The optimal portfolio of a utility-maximizing investor trading in the S&P 500 index and cash, subject to proportional transaction costs, becomes stochastically dominated when overlaid with a zero-net-cost portfolio of S&P 500 options bought at their ask and written at their bid price in most...

The optimal portfolio of a utility-maximizing investor trading in the S&P 500 index and cash, subject to proportional transaction costs, becomes stochastically dominated when overlaid with a zero-net-cost portfolio of S&P 500 options bought at their ask and written at their bid price in most...

We document widespread violations of stochastic dominance in the one-month S&P 500 index options market over the period 1986-2002. These violations imply that a trader can improve her expected utility by engaging in a zero-net-cost trade. We allow the market to be incomplete and also imperfect...

We document that the implied volatility skew of S&P 500 index puts is non-decreasing in the disaster index and risk-neutral variance, contrary to the implications of a broad class of no-arbitrage models. The key to the puzzle lies in recognizing that, as the disaster risk increases, customers...

We document that leverage-adjusted returns on S&P 500 index call and put portfolios are decreasing in their strike-to-price ratio over 1986-2010, contrary to the prediction of the Black-Scholes-Merton model. We test a large number of plausible unconditional factor models and find that only...