The vast majority of Medicare Advantage markets are highly concentrated, according to the American Medical Association's annual Competition in Health Insurance report.
In 91% of MA markets, one insurer controls at least 30% of the market, and in 30% of markets, the largest insurer controls more than 50% of the market. UnitedHealth Group is the largest Medicare Advantage insurer overall, with a national market share of 29%.
The largest Medicare Advantage insurer by state, by market share:
Alabama
UnitedHealth: 43%
Arizona
UnitedHealth: 48%
Arkansas
UnitedHealth: 42%
California
Kaiser: 43%
Colorado
UnitedHealth: 50%
Connecticut
UnitedHealth: 37%
Delaware
UnitedHealth: 37%
Florida
Humana: 31%
Georgia
UnitedHealth: 34%
Hawaii
UnitedHealth: 28%
Idaho
UnitedHealth: 33%
Illinois
Humana: 29%
Indiana
UnitedHealth: 38%
Iowa
UnitedHealth: 43%
Kansas
UnitedHealth: 39%
Kentucky
Humana: 43%
Louisiana
Humana: 48%
Maine
Martin's Point: 30%
Maryland
Kasier: 33%
Massachusetts
UnitedHealth: 26%
Michigan
BCBS: 43%
Minnesota
BCBS: 34%
Mississippi
Humana: 49%
Missouri
UnitedHealth: 51%
Montana
Humana: 63%
Nebraska
UnitedHealth: 57%
Nevada
UnitedHealth: 38%
New Hampshire
UnitedHealth: 38%
New Jersey
Aetna: 35%
New Mexico
Presbyterian: 27%
New York
UnitedHealth: 24%
North Carolina
Humana: 39%
North Dakota
Medica: 51%
Ohio
Elevance: 25%
Oklahoma
UnitedHealth: 51%
Oregon
UnitedHealth: 27%
Pennsylvania
Aetna: 27%
Rhode Island
BCBS: 58%
South Carolina
Humana: 38%
South Dakota
Medica: 53%
Tennessee
UnitedHealth: 28%
Texas
UnitedHealth: 50%
Utah
UnitedHealth: 53%
Vermont
UnitedHealth: 51%
Virginia
Humana: 32%
Washington
UnitedHealth: 36%
West Virginia
Humana: 55%
Wisconsin
UnitedHealth: 46%
Wyoming
UnitedHealth: 79%