While a few large corporations often dominate headlines, research reveals a broader trend: industries across the economy have become more concentrated, with not only the biggest firms but also mid-sized ones expanding their market share. This shift is not a recent phenomenon: Since the 1930s, the share of the U.S. economy controlled by the top 1% of companies (ranked by assets) has risen from 70% to 90%. Even more strikingly, the top 0.1% share has doubled, increasing from 47% to 88%.

The pace of concentration has varied by industry. Before the 1970s, manufacturing and mining saw the most growth in corporate dominance due to mass production and economies of scale, which helped reduce fixed costs. After the 1970s, industries like retail, wholesale, and services experienced greater concentration, fuelled by advances in information technology. Across multiple measures, the dominance of large firms has increased steadily over the past century. In addition to asset concentration, revenue share among the largest companies has grown significantly. The top 1% of firms by sales now account for 80% of total revenues, up from 60% in 1970. Although the share of net income has fluctuated, the long-term trend is clear: by 1975, the top 1% of firms by net income were earning $8 of every $10 made by U.S. corporations, compared to $6 of every $10 five decades earlier (Jacobs, 2022).

This trend is not limited to the United States. Between 1998 and 2019, the market share of the four largest firms increased in 73% of approximately 700 industries across Europe, with an average growth of seven percentage points. The proportion of industries where the top four firms controlled more than half of the market rose from 16% to 27%, with the most significant increases observed in Britain and France. Simultaneously, incumbent firms have become more entrenched. In Britain, the average number of firms that remained in the top ten of their industries by market share after three years was five before the financial crisis; this figure has since risen to nearly eight (Wars, 2023).