In a model with heterogeneous-risk-aversion agents facing margin constraints, we show how securities' required returns are characterized both by their betas and their margin requirements. Negative shocks to fundamentals make margin constraints bind, lowering risk-free rates and raising Sharpe...

This paper studies portfolio choice and pricing in markets in which immediate trading may be impossible. It departs from the literature by removing restrictions on asset holdings, and finds that optimal positions depend significantly and naturally on liquidity: When expected future liquidity is...

I explain the key failure mechanics of large dealer banks, and some policy implications. This is not a review of the Financial crisis of 2007-2009. Systemic risk is considered only in passing. Both the Financial crisis and the systemic importance of large dealer banks are nevertheless obvious...