If firm sizes have a small dispersion, microeconomic shocks lead to negligible aggregate fluctuations. This has led economists to appeal to macroeconomic (sectoral or aggregate shocks) shocks to explain aggregate fluctuations. However, the empirical distribution of firms is fat-tailed. This...

``Limits of Arbitrage" theories require that the marginal investor in a particular asset market be a specialized arbitrageur. Then the constraints faced by this arbitrageur (i.e. capital constraints) feed through into asset prices. We examine the mortgage-backed securities (MBS) market in this...

In many markets consumer biases do not affect prices, since competition forces firms to price their products close to marginal cost; competition protects the consumer. We show that noisy consumer product evaluations undermine the force of competition, enabling firms to charge high mark-ups in...