A Theory of Falling Growth and Rising Rents
Abstract
Growth has fallen in the U.S., while firm concentration and profitshave risen. Meanwhile, labor’s share of national income is down, mostly
due to the rising market share of low labor share firms. We propose a
theory for these trends in which the driving force is falling firm-level costs
of spanning multiple markets, perhaps due to accelerating IT advances. In
response, the most efficient firms (with higher markups) spread into new
markets, thereby generating a temporary burst of growth. Because their
efficiency is difficult to imitate, less efficient firms find markets more
difficult to enter profitably and therefore innovate less. Eventually, due to
greater competition from efficient firms, within-firm markups actually fall.
Despite the increase in the aggregate markup and rents, firm incentives to
innovate decline—lowering the long run growth rate.