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Evolving Differences Among Publicly-Traded Firms in the United States, 1960-2015

I use data on all publicly traded firms in the United States to document the evolving differences between large and small firms over the period covering 1960 to 2015. Focusing separately on the financial and non-financial sectors, I document patterns related to the number of active publicly-traded firms; size differences between the firms at the 10th and 90th percentiles; the share of sales and assets held by firms at the top of the distribution; the behavior of entrants; volatility differences among small and large firms; the significance of the technology sector; and the sectoral affiliation of publicly-traded firms. I find evidence that, over the past 55 years, disparity (in size and volatility) between the largest and smallest firms has increased, although the picture is more complicated in the financial sector where large firms, for example, have become relatively volatile in comparison with small firms. New non-financial public companies have also become smaller relative to incumbents, while all entrants have had a smaller chance of surviving during more recent decades. My analysis also uncovers a shift away from manufacturing and towards services, retail and wholesale trade, and finance, along with the increasing prominence of high-technology industries.