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 Exchange 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 | Weighted Avg 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 (%) | Weighted Avg Market Share of Largest Issuer Across Rating Areas (%) | Change in Largest Issuer Market Share across Rating Areas, 2015-2022 (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Alabama | 2018 | 2 | 1.2 | BCBS OF ALABAMA GRP | 99 | BRIGHT HEALTH GRP | 1 | -- | -- | 100 | 99 | 12 |
| Alaska | 2018 | 1 | 1 | PREMERA BLUE CROSS GRP | 100 | -- | -- | -- | -- | 100 | 100 | 24 |
| Arizona | 2018 | 2 | 1.2 | CENTENE CORP GRP | 74 | BCBS OF ARIZONA INC | 26 | -- | -- | 100 | 99 | 11 |
| Arkansas | 2018 | 3 | 3 | ARKANSAS BCBS GRP | 61 | CENTENE CORP GRP | 38 | CATHOLIC HLTH INITIATIVES GRP | 2 | 100 | 61 | -43 |
| California | 2018 | 11 | 5.2 | KAISER FOUNDATION GRP | 33 | BLUE SHIELD OF CALIFORNIA GRP | 33 | CENTENE CORP GRP | 14 | 80 | 47 | 7 |
| Colorado | 2018 | 7 | 5 | KAISER FOUNDATION GRP | 43 | WELLPOINT INC GRP | 26 | CIGNA HEALTH GRP | 17 | 85 | 56 | -26 |
| Connecticut | 2018 | 2 | 2 | HIP INS GRP | 74 | WELLPOINT INC GRP | 26 | -- | -- | 100 | 79 | 38 |
| Delaware | 2018 | 1 | 1 | HIGHMARK GRP | 100 | -- | -- | -- | -- | 100 | 100 | 9 |
| District of Columbia | 2018 | 2 | 2 | CAREFIRST INC GRP | 80 | KAISER FOUNDATION GRP | 20 | -- | -- | 100 | 80 | 0 |
| Florida | 2018 | 4 | 2.5 | BCBS OF FLORIDA INC | 68 | CENTENE CORP GRP | 28 | MOLINA HEALTHCARE INC GRP | 3 | 99 | 70 | -16 |
| Georgia | 2018 | 4 | 2.4 | CENTENE CORP GRP | 52 | KAISER FOUNDATION GRP | 21 | WELLPOINT INC GRP | 16 | 90 | 76 | -14 |
| Hawaii | 2018 | 2 | 2 | HAWAII MEDICAL SERVS ASSOC | 51 | KAISER FOUNDATION GRP | 49 | -- | -- | 100 | 51 | -- |
| Idaho | 2018 | 4 | 4 | BLUE CROSS OF IDAHO HEALTH SERVS INC | 48 | MONTANA HEALTH COOP | 26 | IHC INC GRP | 26 | 100 | 52 | -4 |
| Illinois | 2018 | 4 | 2.4 | HCSC GRP | 73 | CARLE HOLDING CO GRP | 10 | CENTENE CORP GRP | 9 | 92 | 75 | -24 |
| Indiana | 2018 | 2 | 1.9 | CARESOURCE MANAGEMENT GRP | 52 | CENTENE CORP GRP | 48 | -- | -- | 100 | 69 | 24 |
| Iowa | 2018 | 1 | 1 | MEDICA GRP | 100 | -- | -- | -- | -- | 100 | 100 | -33 |
| Kansas | 2018 | 3 | 2.3 | BCBS OF KANSAS GRP | 63 | CENTENE CORP GRP | 23 | MEDICA GRP | 14 | 100 | 84 | -6 |
| Kentucky | 2018 | 2 | 1.6 | CARESOURCE MANAGEMENT GRP | 65 | WELLPOINT INC GRP | 35 | -- | -- | 100 | 90 | 10 |
| Louisiana | 2018 | 2 | 2 | LOUISIANA HEALTH SERVS GRP | 90 | VANTAGE HEALTH PLAN INC | 10 | -- | -- | 100 | 90 | 61 |
| Maine | 2018 | 2 | 2 | MAINE COMM HEALTH OPTIONS | 60 | HARVARD PILGRIM HTH CARE GRP | 40 | -- | -- | 100 | 61 | -46 |
| Maryland | 2018 | 2 | 2 | CAREFIRST INC GRP | 54 | KAISER FOUNDATION GRP | 46 | -- | -- | 100 | 65 | -18 |
| Massachusetts | 2018 | 7 | 6.3 | TUFTS HEALTH PLAN | 49 | BOSTON MEDICAL CENTER HEALTH PLAN INC | 35 | ALLWAYS HEALTH PARTNERS INC | 8 | 92 | 50 | 28 |
| Michigan | 2018 | 7 | 5.1 | BCBS OF MICHIGAN GRP | 62 | SPECTRUM HEALTH GRP | 17 | MOLINA HEALTHCARE INC GRP | 7 | 86 | 62 | -23 |
| Minnesota | 2018 | 4 | 3.3 | UCARE MINNESOTA | 31 | MEDICA GRP | 29 | HEALTHPARTNERS GRP | 26 | 86 | 55 | -- |
| Mississippi | 2018 | 1 | 1 | CENTENE CORP GRP | 100 | -- | -- | -- | -- | 100 | 100 | 44 |
| Missouri | 2018 | 3 | 1.9 | CIGNA HEALTH GRP | 48 | CENTENE CORP GRP | 30 | WELLPOINT INC GRP | 22 | 100 | 77 | -12 |
| Montana | 2018 | 3 | 3 | MONTANA HEALTH COOP | 50 | HCSC GRP | 29 | PACIFICSOURCE HEALTH PLAN GRP | 21 | 100 | 50 | -8 |
| Nebraska | 2018 | 1 | 1 | MEDICA GRP | 100 | -- | -- | -- | -- | 100 | 100 | -20 |
| Nevada | 2018 | 2 | 1.9 | UNITEDHEALTH GRP | 64 | CENTENE CORP GRP | 36 | -- | -- | 100 | 72 | 6 |
| New Hampshire | 2018 | 3 | 3 | WELLPOINT INC GRP | 81 | CENTENE CORP GRP | 11 | HARVARD PILGRIM HTH CARE GRP | 8 | 100 | 81 | -19 |
| New Jersey | 2018 | 3 | 3 | BCBS OF NJ GRP | 55 | INDEPENDENCE HEALTH GRP INC | 42 | MULBERRY HLTH GRP | 3 | 100 | 55 | 9 |
| New Mexico | 2018 | 4 | 4 | MOLINA HEALTHCARE INC GRP | 58 | NEW MEXICO HEALTH CONNECTIONS | 30 | HCSC GRP | 6 | 95 | 58 | -3 |
| New York | 2018 | 13 | 7.5 | NEW YORK STATE CATHOLIC HEALTH PLAN INC | 43 | HEALTHFIRST PHSP INC | 12 | HIP INS GRP | 8 | 62 | 44 | 90 |
| North Carolina | 2018 | 2 | 1.2 | BCBS OF NORTH CAROLINA | 96 | CIGNA HEALTH GRP | 4 | -- | -- | 100 | 96 | -11 |
| North Dakota | 2018 | 2 | 1.9 | NORIDIAN MUTUAL INS CO | 80 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 20 | -- | -- | 100 | 89 | -15 |
| Ohio | 2018 | 8 | 4.2 | CARESOURCE MANAGEMENT GRP | 41 | MEDICAL MUTUAL OF OHIO | 27 | CENTENE CORP GRP | 12 | 79 | 49 | -13 |
| Oklahoma | 2018 | 1 | 1 | HCSC GRP | 100 | -- | -- | -- | -- | 100 | 100 | -26 |
| Oregon | 2018 | 5 | 4 | PROVIDENCE HEALTH PLAN | 48 | KAISER FOUNDATION GRP | 24 | OREGON DENTAL GRP | 21 | 93 | 54 | 2 |
| Pennsylvania | 2018 | 6 | 2.2 | INDEPENDENCE HEALTH GRP INC | 41 | UPMC HEALTH OPTIONS INC | 27 | GEISINGER INS GRP | 16 | 84 | 82 | -4 |
| Rhode Island | 2018 | 2 | 2 | NEIGHBORHOOD HLTH PLAN OF RI INC | 72 | BCBS OF RHODE ISLAND | 28 | -- | -- | 100 | 72 | 54 |
| South Carolina | 2018 | 1 | 1 | BCBS OF SC GRP | 100 | -- | -- | -- | -- | 100 | 100 | 20 |
| South Dakota | 2018 | 2 | 2 | AVERA HEALTH PLANS INC | 51 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 49 | -- | -- | 100 | 66 | 3 |
| Tennessee | 2018 | 3 | 1.3 | BCBS OF TN INC | 55 | CIGNA HEALTH GRP | 35 | MULBERRY HLTH GRP | 10 | 100 | 87 | -46 |
| Texas | 2018 | 8 | 3.6 | HCSC GRP | 27 | MOLINA HEALTHCARE INC GRP | 25 | CENTENE CORP GRP | 21 | 73 | 52 | -44 |
| Utah | 2018 | 2 | 2 | IHC INC GRP | 88 | UNIVERSITY OF UTAH HEALTH INS PLANS | 12 | -- | -- | 100 | 88 | 51 |
| Vermont | 2018 | 2 | 2 | BCBS OF VT GRP | 61 | MVP GRP | 39 | -- | -- | 100 | 61 | -44 |
| Virginia | 2018 | 6 | 3.3 | CIGNA HEALTH GRP | 29 | KAISER FOUNDATION GRP | 25 | SENTARA HEALTH MANAGEMENT GRP | 19 | 73 | 79 | 9 |
| Washington | 2018 | 5 | 3.9 | KAISER FOUNDATION GRP | 39 | CENTENE CORP GRP | 26 | PREMERA BLUE CROSS GRP | 22 | 88 | 42 | -33 |
| West Virginia | 2018 | 2 | 1.8 | HIGHMARK GRP | 68 | CARESOURCE WEST VIRGINIA CO | 32 | -- | -- | 100 | 74 | -33 |
| Wisconsin | 2018 | 11 | 3.7 | COMMON GROUND HEALTHCARE COOP | 28 | SECURITY HEALTH PLAN OF WISCONSIN INC | 16 | DEAN HEALTH GRP | 16 | 59 | 60 | 6 |
| Wyoming | 2018 | 1 | 1 | BCBS OF WYOMING | 100 | -- | -- | -- | -- | 100 | 100 | 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.
- 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 or states. This measure is calculated as the average number of lives insured each month in the reporting year. Rather than a point-in-time measurement, this measure accounts for changes in enrollment that occur throughout the year.
- This table presents two calculations of individual exchange market share, one unweighted and one weighted. "Market share" refers to the unweighted ratio of the enrollment for each issuer in a state to the total enrollment in that state. "Weighted average market share across rating areas" refers to average market share of an issuer across a state's rating areas, which are geographic areas established by states and used, in part, by issuers to set premium rates, weighted by the number of covered life-years in each rating area.
- 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.
- Hawaii and Minnesota are not included in this figure for 2015 because we were unable to obtain data for that year. The remaining 49 states, including the District of Columbia, are included in 2015, and Hawaii and Minnesota are included for later years.