Financial innovations that change how promises are collateralized can affect investment, even in the absence of any change in fundamentals. In C-models, the ability to leverage an asset always generates over-investment compared to Arrow Debreu. The introduction of CDS always leads to...

We show that financial innovations that change the collateral capacity of assets in the economy can affect investment even in the absence of any shift in utilities, productivity, or asset payoffs. First we show that the ability to leverage an asset by selling non-contingent promises can generate...

Afriat's original method of proof is restored by using the minmax theorem.

Our paper provides a complete characterization of leverage and default in binomial economies with financial assets serving as collateral. Our Binomial No-Default Theorem states that any equilibrium is equivalent (in real allocations and prices) to another equilibrium in which there is no...

The literature on leverage until now shows how an increase in volatility reduces leverage. However, in order to explain pro-cyclical leverage it assumes that bad news increases volatility. This paper suggests a reason why bad news is more often than not associated with higher future volatility....

Irving Fisher long advocated inflation indexed bonds. I prove in the context of a multicommodity CAPM world that the best welfare improving bond pays the minimum money needed to achieve the same utility, and not the minimum needed to buy an ideal commodity bundle. Irving Fisher also developed...

Introducing default and limited collateral into general equilibrium theory (GE) allows for a theory of endogenous contracts, including endogenous margin requirements on loans. This in turn allows GE to explain liquidity and liquidity crises in equilibrium. A formal definition of liquidity is...

This paper was begun during a visit at the Cowles Foundation in Fall 2000 and revised during a visit in Fall 2002: Michael Magill and Martine Quinzii are grateful for the stimulating environment and the research support provided by the Cowles Foundation. We are also grateful to Bob Shiller for...

Actions a firm takes in one market may affect its profitability in other markets, beyond any joint economies or diseconomies in production. The reason is that an action in one market, by changing marginal costs in a second market, may change competitors' strategies in that second market. We show...

We extend Arrow's analysis of portfolio choice in a one-period model to savings and portfolio choice in a two-period model.