The US labour market has experienced a remarkable polarization in the 1980s and 1990s. Moreover, recent empirical work has documented a sharp increase in the wealth to income ratio in that period. Contemporary to these inequality trends, the US faced a fast technological catch-up as European...

We study the gains from trade in a model with oligopolistic competition, heterogeneous firms and innovation, and provide a formula to decompose the mechanism. The new insight we provide is that market concentration can be a welfare-relevant feature of market power above and beyond markup...