What this research found
How concentrated is the US passenger-airline industry, and where is it heading? Pulling audited FY2023 revenue figures from the Form 10-K filings of all ten publicly-traded US passenger carriers, K-Dense sized the market at $224.9 billion, split it into passenger, cargo, and ancillary submarkets, and measured concentration. The industry scores a Herfindahl-Hirschman Index of 1,973.5 — moderately concentrated by US antitrust standards — and is projected to reach roughly $272.5 billion by FY2028 on a 3.9% compound annual growth rate.
- The ten covered carriers generated $224,862,690,000 in FY2023 operating revenue, which the analysis adopts as the industry total addressable market. Every carrier uses a December 31 year-end, so the figures cover identical 12-month periods.
- Revenue is overwhelmingly fare-driven: the passenger submarket is $202.2B (89.9% of the total), other/ancillary is $19.2B (8.5%), and cargo/freight is just $3.5B (1.5%).
- The industry HHI of 1,973.5 sits in the 1,500-2,500 'moderately concentrated' band of the DOJ/FTC Horizontal Merger Guidelines. Delta, United, and American each contribute roughly 550-670 points and together account for about 84% of the index, while the six smallest carriers add fewer than 40 points combined.
- The top three are within 2.4 percentage points of each other — Delta at 25.8%, United at 23.9%, American at 23.5% — with Southwest a distant fourth at 11.6% and Alaska fifth at 4.6%. The top five hold 89.4% of revenue; the remaining five carriers split 10.6%.
- Concentration is tighter inside the narrow submarkets than across the industry overall. Cargo qualifies as highly concentrated (HHI 2,938, CR4 94.9%) with United alone holding 43% of it, and other/ancillary reaches HHI 2,684 on Delta's loyalty and co-brand revenue.
- The five-year projection has ancillary revenue growing fastest at 5.5% CAGR to $25.1B and cargo slowest at 1.8% to $3.8B, with passenger revenue at 3.8% to $243.6B.
How it was done
Total operating revenue for each of the ten publicly-traded US passenger airlines was extracted directly from the audited XBRL instance documents of their FY2023 Form 10-K filings on SEC EDGAR, avoiding display-scale ambiguity between carriers reporting in millions versus thousands. Submarkets were built from each carrier's own ASC 606 revenue-recognition disaggregation, tagged by XBRL product-or-service dimension, so passenger plus cargo plus other reconciles exactly to total operating revenue for every carrier. Market shares, the Herfindahl-Hirschman Index, and four- and five-firm concentration ratios were computed on those revenues, then each submarket was projected five years forward at a constant CAGR anchored to the FAA Aerospace Forecast and IATA air-cargo outlooks. All 44 market-sizing figures carry per-number citations recording the statement or note, line-item caption, XBRL concept, and filing accession number.
Data sources
- SEC EDGAR — FY2023 Form 10-K XBRL filings for 10 publicly-traded US passenger airlines
- FAA Aerospace Forecast FY2024-2044 — revenue-passenger-mile and available-seat-mile growth benchmarks
- IATA air-cargo outlooks, 2023-2024
- BTS Form 41 and carrier 10-K loyalty disclosures
Limitations
Because the HHI covers only the ten publicly-traded carriers, it is an upper bound on national concentration; adding smaller and privately held operators would lower it. Cargo is recorded as $0 for the five carriers that fold freight into 'Other', ultra-low-cost carriers book large baggage and non-fare amounts inside their passenger line, and the FY2028 projections are illustrative extrapolations from published benchmarks rather than company guidance.
How this research was produced
K-Dense Web planned and ran this business investigation end to end — gathering the sources, carrying out the analysis, producing the figures, and drafting the report. The full session transcript, including every intermediate step, is available to view.
