Diverging Trends in National and Local Concentration

Research from FRBR, while market concentration has risen nationally, concentration of smaller markets as gone down. "...We have shown...that the increase in market concentration observed at the national level over the last 25 years is being shaped by enterprises expanding into new local markets. This expansion into local markets is accompanied by a fall in local concentration as firms open establishments in new locations. These observations are suggestive of more, rather than less, competitive markets...."Counterintuitively (figure 15) if you net out the largest firm, concentration is unchanged suggesting that either small business stay in business or when a big firm enters a market other big firms do as well.

"....Using U.S. NETS data, we present evidence that the positive trend observed in national product market concentration between 1990 and 2014 becomes a negative trend when we focus on measures of local concentration. We document diverging trends for several geographic definitions of local markets. SIC 8 industries with diverging trends are pervasive across sectors. In these industries, top firms have contributed to the amplification of both trends. When a top firm opens a plant, local concentration declines and remains lower for at least 7 years. Our findings, therefore, reconcile the increasing national role of large firms with falling local concentration, and a likely more competitive local environment....In this paper, we use the National Establishment Time Series (NETS) dataset to document four main facts regarding national and local product-market concentration in the U.S. economy between 1990 and 2014. Our first fact is that the observed positive trend in market concentration at the national level has been accompanied by a corresponding negative trend in average local market concentration.We measure concentration using the Herndahl-Hirschman index (HHI), but our findings hold for a variety of statistics..... The second fact shows that local concentration is falling across SIC 8 industries that together account for 78% of employment and 72% of sales.Furthermore, conditioning on industries where national concentration is rising, industries where local concentration has declined account for the majority of employment overall (72% of employment and 66% of sales) across all major sectors. The presence of these diverging trends is always large but more pronounced in services, retail trade, and FIRE relative to wholesale trade and manufacturing. This ordering is natural given that transport costs are less relevant in the latter two sectors. Together, these first two facts underscore an unmistakable decline in local concentration on average that is pervasive across all sectors..... Our third fact shows that among SIC 8 industries that exhibit this pattern, top firms have accelerated these trends. That is, excluding the top
firm in each industry (in terms of national sales in their SIC 8 industry in 2014), the national increase in concentration becomes naturally less pronounced.Perhaps more surprisingly, the decline in local concentration also becomes less pronounced.Put another way, large firms have materially contributed to the observed decline in local concentration. Among industries with diverging trends, large firms have become bigger but the associated geographic expansion of these firms, through the opening of more plants in new local markets, has lowered local concentration thus suggesting increased local competition. In the considerably smaller set of industries where we observe increases in both national and local concentration, top firms have also been responsible for both forms of concentration......Our fourth fact establishes that among industries with falling local concentration, the opening of a plant by a top firm is associated with a decline in local concentration at the time of the opening, and that this lower level of concentration persists for at least the next 7 years.This observation provides further evidence that in those industries, large enterprises do not enter and dominate the local market but instead lower its concentration, either by competing with the previous local monopolist or by simply adding one more establishment that grabs a proportional market share from other local establishments. In any case, the notion that entry by large firms eliminates local producers to the point of increasing concentration is certainly not supported in the vast majority of industries where most of U.S. employment resides...."

Rossi-Hansberg, Esteban, Pierre-Daniel Sarte, and Nicholas Trachter. April 17, 2019. “Diverging Trends in National and Local Concentration.” Federal Reserve Bank of Richmond.https://www.princeton.edu/~erossi/DTNLC.pdf