Top 10% of Firms Capture 90% of Profit Growth Between 1980-2000, Documenting Monopolization

Economic research documents dramatic profit concentration during the 1980-2000 period, with the top 10% of firms capturing approximately 90% of profit growth while the remaining 90% of companies see minimal gains. This concentration accelerates sharply in the post-2000 period, with the Herfindahl-Hirschman Index (HHI) increasing in over 75% of U.S. industries and average concentration levels rising by 90% in the 21st century. The ratio of after-tax corporate profits to value added rises from an average of 7% (1970-2002) to 10% post-2002, representing extraction of economic rents through market power rather than competitive returns on productive investment. Corporate markups—the amount firms charge above marginal costs—triple between 1980 and 2015, rising from 21% above costs to 61% above costs, with firm-revenue-weighted average markups increasing from 1.28 in 2000 to 1.36 in 2015. Critically, the nature of concentration changes over time: during the 1990s, concentration correlates positively with productivity growth, suggesting efficiency-driven consolidation and tougher price competition; after 2000, the correlation becomes negative, indicating rent-seeking behavior, decreasing competition, and increasing barriers to entry. This shift from ‘good’ concentration (productive efficiency) to ‘bad’ concentration (monopolistic extraction) explains rising inequality, as dominant firms use market power to suppress wages (monopsony power), squeeze suppliers, raise consumer prices (monopoly power), and extract economic rents rather than delivering competitive returns. The 90% profit concentration represents systematic wealth transfer from competitive markets to dominant firms with pricing power and market control.

SOURCE-VERIFICATION FLAG (2026-08-28, corpus audit audit-high-importance-confirmed-canon-for-source-claim-mismatch)

Flagged clause — the title and lede claim: “the top 10% of firms capturing approximately 90% of profit growth” during 1980-2000.

Finding: claim-not-in-source. Two of the three cited sources were read in full and contain no such figure:

• Grullon/Larkin/Michaely, Are US Industries Becoming More Concentrated? (NYU Stern PDF text layer, 149,386 chars / ~37,346 tokens, exact) — zero matches for top 10%|top 10 percent|90% of profit|90 percent of profit|profit growth.
• NBER Reporter, The Economics and Politics of Market Concentration (~25,862 tokens, successful read, correct subject) — zero matches for top 10|90 percent|90%|1980|Herfindahl|HHI|75 percent|75%|profit growth.
• Harvard concentration100years_3.pdf — HTTP 403, unchecked, not a negative.

What the sources actually say (and what the entry gets right): the Stern paper supports HHI rising in over 75% of US industries and average concentration levels rising by ~90% — a concentration-level statistic, not a share of profit growth — and it is a post-2000 / 1980-2014 finding, not a 1980-2000 one. The body’s after-tax-profits-to-value-added 7%→10% figure is supported by the NBER piece.

Disposition: status downgraded confirmed → disputed. The headline statistic is the entry’s organizing claim and is not carried by any readable cited source; the underlying monopolization finding is real and well-sourced. Do not delete — retitle around the supported “HHI up in >75% of industries, average concentration +90%” statistic, or locate the actual source of the top-10%/90%-of-profit-growth figure before restoring.