Two thirds of US unemployment volatility is due to fluctuations in workers' job finding rate. In search and matching models, aggregate productivity shocks generate such fluctuations: through firms recruiting effort, they affect the rate at which workers and firms come into contact....

I study a version of the search-theoretic model of imperfect competition by Burdett and Judd (1983) in which sellers face a strictly increasing rather than a constant marginal cost of production. The equilibrium exists and is unique, and its structure depends on the extent of search frictions....

I derive a formula for the equilibrium distribution of markups in the search- theoretic model of imperfect competition of Butters (1977), Varian (1980), and Burdett and Judd (1983). The level of markups and the sign of the relationship between a seller's markup and its size depends on the extent...