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This paper studies an overlapping generations model with stochastic production and incomplete markets to assess whether the introduction of an unfunded social security system leads to a Pareto improvement. When returns to capital and wages are imperfectly correlated, a system that endows retired households with claims to labor income enhances the sharing of aggregate risk between generations. Our quantitative analysis shows that, abstracting from the capital crowding-out effect, the introduction of social security represents a Pareto-improving reform, even when the economy is dynamically efficient. However, the severity of the crowding-out effect in general equilibrium tends to overturn these gains.

Many assets derive their value not only from future cash flows but also from their ability to serve as collateral. In this article, we investigate this collateral premium and its impact on asset returns in an infinite-horizon general equilibrium model with heterogeneous agents. We document that borrowing against collateral substantially increases the return volatility of long-lived assets. Moreover, otherwise identical assets with different degrees of collateralizability exhibit substantially different return dynamics because their prices contain a sizable collateral premium that varies over time. This premium can be positive even for assets that never pay dividends.

In this article we examine the competitive equilibria of a dynamic stochastic economy with complete markets and collateral constraints. We show that, provided the sets of asset pay-offs and of collateral levels are sufficiently rich, the equilibrium allocations with sequential trades and collateral constraints are equivalent to those obtained in Arrow-Debreu markets subject to a series of limited pledgeability constraints. We provide both necessary and sufficient conditions for equilibria to be Pareto efficient and show that when collateral is scarce equilibria are not only Pareto inefficient but also often constrained inefficient, in the sense that imposing tighter borrowing restrictions can make everybody in the economy better off. We derive sufficient conditions for the existence of Markov equilibria and, for the case of two agents, for the existence of equilibria that have finite support. These equilibria can be computed with arbitrary accuracy and the model is very tractable.

Carbon taxation is mostly studied in social planner or infinitely lived-agent models, which obscure carbon taxation’s potential to produce a generational win win. This article’s large-scale, dynamic 55-period, overlapping generations model calculates the carbon tax policy delivering the highest uniform welfare gain to all current and future generations. Our model features coal, oil, and gas, increasing extraction costs, clean energy, technical and demographic change, and Nordhaus’ carbon/temperature/damage functions. Assuming high-end carbon damages, the optimal carbon tax is $70, rising annually at 1.5%. This policy raises all generations’ welfare by almost 5%. However, doing so requires major intergenerational redistribution.

The demand for assets as prices and initial wealth vary identifies beliefs and attitudes towards risk. We derive conditions that guarantee identification with no knowledge either of the cardinal utility index (attitudes towards risk) or of the distribution of future endowments or payoffs of assets; the argument applies even if the asset market is incomplete and demand is observed only locally.

In this paper, we prove the existence of recursive equilibria in a dynamic stochastic model with infinitely lived heterogeneous agents, several commodities, and general inter- and intratemporal production. We illustrate the usefulness of our result by providing sufficient conditions for the existence of recursive equilibria in heterogeneous agent versions of both the Lucas asset pricing model and the neoclassical stochastic growth model.

We provide conditions under which contingent claim and asset demands are consistent with state independent Expected Utility maximization. The paper focuses on the case of a single commodity and demands are allowed to be functions of probabilities and not just prices and income. We extend prior analyses by deriving three distinct tests for demands to be rationalized by Expected Utility: (i) a contingent claim analogue to the certainty strong axiom of revealed preference, (ii) a characterization of the functional form for demand, and (iii) necessary and sufficient conditions based on the Slutsky matrix.

We compare asset prices in an overlapping generations model for incomplete and complete markets. Individuals within a generational cohort have heterogeneous beliefs about future states of the economy and thus would like to make bets against each other. In the incomplete-markets economy, agents cannot make such bets. Asset price volatility is very small. The situation changes dramatically when markets are completed through financial innovations as the set of available securities now allows agents with different beliefs to place bets against each other. Wealth shifts across agents and generations. Such changes in the wealth distribution lead to substantial asset price volatility.

In this paper, I examine ε-equilibria of stationary dynamic economies with heterogeneous agents and possibly incomplete financial markets. I give a simple example to show that even for arbitrarily small ε > 0, allocation and prices can be far away from exact equilibrium allocations and prices. That is, errors in market clearing or individuals' optimality conditions do not provide enough information to assess the quality of an approximation. I derive a sufficient condition for an ε-equilibrium to be close to an exact equilibrium. If the economic fundamentals are semi-algebraic, one can verify computationally whether this condition holds. The condition can be interpreted economically as a robustness requirement on the set of ε-equilibria which form a neighbourhood of the computed approximation. I illustrate the main result and the computational method using an infinite horizon economy with overlapping generations and incomplete financial markets.

Assuming the classic contingent claim setting, a number of financial asset demand tests of Expected Utility have been developed and implemented in experimental settings. However, the domain of preferences of these asset demand tests differ from the mixture space of distributions assumed in the traditional binary lottery laboratory tests of von Neumann-Morgenstern Expected Utility preferences. We derive new sets of axioms for preferences over contingent claims to be representable by an Expected Utility function. We also indicate the additional axioms required to extend the representation to the more general case of preferences over risky prospects.