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...

I develop a model of dynamic firm entry, oligopolistic competition and returns to scale in order to decompose TFP fluctuations into technical change, economic profit and markup fluctuations. I show that economic profits cause short-run upward bias in measured TFP, but this subsides to upward...