Hart proved the difficulty of deriving general comparative statics in portfolio weights. Instead, we derive new comparative statics for the distribution of payoffs: A is less risk averse than B iff A's payoff is always distributed as B's payoff plus a non-negative random variable plus...

We propose a tractable equilibrium model to examine how margin requirements affectasset prices, market volatility, and market participants' welfare. Weshow that margin requirements can have opposite effects on market volatility whenthey constrain different investors and thus can help explain why...

Market makers in some financial markets often make offsetting trades and have significant market power. We develop a market making model that captures these market features as well as other important characteristics such as information asymmetry and inventory risk. In contrast to the existing...

We study return predictability using a model of speculative trading among relatively overconfident competitive traders who agree to disagree about the precision of their private information. Although traders apply Bayes Law consistently, returns are predictable. In addition to trading on...

We study the impact of short-sale constraints on market prices and liquidity in imperfectly competitive markets in which market-makers have market power. We show that, with or without information asymmetry, short-sale constraints decrease bid prices, but increase bid-ask spreads and...

We describe a symmetric continuous-time model of trading among relatively overconfident, oligopolistic informed traders with exponential utility. Traders agree to disagree about the precisions of their continuous flows of Gaussian private information. The price depends on a trader's inventory...

Most existing portfolio choice models ignore the prevalent periodic market closure and the fact that market volatility is significantly higher during trading periods. We find that market closure and the volatility difference across trading and nontrading periods significantly change optimal...