We show how the timing of financial innovation might have contributed to the mortgage boom and then to the bust of 2007-2009. We study the effect of leverage, tranching, securitization and CDS on asset prices in a general equilibrium model with collateral. We show why tranching and leverage tend...

This is the graduation speech I gave on receiving an honorary doctorate at the University of Athens Economics and Business School. I talk about my Greek family, about how I got interested in economics, and then how in the 1990s I came to think about default, collateral, and leverage as the...

We discuss how leverage can be monitored for institutions, individuals, and assets. While traditionally the interest rate has been regarded as the important feature of a loan, we argue that leverage is sometimes even more important. Monitoring leverage provides information about how risk builds...

We show how the timing of financial innovation might have contributed to the mortgage bubble and then to the crash of 2007-2009. We show why tranching and leverage first raised asset prices and why CDS lowered them afterwards. This may seem puzzling, since it implies that creating a derivative...

Standard Fama-French and Carhart models produce economically and statistically significant nonzero alphas even for passive benchmark indices such as the S&P 500 and Russell 2000. We find that these alphas primarily arise from the disproportionate weight the Fama-French factors place on small...

The use of equilibrium models in economics springs from the desire for parsimonious models of economic phenomena that take human reasoning into account. This approach has been the cornerstone of modern economic theory. We explain why this is so, extolling the virtues of equilibrium theory; then...

Substantial progress has been made in extending the Black-Scholes model to incorporate such features as stochastic volatility, stochastic interest rates and jumps.On the empirical front, however, it is not yet known whether and by how much each generalized feature will improve option pricing and...

Substantial progress has been made in extending the Black- Scholes model to incorporate such features as stochastic volatility, stochastic interest rates and jumps. On the empirical front, however, it is not yet known whether and by how much each generalized feature will improve option pricing...

This article empirically analyzes some properties shared by all one-dimensional diffusion option models. Using S&P 500 options, we find that when sampled intraday (or inter-day), (i) call (put) prices often go down (up) even as the underlying price goes up, and (ii) call and put prices often...

Recent empirical studies find that once an option pricing model has incorporated stochastic volatility, allowing interest rates to be stochastic does not improve pricing or hedging any further while adding random jumps to the modeling framework only helps the pricing of extremely short-term...