Medicare Advantage (MA) markets are highly concentrated across the country, according to a new study from KFF.
As of 2024, 90% of Medicare beneficiaries live in a county where those enrolled in MA had plans sponsored by just one or two insurers, according to the report.
The researchers found that 79% of counties were highly concentrated, and 18% were very highly concentrated. Fewer than 1% of counties were moderately concentrated, and virtually no counties were considered highly competitive marketplaces, the study says.
The majority (89%) of enrollees live in a county that is highly concentrated, while 4% are in very highly concentrated markets, according to the report. The study found 28.9 million of the total 32.3 million enrollees lived in a highly concentrated county last year.
UnitedHealthcare and Humana are the two largest players in MA by enrollment, and they had the highest enrollment in two-thirds of counties for 2024, according to the study. These counties accounted for 59% of total MA sign-ups.
UnitedHealth in particular is the dominant player in 41% of highly concentrated markets, the largest share for any individual insurer. It was the leader in half of very highly concentrated markets, also the largest share.
“UnitedHealthcare and Humana have consistently been the two largest insurers in the Medicare Advantage market, and comprised nearly half (47%) of all Medicare Advantage enrollment across the country in 2024,” the researchers said.
In 44% of counties, a single insurer controlled at least half of MA enrollment. In half of those counties, that insurer was UnitedHealthcare. Humana, meanwhile, claimed at least half of all MA enrollees in 10% of counties.
This level of concentration extended to some large markets, including Dallas County, Texas; Salt Lake County, Utah; and Milwaukee County, Wisconsin, KFF found. However, rural counties were more likely than urban counties to be highly concentrated, according to the report.
Thirty-nine percent of rural counties were highly concentrated in 2024, as were 15% of rural-adjacent counties and 6% of urban markets.
The researchers note that policymakers have not put a focus on competition in MA markets for some time, with the latest action in the space when the Department of Justice blocked the merger between Aetna and Humana in 2017, citing competition in MA.
Recent conversation on consolidation has generally focused on provider markets, according to the report.