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Working Paper
Bubbles as payoffs at infinity
We define rational bubbles to be securities with payoffs occurring in the infinitely distant future and investigate the behavior of bubble values. We extend our analysis to a setting of uncertainty. In an infinite-horizon arbitrage-free model of asset prices, we interpret the money market account as the value of a particular bubble; a similar interpretation holds for other assets related to the state-price deflator and to payoffs on bonds maturing in the distant future. We present three applications of this characterization of bubbles.
Journal Article
Risky mortgages and mortgage default premiums
Mortgage lenders impose a default premium on the loans they originate to compensate for the possibility that borrowers won?t make payments. The housing boom of the 2000s was characterized by increasing riskiness of the borrowers approved for mortgages and the structures of the loans themselves. Despite these changes in risk, a pricing model can justify the spreads contained in mortgages made during this period based on what at the time seemed to be reasonable expectations for house price appreciation. Contrary to those expectations, prices fell dramatically.
Discussion Paper
Determining the monetary instrument: a diagrammatic exposition
Working Paper
Stochastic bubbles in Markov economies
Journal Article
Convex payoffs: implications for risk-taking and financial reform
Financial executive pay is a convex function of profits if recipients get a greater increment in pay when returns are high as opposed to moderate, compared with when returns are moderate as opposed to low. Convex compensation packages give financial executives incentive to adopt risky investment projects, implement highly levered capital structures, and create new risk. Financial regulators may be able to enforce changes in compensation that would attenuate these adverse effects.
Journal Article
Capital market efficiency: an update
Journal Article
Can risk aversion explain stock price volatility?
Why are the prices of stocks and other assets so volatile? Efficient capital markets theory implies that stock prices should be much less volatile than actually observed, reflecting an unrealistic assumption that investors are risk neutral. If instead investors are assumed to be risk averse, predicted volatility is higher. However, models that incorporate investor avoidance of risk can explain real-world stock price volatility only under levels of risk aversion that are unrealistically high. Thus, price volatility remains unexplained.
Working Paper
Mortgage default and mortgage valuation
We study optimal exercise by mortgage borrowers of the option to default. Also, we use an equilibrium valuation model incorporating default to show how mortgage yields and lender recovery rates on defaulted mortgages depend on initial loan-to-value ratios when borrowers default optimally. The analysis treats both the frictionless case and the case in which borrowers and/or lenders incur deadweight costs upon default. The model is calibrated using data on California mortgages. We find that the model's principal testable implication for default and mortgage pricing?that default rates and yield ...