We develop a general equilibrium model of monopolistic competition with a traded and a non-traded sector. Using a broad class of homothetic preferences—that generate variable markups, display a simple behavior of their elasticity of substitution, and nest the ces as a limiting case—we show...

I analyze two opposing effects of firm dynamics on productivity over the business cycle. Consider net exit, on the one hand it reallocates resources to incumbents whose productivity improves through scale economies, on the other hand it reduces the competitive pressure incumbents face which...