al. (2017), we evaluate and confirm two core claims of the superstar firm hypothesis: the concentration of sales among … firms within industries has risen across much of the private sector; and industries with larger increases in concentration …

firms in each industry, product market concentration will rise as industries become increasingly dominated by superstar … increasingly concentrate in a small number of firms; industries where concentration rises most will have the largest declines in … share will be greatest in the sectors with the largest increases in market concentration; and finally, such patterns will be …