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Concentration in Health Insurance Markets


About two-thirds of Americans received health insurance through private plans in 2022. People may enroll in these private insurance plans through various markets, including:

  • The individual health insurance market, which offers coverage directly to individuals. The individual exchanges, a subset of the overall individual market, are marketplaces in each state operated by the state or federal government. You can also view overall individual market and individual exchange enrollment data by state..
  • The small-group health insurance market, which offers coverage through small employers.
  • The large-group health insurance market, which offers coverage through large employers.

In this report, we find that private health insurance markets overall were concentrated from 2011 through 2022; most people who enrolled in a private health insurance plan did so with one of a small number of insurance companies. However, the markets for individuals became slightly less concentrated from 2020 through 2022. This concentration in the health insurance market can lead to increases in insurance premiums, which can reduce patients' access to affordable health insurance.

This interactive map provides information on health insurance markets by year and market type. Select a market type (e.g., Small-Group Market) and year (e.g., 2011) to see country-wide data and the associated data table. You can also hover over a state to see more detailed information. Clicking on the play button or moving the slider under the map will show you how the data changes over time for a market type. You can also download the data used in this graphic.



Individual Market

Legend
Largest three issuers hold less than 80% market share
Largest three issuers hold 80-100% market share. Darker blue indicates that this number is closer to 100%.

Source: GAO analysis of data from the Centers for Medicare & Medicaid Services (CMS). | GAO-25-107194


The table below displays data for the selected market and year. Click here to download the data used in this graphic.


State Year No. of Issuers Largest Issuer Largest Issuer Market Share (%) Second Largest Issuer Second Largest Issuer Market Share (%) Third Largest Issuer Third Largest Issuer Market Share (%) Combined Market Share of 3 Largest Issuers (%) Change in 3 Largest Issuer Market Share, 2011-2022 (%)
Alabama 2014 17 BCBS OF ALABAMA GRP 90 UNITEDHEALTH GRP 5 HUMANA GRP 3 98 3
Alaska 2014 12 PREMERA BLUE CROSS GRP 54 OREGON DENTAL GRP 29 ASSURANT INC GRP 9 92 31
Arizona 2014 27 BCBS OF ARIZONA INC 41 HEALTH NET INC GRP 24 UNITEDHEALTH GRP 18 83 -1
Arkansas 2014 21 ARKANSAS BCBS GRP 79 CENTENE CORP GRP 11 CATHOLIC HLTH INITIATIVES GRP 5 94 9
California 2014 33 WELLPOINT INC GRP 35 BLUE SHIELD OF CALIFORNIA GRP 25 KAISER FOUNDATION GRP 23 82 1
Colorado 2014 26 WELLPOINT INC GRP 24 KAISER FOUNDATION GRP 22 HUMANA GRP 11 56 30
Connecticut 2014 17 WELLPOINT INC GRP 36 HIP INS GRP 29 AETNA GRP 20 86 18
Delaware 2014 14 HIGHMARK GRP 72 AETNA GRP 18 UNITEDHEALTH GRP 6 95 18
District of Columbia 2014 16 CAREFIRST INC GRP 77 KAISER FOUNDATION GRP 10 AETNA GRP 8 95 14
Florida 2014 28 BCBS OF FLORIDA INC 40 AETNA GRP 19 HUMANA GRP 16 75 12
Georgia 2014 29 HUMANA GRP 47 WELLPOINT INC GRP 24 AETNA GRP 13 85 4
Hawaii 2014 10 HAWAII MEDICAL SERVS ASSOC 52 KAISER FOUNDATION GRP 47 AMERICAN INTL GRP 1 100 1
Idaho 2014 18 BLUE CROSS OF IDAHO HEALTH SERVS INC 60 REGENCE GRP 21 IHC INC GRP 12 92 -4
Illinois 2014 30 HCSC GRP 78 UNITEDHEALTH GRP 6 HUMANA GRP 5 89 10
Indiana 2014 23 WELLPOINT INC GRP 59 UNITEDHEALTH GRP 13 MDWISE 10 82 16
Iowa 2014 21 WELLMARK GRP 71 AETNA GRP 15 COOPORTUNITY HEALTH 8 93 7
Kansas 2014 24 AETNA GRP 38 BCBS OF KANSAS GRP 34 BCBS OF KC GRP 17 89 20
Kentucky 2014 21 WELLPOINT INC GRP 51 KENTUCKY HEALTH COOP 30 HUMANA GRP 15 96 3
Louisiana 2014 24 LOUISIANA HEALTH SERVS GRP 72 HUMANA GRP 10 AETNA GRP 6 88 14
Maine 2014 15 MAINE COMM HEALTH OPTIONS 55 WELLPOINT INC GRP 32 HEALTHMARKETS GRP 12 99 8
Maryland 2014 19 CAREFIRST INC GRP 76 UNITEDHEALTH GRP 14 KAISER FOUNDATION GRP 3 94 13
Massachusetts 2014 25 BCBS OF MA GRP 30 NEIGHBORHOOD HEALTH PLAN INC 26 TUFTS HEALTH PLAN 17 73 -6
Michigan 2014 31 BCBS OF MICHIGAN GRP 58 UNITEDHEALTH GRP 11 SPECTRUM HEALTH GRP 6 75 14
Minnesota 2014 25 BCBS OF MN GRP 52 PREFERREDONE GRP 25 HEALTHPARTNERS GRP 9 86 -3
Mississippi 2014 21 MISSISSIPPI INS GRP 50 HUMANA GRP 25 UNITEDHEALTH GRP 11 86 9
Missouri 2014 25 AETNA GRP 32 WELLPOINT INC GRP 30 BCBS OF KC GRP 15 77 14
Montana 2014 20 HCSC GRP 56 ASSURANT INC GRP 15 MONTANA HEALTH COOP 14 85 17
Nebraska 2014 25 BCBS OF NEBRASKA 58 COOPORTUNITY HEALTH 19 UNITEDHEALTH GRP 11 88 7
Nevada 2014 19 UNITEDHEALTH GRP 47 WELLPOINT INC GRP 23 NEVADA HEALTH COOP 11 81 -6
New Hampshire 2014 13 WELLPOINT INC GRP 91 ASSURANT INC GRP 7 HEALTHMARKETS GRP 1 99 7
New Jersey 2014 19 BCBS OF NJ GRP 56 INDEPENDENCE HEALTH GRP INC 33 UNITEDHEALTH GRP 6 95 8
New Mexico 2014 18 HCSC GRP 57 PRESBYTERIAN HEALTHCARE SERVS GRP 29 NEW MEXICO HEALTH CONNECTIONS 9 95 -15
New York 2014 32 AMERICAN INTL GRP 15 FREELANCERS HEALTH SERVS CORP 14 WELLPOINT INC GRP 14 43 -1
North Carolina 2014 22 BCBS OF NORTH CAROLINA 84 AETNA GRP 11 ASSURANT INC GRP 1 96 -2
North Dakota 2014 13 NORIDIAN MUTUAL INS CO 83 ASSURANT INC GRP 7 MEDICA GRP 6 96 11
Ohio 2014 32 MEDICAL MUTUAL OF OHIO 38 WELLPOINT INC GRP 28 UNITEDHEALTH GRP 11 76 -30
Oklahoma 2014 23 HCSC GRP 76 UNITEDHEALTH GRP 10 AETNA GRP 5 92 8
Oregon 2014 29 OREGON DENTAL GRP 49 REGENCE GRP 15 KAISER FOUNDATION GRP 9 73 10
Pennsylvania 2014 33 HIGHMARK GRP 41 INDEPENDENCE HEALTH GRP INC 27 AETNA GRP 13 81 8
Rhode Island 2014 11 BCBS OF RHODE ISLAND 94 UNITEDHEALTH GRP 3 NEIGHBORHOOD HLTH PLAN OF RI INC 3 99 0
South Carolina 2014 20 BCBS OF SC GRP 49 CONSUMERS CHOICE HEALTH INS CO 20 AETNA GRP 14 83 18
South Dakota 2014 17 WELLMARK GRP 69 AVERA HEALTH PLANS INC 13 SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA 7 89 12
Tennessee 2014 23 BCBS OF TN INC 62 TRH HEALTH INS CO 20 HUMANA GRP 7 89 -15
Texas 2014 38 HCSC GRP 68 HUMANA GRP 14 CIGNA HEALTH GRP 6 88 -19
Utah 2014 19 IHC INC GRP 46 HUMANA GRP 22 REGENCE GRP 16 85 8
Vermont 2014 10 BCBS OF VT GRP 88 MVP GRP 12 AMERICAN INTL GRP 0 100 1
Virginia 2014 29 WELLPOINT INC GRP 59 CAREFIRST INC GRP 10 AETNA GRP 8 77 -9
Washington 2014 24 PREMERA BLUE CROSS GRP 50 REGENCE GRP 19 GRP HEALTH COOP GRP 16 85 -25
West Virginia 2014 19 HIGHMARK GRP 78 UNITEDHEALTH GRP 11 AETNA GRP 6 94 28
Wisconsin 2014 35 WISCONSIN PHYSICIANS SERVS INS GRP 20 DEAN HEALTH GRP 15 WELLPOINT INC GRP 14 49 -3
Wyoming 2014 16 BCBS OF WYOMING 37 WINHEALTH PARTNERS 27 ASSURANT INC GRP 19 82 40

  • Our analysis includes the 50 states and the District of Columbia.
  • Federal law defines a small employer as having an average of 1 to 50 employees during the preceding calendar year; however, states may apply this definition based on an average of 1 to 100 employees.
  • Small and large employers may offer fully insured group plans (by purchasing coverage from an issuer) or self-funded group plans (by setting aside funds to pay for employee health care). Most small employers purchase fully insured plans, while most large employers self-fund at least some of their employee health benefits. For the small-group and large-group markets, enrollment data are from fully insured plans only.
  • Where multiple issuers in a state shared a parent company, we aggregated the individual issuers to the parent company level. We calculated issuers' market share using covered life-years that issuers reported to Centers for Medicare & Medicaid Services, which measure the average number of lives insured, including dependents, on a pre-specified day of each month of the 12 months in the reporting year. Rather than a point-in-time measurement, this measure accounts for changes in enrollment that occur throughout the year. Market share refers to the ratio of the enrollment for each issuer in a state to the total enrollment in that state.
  • Covered life-years is one of several ways to measure health insurance enrollment, so it may differ from other measures of market size.
  • Names for some issuers have changed over time. For the purposes of this graphic, we have presented the issuer name associated with a given year.
  • We rounded market share values of less than 0.5 percent to zero.