Delta Air Lines alone holds 18% of this market. HHI places a market on a 0–10,000 concentration scale. The 2023 Merger Guidelines flag anything past 1,800 as highly concentrated; this observatory classifies with the more conservative 2,500 line.
HHI is withheld here — public firm-level data isn’t sufficient for a reliable calculation.
Evidence atlas
Source to public action route
80%
Public coverage11 share rows
Live evidence packetGap namedHHI stays withheld until public shares support it
Reusable rows771 sources, 11 share rows
Public actionEvidence buildPublish firm-level shares, ownership/control links, and market-definition notes before public agencies rely on private estimates.
Data
2026
Incomplete
Packet
77 rows
1 core source
Action
Evidence build
Top firm 17.8%
Public stake
Transportation
Concentrated markets turn everyday access into private leverage.
Evidence posture
Data gap
77 reusable rows across 1 core source.
Government duty
Evidence build
Publish firm-level shares, ownership/control links, and market-definition notes before public agencies rely on private estimates.
HHI
Withheld
Classification unavailable
Top firm
17.80%
Market share
CR4
69.00%
Top 4 firms
Data status
Incomplete
Source availability
Confidence
High
Methodology limits
Review flags
2
Evidence build
Insufficient public market-share data for HHI calculation
CR4 and top carrier share can be reported from the sourced carrier rows.
Observatory market brief
Domestic airlines: a 69.0% CR4 screen, but no publishable firm-level HHI.
The latest structured aggregate is 69.0%. Individual shares do not close a firm-level distribution, so HHI remains withheld. The current public record does not provide a definition-stable firm-level HHI series.
01
Latest structure
69.0% aggregate
The latest structured aggregate is 69.0%. Individual shares do not close a firm-level distribution, so HHI remains withheld.
02
Published change
No comparable series
The current public record does not provide a definition-stable firm-level HHI series.
03
Evidence custody
3 custody records
3 records in the evidence custody chain, 11 latest share rows, 2 linked official records, and 2 related briefs support this profile. Status is incomplete with high confidence.
Comparison window
Series status
2026 evidence
The current public record does not provide a definition-stable firm-level HHI series.
Measured-market contextHHI withheldexcluded from HHI ranking
Public research question
Which individual firm shares and geographic boundaries are needed to move from aggregate concentration facts to a complete market screen?
Evidence build
Publish firm-level shares, ownership/control links, and market-definition notes before public agencies rely on private estimates.Open public-action route
Market-definition contract
Read the boundary before the metric.
This profile’s concentration claims apply only to the product, geography, denominator, and measurement basis documented below.
Agency definedhigh confidence2026 basis
Product boundary
Domestic scheduled airline passenger traffic
Geographic boundary
United States domestic itineraries
Measurement basis
Carrier share of domestic scheduled passengers
Denominator
Passengers reported in the BTS domestic market-share table for the 12 months ending February 2026
Included
Named carriers and the published aggregate Other category
Excluded
Individual carriers inside Other are not separately identified
Cross-market use
Not comparable
Time-series use
Snapshot only
Method note
Use sourced carrier passenger shares for top-firm and CR4 screens; withhold HHI while Other remains aggregated.
The aggregate Other row prevents a complete firm-level distribution and therefore prevents a publishable HHI.
Boundary source
TranStats airline domestic market share March 2025-February 2026
Bureau of Transportation Statistics · accessed 2026-05-16
Declared economy screen / navigation only
NAICS 481111 / Scheduled passenger air transportation
2022 national industry HHI 1,465.5; this does not redefine or validate the market above.
The same 0-10,000 HHI scale does not make different product, geographic, or denominator definitions economically interchangeable. Cross-market HHI is a descriptive screen only.
Evidence timeline
Follow the profile from source record to public action.
Each profile should read like an inspectable research route: source access, concentration metric, participant table, official policy chronology, briefing, and the government question it creates.
Strong public profiles are navigable. This view connects the current market to sector peers, concentration peers, and disclosure-gap peers using the public metrics already in the observatory. Node size follows published HHI; withheld HHI uses the smallest marker.
United States · 2026 · Bureau of Transportation Statistics
11 sourced rows
Delta Air Lines
17.80% share · rank 1 · Verified · high confidence
Bureau of Transportation Statistics
Tile area is proportional to each firm’s sourced market share. Hatched tiles are aggregate or residual categories, shown for coverage and excluded from firm-level screens.
Keep HHI, firm shares, trend, and evidence quality separate so researchers can inspect why this market is routed for review.
Review posture
Evidence build
Confidence
High confidence
Exact flags
2 visible
Screening rule
Review posture uses published concentration thresholds, trend direction, and evidence status as separate signals. It does not estimate consumer harm or establish legal liability.
Public implication
Publish firm-level shares, ownership/control links, and market-definition notes before public agencies rely on private estimates.
Evidence still needed
Firm-level shares and local ownership/control data
69.0% CR4 (>= 60%)Public data incomplete
Data provenance
Methodology: Show CR4 and top carrier share from sourced BTS percentages; withhold HHI because Other is not firm-level.
Limitations: CR4 and top carrier share can be reported from the sourced carrier rows.
TranStats airline domestic market share March 2025-February 2026
Bureau of Transportation Statistics
public dataset
Bureau of Transportation Statistics TranStats, Airline Domestic Market Share, March 2025-February 2026.
A compact audit of whether the profile has enough public evidence to support action.
Build evidence
Freshness2026Latest source access May 16, 2026Coverage80%11 public share rows; HHI still withheldAPI routes8Filtered public JSON endpoints for reuseSource mix1public dataset
Source mix
1 sources
public dataset1
Missing evidence
Comparable local market definitions
Firm-level owner or operator shares
Acquisition, control, and property-management links
Public evidence packet
Jump from this market profile to the filtered machine-readable rows behind the public claim.