One-Insurer Dominance Fell in Individual Markets—and Rose in Small-Business Coverage

The same concentration test points in opposite directions

From 2021 through 2024, the number of states where one health insurer controlled at least 80% of individual-market enrollment fell from eight to one. During the same period, the number meeting that test in fully insured small-group coverage rose from fourteen to sixteen, and in fully insured large-group coverage rose from ten to thirteen.

What’s the Scoop With Broach reconstructed those three comparisons from the enclosure of GAO’s October 16 health-insurance concentration report. The seven-state reduction in the individual market is an 87.5% decline in the count of states meeting that threshold. It is not an 87.5% drop in any insurer’s market share, premium or enrollment.

The accountability question is whether a broad statement that insurance markets remain concentrated adequately describes where competition is improving and where dominance is deepening. The new table documents divergence: recent individual-market improvement coexists with greater single-issuer dominance in the employer markets studied.

More issuers does not necessarily mean dispersed enrollment

The small-group market’s median issuer count fell from six to five between 2021 and 2024. Over those years, the median share held by the largest single issuer rose from 58% to 66%, an eight-percentage-point increase. Its top-three median share moved only from 97% to 98%. Looking only at the top-three measure would understate the shift toward the largest carrier.

The large-group market provides a different warning about counting sellers. Its median number of issuers stayed at eight, and the top-three median share stayed at 93%. Yet states where one issuer held at least 80% increased from ten to thirteen. Stable national medians therefore do not establish that every state’s competitive structure stayed unchanged.

For the individual market, the median single-issuer share fell from 53% to 48%, and the top-three median share fell from 96% to 90%. The median issuer count remained nine. Those movements show enrollment becoming less concentrated even without an increase in the median count of participating companies.

The exchange and overall individual market are different measures

The report separately examines the individual exchanges, which are part of the broader individual market. In 2024, three or fewer issuers accounted for at least 80% of exchange enrollment in forty-nine states, compared with thirty-six states in the overall individual market. These are two different populations and calculations, not inconsistent counts.

For exchanges, GAO combines local rating-area measures into a state figure weighted by covered life-years. For the other markets, it measures statewide issuer shares. Consumers choose among plans available where they live, so a statewide number does not establish that every county or household has the same choices.

The unit also matters: GAO aggregates affiliated issuers to their parent companies rather than treating every licensed subsidiary as an independent competitor. Its enrollment measure is covered life-years, reflecting average lives insured during the year, including dependents. The report includes the District of Columbia in its fifty-one-state universe.

What the new evidence establishes—and leaves outside the frame

The group-market figures cover fully insured plans. They exclude self-funded employer plans, in which employers set aside funds to pay health-care claims rather than purchase full insurance. The report notes that roughly 63% of covered workers were in self-funded plans in 2024. Applying the fully insured concentration results to all employer coverage would overstate the scope of the evidence.

GAO explains that concentration can arise from mergers, exits, market-share changes or barriers to entry. It does not determine which mechanism caused every change in these tables, make an antitrust finding against a particular insurer, or calculate a premium increase caused by concentration. The document discusses research connecting concentration and premiums, while recognizing that insurer bargaining savings may not reach consumers.

The most recent common data year is 2024. The report was released in October 2026, but these are not measurements of the 2026 enrollment market or the effect of subsequent policy changes. HHS provided technical comments that GAO incorporated as appropriate; the report issues no new executive recommendations.

Our original contribution is the same-period comparison across the table’s single-issuer, top-three and issuer-count measures, with scope reconciled before drawing conclusions. We reviewed the report’s methods, findings and complete statistical enclosure, and independently checked the arithmetic. We did not independently audit insurer submissions or interview policyholders. The result identifies where aggregate competition indicators point in different directions; it does not turn an enrollment threshold into proof of unlawful conduct.