Since around 2000, U.S. aggregate productivity growth has slowed and product market concentration has risen. To explain these facts, I construct a measure of innovativeness based on patent data that is comparable across firms and over time and show that small firms make innovations that are more...

Since around 2000, U.S. aggregate productivity growth has slowed and product market (sales) concentration has risen. At the same time, productivity differences among firms in the same sector appear to have risen dramatically. In this paper I propose a rich model of competition and innovation to...

Since around 2000, U.S. aggregate productivity growth has slowed and product market (sales) concentration has risen. At the same time, productivity differences among firms in the same sector appear to have risen dramatically. Sector-level data shows correlations between rising productivity gaps,...