Work by Spencer Kwon, Yueran Ma and Kaspar Zimmermann
We measure concentration among production activities in the U.S. by digitizing the size distribution of all U.S. corporate businesses from 1918 to 2018.
For the aggregate economy, the share of top businesses has been consistently increasing for the past 100 years.
This figure shows the shares of top 1% (first panel) and top 0.1% (second panel) corporate business. The red line with triangles shows the share of assets accounted for by top businesses sorted on assets. The green line with squares shows the share of sales accounted for by top businesses sorted on sales. The light blue line with circles shows the share of net income accounted for by top businesses sorted on net income (restricting to those with positive net income).
Rising concentration occurred in most industries, but with different timing.
The phenomenon was stronger in manufacturing in earlier decades, and stronger in services and trade (retail and wholesale) in later decades.