indivisible good. Each agent is assumed to have no use for more than one indivisible good. It is proved that the core of the economy is nonempty. If utility functions are increasing in money, and if the initial resources in money are in some sense “sufficient” the core allocations coincide with the competitive equilibrium allocations.With restrictions on the set of feasible allocations, the same model is used to prove the existence of stable solutions in the generalized “marriage problem”. However it is shown that, even if money enters the model, these solutions cannot generally be obtained as competitive equilibria.

Demography and the Long-Run Predictability of the Stock Market

Stock market price/earnings ratios should be influenced by demography. Since demography is predictable, stock returns should be as well. We provide a simple stochastic OLG model with a cyclical structure that generates cyclical P/E ratios. We calibrate the model to roughly fit the cyclical features of historical P/E ratios.

Infinite Horizon Incomplete Markets

This paper extends the general equilibrium model with incomplete markets to an open-ended future, thereby providing a natural setting for analyzing problems in macroeconomics. Two concepts of equilibrium are defined that prevent agents from entering into Ponzi schemes: the first is based on debt constraints and the second is based on a transversality condition that limits the rate of growth of debt. Under the assumption that agents are impatient (Mackey continuity of preferences) and have a degree of impatience that is bounded below, the two concepts of equilibrium are shown to coincide and lead to existence of equilibrium. Copyright 1994 by The Econometric Society.

Generic inefficiency of stock market equilibrium when markets are incomplete

A stock market is a mechanism by which the ownership and control of firms is determined through the trading of securities. It is on this market that many of the major risks faced by society are shared through the exchange of securities and the production decisions that influence the present and future supply of resources are determined. If the overall structure of markets is incomplete can the stock market be expected to perform its role of exchanging risks and allocating investment efficiently? It is this question that we seek to answer.

Real effects of money in general equilibrium

Abstract This paper studies a simple stochastic general equilibrium model with money and nominal assets. We examine the role of money as a medium of exchange and as a store of value and give conditions under which local changes in the money supply lead to local changes in the equilibrium allocation.

Incomplete markets over an infinite horizon: Long-lived securities and speculative bubbles

Abstract This paper studies sequence economies over an infinite horizon with general security structures. Assumptions are given under which a pseudo-equilibrium exists for all economies and an equilibrium exists for a dense set of (appropriately parameterized) economies. Under these assumptions the indebtedness of the agents in equilibrium can be limited either by an explicit bound on their debts or by a transversality condition limiting the asymptotic growth of their debts. The qualitative properties of equilibrium prices of infinite-lived securities are studied: the prices of infinite-lived securities in zero net supply are shown to permit speculative bubbles and the existence of bubbles can affect the equilibrium allocation. The prices of securities in positive supply (equity contracts) cannot have speculative bubbles: the extent of speculation in this class of model is thus severely limited.

Buying several indivisible goods

This paper studies economies where agents exchange indivisible goods and money. Agents have potential use for all indivisible goods and the indivisible goods are differentiated. We assume that agents have quasi-linear utilities in money, have sufficient money endowments to afford any group of objects priced below their reservation values, have reservation values which are submodular and satisfy the Cardinality Condition. This Cardinality Condition requires that for each agent the marginal utility of an object only depends on the number of objects to which it is added, not on their characteristics. Under these assumptions, we show that the set of competitive equilibrium prices is a non empty lattice and that, in any equilibrium, the price of an object is between the social value of the object and its value in its second best use.

On the Optimality of Central Places

A model of consumer multipurpose shopping is used for studying the optimality of central places. There are two different commodities sold by two different types of firms. The shopping frequencies are exogenously given and different for the two commodities. Consumers can group their purchases of the two commodities in order to reduce transport costs. It is shown that the socially optimal configuration of firms always involves the clustering of a firm type 2 (low purchase frequency) with a firm of type 1 (high purchase frequency), assuming that the number of firms of type 2 is smaller than the number of firms of type 1. Copyright 1990 by The Econometric Society.

Capital market equilibrium with moral hazard

Abstract This paper studies a general equilibrium model of an economy with production under uncertainty in which firms’ capital (ownership) structures creates a moral hazard problem for their managers. The concept of an equilibrium with rational, competitive price perceptions (RCPP) is introduced, in which investors correctly anticipate the optimal effort of entrepreneurs by observing their financial decisions, and entrepreneurs are aware that investors use their financial decisions as signals. The competitive element in the equilibrium valuation of firms comes from the fact that entrepreneurs cannot affect the market price of risks. It is shown that under appropriate spanning assumptions an RCPP is constrained Pareto optimal. Furthermore, if sufficiently many options are traded, then full optimality can be obtained despite the moral hazard problem: options serve both to increase the span of the market and to provide incentives for entrepreneurs.

A theory of the stakeholder corporation

There is a widely held view within the general public that large corporations should act in the interests of a broader group of agents than just their shareholders (the stakeholder view). This paper presents a framework where this idea can be justified. The point of departure is the observation that a large firm typically faces endogenous risks that may have a significant impact on the workers it employs and the consumers it serves. These risks generate externalities on these stakeholders which are not internalized by shareholders. As a result, in the competitive equilibrium, there is under‐investment in the prevention of these risks. We suggest that this under‐investment problem can be alleviated if firms are instructed to maximize the total welfare of their stakeholders rather than shareholder value alone (stakeholder equilibrium). The stakeholder equilibrium can be implemented by introducing new property rights (employee rights and consumer rights) and instructing managers to maximize the total value of the firm (the value of these rights plus shareholder value). If there is only one firm, the stakeholder equilibrium is Pareto optimal. However, this is not true with more than one firm and/or heterogeneous agents, which illustrates some of the limits of the stakeholder model.