We study the determination of market power at the firm and industry levels when heterogeneous firms compete for sales to ex ante homogeneous buyers in a market with both directed and random search and free entry of firms that differ in productivity. Search and the distribution of productivity...

"Shimer's calibrated version of the Mortensen-Pissarides model generates unemployment fluctuates much smaller than the data. Hagedorn and Manovskii present an alternative calibration that yields fluctuations consistent with the data, but this has been challenged by Costain and Reiter, who say it...