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....

We study equilibrium wage and employment dynamics in a class of popular search models with wage posting, in the presence of aggregate productivity shocks. Firms offer and commit to (Markov) contracts, which specify a wage contingent on all payoff-relevant states, but must pay equally all of...

We document a negative correlation, at business cycle frequencies, between the net job creation rate of large employers and the level of aggregate unemployment that is much stronger than for small employers. The differential growth rate of employment between initially large and small employers...