This paper presents a model that generates procyclical search, procyclical labor productivity, and countercyclical unemployment broadly consistent with the actual behavior of these time series. Concretely, the model introduces an aggregate shock into the sectoral demand-shift model of the type analyzed by Lucas and Prescott. If aggregate shocks operate multiplicatively and are autocorrelated, the payoff to unemployed search can be procyclical to an extent large enough to offset the productive losses associated with search that also are procyclical.

The paper presents a "micro " shock explanation of aggregate risk. Shocks are independent over agents, and equilibria are always unique. It is shown that any amount of aggregate risk can be generated by games in which shocks to players are independent. Explicit examples are given, some of which elaborate on examples in the literature. Implications are drawn for factor-analytic methods of extracting aggregate shocks. I.

This paper explores a model of innovation and spatial competition over time. A key implication of the paper is that firms' size is positively autocorrelated across time. The mechanism that generates this persistence works only in heterogenous-product markets and is based on the idea that larger firms possess better information about the design of future products. Some corroborating evidence is cited.