Concentration in Health Insurance Markets
About two-thirds of Americans received health insurance through private plans in 2024. 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 2024; 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 2024. 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) from the tabs and year (e.g., 2011) from the drop down 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
Select a year to view its associated data table.
Source: GAO analysis of data from the Centers for Medicare & Medicaid Services (CMS). | GAO-27-108927
| 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, 2011-2024 (%) |
|---|---|---|---|---|---|---|---|---|---|---|
| Alabama | 2024 | 5 | BCBS OF ALABAMA GRP | 47 | UNITEDHEALTH GRP | 40 | CENTENE CORP GRP | 13 | 100 | 3 |
| Alaska | 2024 | 3 | PREMERA BLUE CROSS GRP | 74 | OREGON DENTAL GRP | 26 | AMERICAN INTL GRP | 0 | 100 | 31 |
| Arizona | 2024 | 9 | CVS HEALTH GRP | 30 | BCBS OF ARIZONA INC | 25 | UNITEDHEALTH GRP | 24 | 79 | 3 |
| Arkansas | 2024 | 5 | ARKANSAS BCBS GRP | 53 | CENTENE CORP GRP | 46 | UNITEDHEALTH GRP | 0 | 100 | 9 |
| California | 2024 | 16 | KAISER FOUNDATION GRP | 33 | BLUE SHIELD OF CALIFORNIA GRP | 32 | ELEVANCE HEALTH INC GRP | 13 | 78 | 0 |
| Colorado | 2024 | 10 | ELEVANCE HEALTH INC GRP | 32 | KAISER FOUNDATION GRP | 24 | CIGNA HEALTH GRP | 20 | 75 | 41 |
| Connecticut | 2024 | 5 | HIP INS GRP | 54 | ELEVANCE HEALTH INC GRP | 46 | AMERICAN INTL GRP | 1 | 100 | 18 |
| Delaware | 2024 | 6 | HIGHMARK GRP | 75 | INDEPENDENCE BLUE CROSS GRP | 11 | CVS HEALTH GRP | 11 | 97 | 15 |
| District of Columbia | 2024 | 4 | CAREFIRST INC GRP | 81 | KAISER FOUNDATION GRP | 18 | AMERICAN INTL GRP | 1 | 100 | 14 |
| Florida | 2024 | 14 | BCBS OF FLORIDA INC | 35 | CENTENE CORP GRP | 24 | OSCAR HEALTH INC GRP | 18 | 77 | 6 |
| Georgia | 2024 | 11 | CENTENE CORP GRP | 40 | OSCAR HEALTH INC GRP | 25 | CVS HEALTH GRP | 10 | 75 | 11 |
| Hawaii | 2024 | 3 | HAWAII MEDICAL SERVS ASSOC | 64 | KAISER FOUNDATION GRP | 35 | AMERICAN INTL GRP | 1 | 100 | 1 |
| Idaho | 2024 | 9 | IHC INC GRP | 32 | REGENCE GRP | 26 | GEMSTONE HOLDINGS GRP | 24 | 82 | -11 |
| Illinois | 2024 | 15 | HCSC GRP | 57 | CENTENE CORP GRP | 12 | CVS HEALTH GRP | 11 | 80 | 1 |
| Indiana | 2024 | 9 | CENTENE CORP GRP | 36 | ELEVANCE HEALTH INC GRP | 30 | CARESOURCE MANAGEMENT GRP | 27 | 93 | 14 |
| Iowa | 2024 | 6 | WELLMARK GRP | 75 | OSCAR HEALTH INC GRP | 17 | MEDICA GRP | 7 | 99 | 8 |
| Kansas | 2024 | 11 | CENTENE CORP GRP | 42 | BCBS OF KANSAS GRP | 17 | UNITEDHEALTH GRP | 16 | 76 | -1 |
| Kentucky | 2024 | 11 | ELEVANCE HEALTH INC GRP | 49 | WELLCARE MANAGEMENT GRP | 25 | CARESOURCE MANAGEMENT GRP | 23 | 98 | 2 |
| Louisiana | 2024 | 8 | LOUISIANA HEALTH SERVS GRP | 49 | CENTENE CORP GRP | 26 | UNITEDHEALTH GRP | 19 | 94 | 10 |
| Maine | 2024 | 6 | ELEVANCE HEALTH INC GRP | 43 | MAINE COMM HEALTH OPTIONS | 31 | HARVARD PILGRIM HTH CARE GRP | 25 | 99 | 7 |
| Maryland | 2024 | 6 | CAREFIRST INC GRP | 57 | UNITEDHEALTH GRP | 22 | KAISER FOUNDATION GRP | 20 | 99 | 12 |
| Massachusetts | 2024 | 11 | TUFTS HEALTH PLAN | 49 | BOSTON MEDICAL CENTER HEALTH PLAN INC | 25 | HARVARD PILGRIM HTH CARE GRP | 7 | 81 | -8 |
| Michigan | 2024 | 10 | COREWELL HEALTH GRP | 31 | BCBS OF MICHIGAN GRP | 30 | CENTENE CORP GRP | 20 | 82 | 7 |
| Minnesota | 2024 | 10 | BCBS OF MN GRP | 31 | UCARE GRP | 27 | HEALTHPARTNERS GRP | 27 | 85 | 0 |
| Mississippi | 2024 | 9 | CENTENE CORP GRP | 61 | CIGNA HEALTH GRP | 17 | MISSISSIPPI INS GRP | 9 | 87 | 5 |
| Missouri | 2024 | 12 | CENTENE CORP GRP | 37 | ELEVANCE HEALTH INC GRP | 29 | UNITEDHEALTH GRP | 11 | 77 | 11 |
| Montana | 2024 | 4 | HCSC GRP | 49 | MONTANA HEALTH COOP | 37 | PACIFICSOURCE HEALTH PLAN GRP | 14 | 100 | 17 |
| Nebraska | 2024 | 8 | CENTENE CORP GRP | 56 | MEDICA GRP | 28 | BCBS OF NEBRASKA | 14 | 98 | 11 |
| Nevada | 2024 | 9 | UNITEDHEALTH GRP | 46 | ELEVANCE HEALTH INC GRP | 18 | CENTENE CORP GRP | 16 | 80 | -4 |
| New Hampshire | 2024 | 4 | ELEVANCE HEALTH INC GRP | 73 | CENTENE CORP GRP | 22 | HARVARD PILGRIM HTH CARE GRP | 5 | 100 | 7 |
| New Jersey | 2024 | 9 | BCBS OF NJ GRP | 50 | INDEPENDENCE BLUE CROSS GRP | 22 | CVS HEALTH GRP | 18 | 91 | 1 |
| New Mexico | 2024 | 7 | HCSC GRP | 48 | PRESBYTERIAN HEALTHCARE SERVS GRP | 26 | MOLINA HEALTHCARE INC GRP | 11 | 85 | -5 |
| New York | 2024 | 18 | NEW YORK STATE CATHOLIC HEALTH PLAN INC | 30 | HEALTHFIRST INC GRP | 15 | AMERICAN INTL GRP | 14 | 59 | 5 |
| North Carolina | 2024 | 11 | BCBS OF NC GRP | 43 | CVS HEALTH GRP | 34 | CENTENE CORP GRP | 13 | 90 | 0 |
| North Dakota | 2024 | 5 | BCBS OF NORTH DAKOTA | 59 | SANFORD HLTH GRP | 38 | MEDICA GRP | 4 | 100 | 11 |
| Ohio | 2024 | 13 | ELEVANCE HEALTH INC GRP | 19 | CENTENE CORP GRP | 16 | OSCAR HEALTH INC GRP | 13 | 49 | -39 |
| Oklahoma | 2024 | 10 | HCSC GRP | 57 | CENTENE CORP GRP | 23 | COMMUNITYCARE GRP | 6 | 86 | 8 |
| Oregon | 2024 | 7 | PROVIDENCE HLTH GRP | 26 | REGENCE GRP | 21 | KAISER FOUNDATION GRP | 20 | 68 | 4 |
| Pennsylvania | 2024 | 14 | INDEPENDENCE BLUE CROSS GRP | 29 | HIGHMARK GRP | 26 | UPMC HEALTH SYSTEM GRP | 21 | 76 | 6 |
| Rhode Island | 2024 | 4 | NEIGHBORHOOD HLTH PLAN OF RI INC | 65 | BCBS OF RHODE ISLAND | 35 | AMERICAN INTL GRP | 0 | 100 | 0 |
| South Carolina | 2024 | 8 | BCBS OF SC GRP | 51 | CENTENE CORP GRP | 39 | MOLINA HEALTHCARE INC GRP | 5 | 95 | 19 |
| South Dakota | 2024 | 6 | SANFORD HLTH GRP | 40 | WELLMARK GRP | 31 | AVERA HEALTH PLANS INC | 29 | 100 | 13 |
| Tennessee | 2024 | 9 | CENTENE CORP GRP | 46 | BCBS OF TN INC | 20 | CIGNA HEALTH GRP | 15 | 80 | 0 |
| Texas | 2024 | 18 | HCSC GRP | 40 | UNITEDHEALTH GRP | 18 | CENTENE CORP GRP | 15 | 74 | 0 |
| Utah | 2024 | 10 | IHC INC GRP | 70 | CVS HEALTH GRP | 19 | REGENCE GRP | 6 | 95 | 11 |
| Vermont | 2024 | 3 | BLUE CARE NETWORK OF MICHIGAN | 68 | MVP GRP | 32 | AMERICAN INTL GRP | 0 | 100 | 1 |
| Virginia | 2024 | 10 | ELEVANCE HEALTH INC GRP | 38 | SENTARA HEALTH MANAGEMENT GRP | 17 | CVS HEALTH GRP | 13 | 68 | -21 |
| Washington | 2024 | 13 | CENTENE CORP GRP | 29 | KAISER FOUNDATION GRP | 16 | MOLINA HEALTHCARE INC GRP | 15 | 60 | -38 |
| West Virginia | 2024 | 6 | HIGHMARK GRP | 57 | CARESOURCE MANAGEMENT GRP | 42 | UNITEDHEALTH GRP | 1 | 100 | 28 |
| Wisconsin | 2024 | 16 | MEDICA GRP | 23 | ELEVANCE HEALTH INC GRP | 22 | COMMON GROUND HEALTHCARE COOP | 16 | 61 | 4 |
| Wyoming | 2024 | 5 | BCBS OF WYOMING | 69 | MONTANA HEALTH COOP | 31 | UNITEDHEALTH GRP | 0 | 100 | 40 |
- Our analysis includes the 50 states and the District of Columbia.
- Federal law defines a small employer as having an average of one to 50 employees during the preceding calendar year; however, states may apply this definition based on an average of one 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.