Competition and the relative productivity of large and small firms

Using a comprehensive dataset on the incidence of price-fixing across British manufacturing industries in the 1950s, I compare collusive and competitive industries and find evidence of a negative relationship between collusion and the labour productivity of larger firms relative to smaller firms. In particular, collusion is associated with a reduction or even a reversal of the productivity gap between larger and smaller firms. This result is robust to controlling for the potential endogeneity of collusion.