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 Exchange 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 | 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, 2015-2024 (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Alabama | 2024 | 3 | 2.9 | BCBS OF ALABAMA GRP | 44 | UNITEDHEALTH GRP | 42 | CENTENE CORP GRP | 14 | 100 | 55 | -32 |
| Alaska | 2024 | 2 | 2 | PREMERA BLUE CROSS GRP | 74 | OREGON DENTAL GRP | 26 | -- | -- | 100 | 74 | 4 |
| Arizona | 2024 | 8 | 7 | CVS HEALTH GRP | 32 | UNITEDHEALTH GRP | 24 | BCBS OF ARIZONA INC | 22 | 77 | 42 | 8 |
| Arkansas | 2024 | 4 | 4 | CENTENE CORP GRP | 56 | ARKANSAS BCBS GRP | 41 | CENTENE CORP GRP | 1 | 99 | 57 | -40 |
| California | 2024 | 13 | 5.4 | BLUE SHIELD OF CALIFORNIA GRP | 33 | KAISER FOUNDATION GRP | 33 | ELEVANCE HEALTH INC GRP | 12 | 77 | 46 | 7 |
| Colorado | 2024 | 6 | 5.2 | ELEVANCE HEALTH INC GRP | 32 | KAISER FOUNDATION GRP | 24 | CIGNA HEALTH GRP | 20 | 75 | 41 | -16 |
| Connecticut | 2024 | 2 | 2 | HIP INS GRP | 54 | ELEVANCE HEALTH INC GRP | 46 | -- | -- | 100 | 62 | 13 |
| Delaware | 2024 | 4 | 4 | HIGHMARK GRP | 74 | INDEPENDENCE BLUE CROSS GRP | 12 | CVS HEALTH GRP | 11 | 98 | 74 | -19 |
| District of Columbia | 2024 | 2 | 2 | CAREFIRST INC GRP | 80 | KAISER FOUNDATION GRP | 20 | -- | -- | 100 | 80 | 0 |
| Florida | 2024 | 10 | 7.4 | BCBS OF FLORIDA INC | 33 | CENTENE CORP GRP | 25 | OSCAR INS CO OF FLORIDA | 19 | 77 | 44 | -25 |
| Georgia | 2024 | 9 | 7.2 | CENTENE CORP GRP | 41 | OSCAR HEALTH PLAN OF GEORGIA | 26 | CVS HEALTH GRP | 10 | 76 | 53 | -13 |
| Hawaii | 2024 | 2 | 2 | HAWAII MEDICAL SERVS ASSOC | 61 | KAISER FOUNDATION GRP | 39 | -- | -- | 100 | 61 | -- |
| Idaho | 2024 | 8 | 7.2 | IHC INC GRP | 34 | REGENCE GRP | 25 | BLUE CROSS OF IDAHO HEALTH SERVS INC | 21 | 81 | 46 | -25 |
| Illinois | 2024 | 11 | 5.8 | HCSC GRP | 52 | CENTENE CORP GRP | 14 | CVS HEALTH GRP | 12 | 79 | 54 | -31 |
| Indiana | 2024 | 6 | 4.3 | CENTENE CORP GRP | 37 | ELEVANCE HEALTH INC GRP | 30 | CARESOURCE MANAGEMENT GRP | 27 | 94 | 51 | 7 |
| Iowa | 2024 | 3 | 3 | WELLMARK GRP | 70 | OSCAR INS CO | 21 | MEDICA GRP | 9 | 100 | 70 | -28 |
| Kansas | 2024 | 8 | 5.3 | CENTENE CORP GRP | 46 | UNITEDHEALTH GRP | 18 | CVS HEALTH GRP | 14 | 78 | 53 | -20 |
| Kentucky | 2024 | 4 | 3.6 | ELEVANCE HEALTH INC GRP | 42 | WELLCARE MANAGEMENT GRP | 29 | CARESOURCE MANAGEMENT GRP | 27 | 98 | 47 | -27 |
| Louisiana | 2024 | 4 | 2.6 | LOUISIANA HEALTH SERVS GRP | 43 | AMBETTER HEALTH OF LOUISIANA INC | 29 | UNITEDHEALTH GRP | 21 | 93 | 52 | -2 |
| Maine | 2024 | 4 | 3.7 | ELEVANCE HEALTH INC GRP | 43 | MAINE COMM HEALTH OPTIONS | 31 | HARVARD PILGRIM HTH CARE GRP | 25 | 99 | 43 | -47 |
| Maryland | 2024 | 4 | 4 | CAREFIRST INC GRP | 55 | UNITEDHEALTH GRP | 23 | KAISER FOUNDATION GRP | 21 | 99 | 55 | -29 |
| Massachusetts | 2024 | 8 | 6.9 | TUFTS HEALTH PLAN | 49 | BOSTON MEDICAL CENTER HEALTH PLAN INC | 25 | HARVARD PILGRIM HTH CARE GRP | 7 | 81 | 49 | 17 |
| Michigan | 2024 | 8 | 5.7 | COREWELL HEALTH GRP | 31 | BCBS OF MICHIGAN GRP | 27 | MERIDIAN HEALTH PLAN OF MICHIGAN INC | 23 | 82 | 47 | -30 |
| Minnesota | 2024 | 5 | 4.1 | BCBS OF MN GRP | 31 | HEALTHPARTNERS GRP | 27 | UCARE MINNESOTA | 27 | 86 | 44 | -- |
| Mississippi | 2024 | 5 | 4.8 | CENTENE CORP GRP | 68 | CIGNA HEALTH GRP | 19 | MOLINA HEALTHCARE INC GRP | 9 | 96 | 75 | 33 |
| Missouri | 2024 | 8 | 5.4 | CENTENE CORP GRP | 39 | ELEVANCE HEALTH INC GRP | 27 | UNITEDHEALTH GRP | 11 | 77 | 52 | -22 |
| Montana | 2024 | 3 | 3 | HCSC GRP | 48 | MONTANA HEALTH COOP | 40 | PACIFICSOURCE HEALTH PLAN GRP | 13 | 100 | 50 | 6 |
| Nebraska | 2024 | 4 | 4 | CENTENE CORP GRP | 58 | MEDICA GRP | 27 | BCBS OF NEBRASKA | 14 | 99 | 58 | -4 |
| Nevada | 2024 | 8 | 6.7 | UNITEDHEALTH GRP | 46 | ELEVANCE HEALTH INC GRP | 18 | SILVERSUMMIT HEALTHPLAN INC | 16 | 80 | 54 | 13 |
| New Hampshire | 2024 | 3 | 3 | ELEVANCE HEALTH INC GRP | 70 | CENTENE CORP GRP | 26 | HARVARD PILGRIM HTH CARE GRP | 4 | 100 | 70 | 17 |
| New Jersey | 2024 | 6 | 6 | BCBS OF NJ GRP | 51 | INDEPENDENCE BLUE CROSS GRP | 23 | CVS HEALTH GRP | 18 | 91 | 51 | -6 |
| New Mexico | 2024 | 5 | 5 | HCSC GRP | 48 | PRESBYTERIAN HEALTHCARE SERVS GRP | 26 | MOLINA HEALTHCARE INC GRP | 11 | 85 | 53 | 24 |
| New York | 2024 | 14 | 8 | NEW YORK STATE CATHOLIC HEALTH PLAN INC | 36 | HEALTHFIRST PHSP INC | 18 | LIFETIME HEALTHCARE GRP | 9 | 63 | 41 | 67 |
| North Carolina | 2024 | 9 | 6 | BCBS OF NORTH CAROLINA | 40 | CVS HEALTH GRP | 36 | AMBETTER OF NORTH CAROLINA INC | 14 | 90 | 56 | -19 |
| North Dakota | 2024 | 3 | 2.8 | BCBS OF NORTH DAKOTA | 49 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 46 | MEDICA GRP | 5 | 100 | 64 | -11 |
| Ohio | 2024 | 11 | 7.4 | CENTENE CORP GRP | 18 | ELEVANCE HEALTH INC GRP | 18 | MOLINA HEALTHCARE INC GRP | 14 | 50 | 39 | -6 |
| Oklahoma | 2024 | 7 | 5.5 | HCSC GRP | 56 | CENTENE CORP GRP | 24 | COMMUNITYCARE GRP | 6 | 86 | 57 | -42 |
| Oregon | 2024 | 6 | 5.8 | PROVIDENCE HEALTH PLAN | 25 | REGENCE GRP | 22 | KAISER FOUNDATION GRP | 20 | 68 | 43 | 2 |
| Pennsylvania | 2024 | 10 | 4.8 | INDEPENDENCE BLUE CROSS GRP | 30 | HIGHMARK GRP | 26 | UPMC HEALTH SYSTEM GRP | 21 | 77 | 66 | -11 |
| Rhode Island | 2024 | 2 | 2 | 0 | 65 | BCBS OF RHODE ISLAND | 35 | -- | -- | 100 | 65 | 30 |
| South Carolina | 2024 | 6 | 4.3 | BCBS OF SC GRP | 48 | ABSOLUTE TOTAL CARE INC | 42 | MOLINA HEALTHCARE INC GRP | 5 | 95 | 54 | -9 |
| South Dakota | 2024 | 3 | 2.6 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 46 | AVERA HEALTH PLANS INC | 33 | WELLMARK GRP | 21 | 100 | 67 | 11 |
| Tennessee | 2024 | 6 | 4.7 | CENTENE CORP GRP | 48 | BCBS OF TN INC | 19 | CIGNA HEALTH GRP | 15 | 83 | 49 | -37 |
| Texas | 2024 | 15 | 7.6 | HCSC GRP | 38 | UNITEDHEALTH GRP | 19 | CENTENE CORP GRP | 16 | 74 | 44 | -36 |
| Utah | 2024 | 8 | 6.8 | IHC INC GRP | 70 | CVS HEALTH GRP | 20 | REGENCE GRP | 5 | 95 | 70 | 28 |
| Vermont | 2024 | 2 | 2 | BLUE CARE NETWORK OF MICHIGAN | 68 | MVP GRP | 32 | -- | -- | 100 | 68 | -25 |
| Virginia | 2024 | 8 | 5.8 | ELEVANCE HEALTH INC GRP | 38 | SENTARA HEALTH MANAGEMENT GRP | 18 | CIGNA HEALTH GRP | 13 | 69 | 44 | -14 |
| Washington | 2024 | 10 | 8.2 | CENTENE CORP GRP | 29 | KAISER FOUNDATION GRP | 16 | MOLINA HEALTHCARE INC GRP | 14 | 60 | 32 | -33 |
| West Virginia | 2024 | 2 | 2 | HIGHMARK GRP | 57 | CARESOURCE MANAGEMENT GRP | 43 | -- | -- | 100 | 64 | -36 |
| Wisconsin | 2024 | 14 | 7.2 | ELEVANCE HEALTH INC GRP | 24 | COMMON GROUND HEALTHCARE COOP | 19 | MEDICA GRP | 11 | 54 | 51 | -2 |
| Wyoming | 2024 | 2 | 2 | BCBS OF WYOMING | 68 | MONTANA HEALTH COOP | 32 | -- | -- | 100 | 68 | 11 |
- 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.
- 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—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.
- 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.