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 | 2015 | 3 | 2.3 | BCBS OF ALABAMA GRP | 81 | UNITEDHEALTH GRP | 15 | HUMANA GRP | 4 | 100 | 81 | 12 |
| Alaska | 2015 | 2 | 2 | OREGON DENTAL GRP | 71 | PREMERA BLUE CROSS GRP | 29 | -- | -- | 100 | 71 | 24 |
| Arizona | 2015 | 12 | 11 | CENTENE CORP GRP | 32 | COMPASS COOP HEALTH PLAN INC | 28 | BCBS OF ARIZONA INC | 20 | 81 | 39 | 11 |
| Arkansas | 2015 | 3 | 3 | ARKANSAS BCBS GRP | 94 | CENTENE CORP GRP | 4 | CATHOLIC HLTH INITIATIVES GRP | 1 | 100 | 94 | -43 |
| California | 2015 | 10 | 4.8 | WELLPOINT INC GRP | 28 | BLUE SHIELD OF CALIFORNIA GRP | 27 | KAISER FOUNDATION GRP | 23 | 78 | 43 | 7 |
| Colorado | 2015 | 10 | 8.2 | COLORADO HEALTH INS COOP INC | 43 | KAISER FOUNDATION GRP | 29 | ROCKY MOUNTAIN HEALTH GRP | 13 | 86 | 49 | -26 |
| Connecticut | 2015 | 4 | 4 | HIP INS GRP | 43 | WELLPOINT INC GRP | 39 | HEALTHYCT INC | 16 | 98 | 55 | 38 |
| Delaware | 2015 | 2 | 2 | HIGHMARK GRP | 92 | AETNA GRP | 8 | -- | -- | 100 | 92 | 9 |
| District of Columbia | 2015 | 3 | 3 | CAREFIRST INC GRP | 81 | KAISER FOUNDATION GRP | 16 | AETNA GRP | 3 | 100 | 81 | 0 |
| Florida | 2015 | 11 | 6.1 | BCBS OF FLORIDA INC | 26 | HUMANA GRP | 21 | AETNA GRP | 19 | 66 | 59 | -16 |
| Georgia | 2015 | 9 | 7.8 | HUMANA GRP | 57 | AETNA GRP | 14 | WELLPOINT INC GRP | 14 | 85 | 61 | -14 |
| Idaho | 2015 | 5 | 5 | BLUE CROSS OF IDAHO HEALTH SERVS INC | 57 | IHC INC GRP | 24 | MONTANA HEALTH COOP | 18 | 99 | 61 | -4 |
| Illinois | 2015 | 8 | 5.7 | HCSC GRP | 77 | LAND OF LINCOLN MUTUAL HEALTH INS CO | 11 | AETNA GRP | 6 | 94 | 78 | -24 |
| Indiana | 2015 | 9 | 6.9 | WELLPOINT INC GRP | 47 | UNITEDHEALTH GRP | 16 | MDWISE MARKETPLACE INC | 11 | 75 | 48 | 24 |
| Iowa | 2015 | 4 | 2.6 | AETNA GRP | 97 | COOPORTUNITY HEALTH | 2 | AVERA HEALTH PLANS INC | 0 | 100 | 97 | -33 |
| Kansas | 2015 | 3 | 2.4 | AETNA GRP | 56 | BCBS OF KANSAS GRP | 38 | BCBS OF KC GRP | 6 | 100 | 66 | -6 |
| Kentucky | 2015 | 5 | 4.8 | KENTUCKY HEALTH COOP | 64 | WELLPOINT INC GRP | 23 | HUMANA GRP | 7 | 94 | 65 | 10 |
| Louisiana | 2015 | 5 | 4.1 | LOUISIANA HEALTH SERVS GRP | 53 | UNITEDHEALTH GRP | 22 | LOUISIANA HEALTH COOP INC | 14 | 89 | 53 | 61 |
| Maine | 2015 | 3 | 3 | MAINE COMM HEALTH OPTIONS | 81 | WELLPOINT INC GRP | 18 | HARVARD PILGRIM HTH CARE GRP | 1 | 100 | 81 | -46 |
| Maryland | 2015 | 5 | 5 | CAREFIRST INC GRP | 77 | KAISER FOUNDATION GRP | 17 | UNITEDHEALTH GRP | 3 | 97 | 77 | -18 |
| Massachusetts | 2015 | 10 | 9.9 | TUFTS HEALTH PLAN | 41 | NEIGHBORHOOD HEALTH PLAN INC | 25 | BOSTON MEDICAL CENTER HEALTH PLAN INC | 17 | 82 | 42 | 28 |
| Michigan | 2015 | 13 | 7.6 | BCBS OF MICHIGAN GRP | 67 | SPECTRUM HEALTH GRP | 14 | HUMANA MEDICAL PLAN OF MICHIGAN INC | 6 | 88 | 68 | -23 |
| Mississippi | 2015 | 3 | 2.9 | HUMANA GRP | 38 | UNITEDHEALTH GRP | 33 | CENTENE CORP GRP | 29 | 100 | 57 | 44 |
| Missouri | 2015 | 6 | 3.3 | AETNA GRP | 58 | WELLPOINT INC GRP | 15 | UNITEDHEALTH GRP | 13 | 86 | 66 | -12 |
| Montana | 2015 | 4 | 4 | HCSC GRP | 46 | MONTANA HEALTH COOP | 37 | PACIFICSOURCE HEALTH PLAN GRP | 15 | 98 | 47 | -8 |
| Nebraska | 2015 | 4 | 3.9 | AETNA GRP | 60 | BCBS OF NEBRASKA | 32 | COOPORTUNITY HEALTH | 5 | 97 | 60 | -20 |
| Nevada | 2015 | 5 | 4.1 | UNITEDHEALTH GRP | 42 | NEVADA HEALTH COOP | 27 | WELLPOINT INC GRP | 17 | 87 | 48 | 6 |
| New Hampshire | 2015 | 5 | 5 | WELLPOINT INC GRP | 60 | MINUTEMAN HEALTH INC | 17 | HARVARD PILGRIM HTH CARE GRP | 15 | 93 | 60 | -19 |
| New Jersey | 2015 | 5 | 5 | BCBS OF NJ GRP | 54 | INDEPENDENCE HEALTH GRP INC | 21 | FREELANCERS COOP OF NEW JERSEY | 21 | 96 | 54 | 9 |
| New Mexico | 2015 | 5 | 5 | HCSC GRP | 40 | NEW MEXICO HEALTH CONNECTIONS | 35 | PRESBYTERIAN HEALTHCARE SERVS GRP | 14 | 89 | 43 | -3 |
| New York | 2015 | 16 | 10 | NEW YORK STATE CATHOLIC HEALTH PLAN INC | 20 | FREELANCERS HEALTH SERVS CORP | 18 | HEALTHFIRST PHSP INC | 10 | 47 | 25 | 90 |
| North Carolina | 2015 | 3 | 2.7 | BCBS OF NORTH CAROLINA | 67 | AETNA GRP | 21 | UNITEDHEALTH GRP | 12 | 100 | 70 | -11 |
| North Dakota | 2015 | 3 | 3 | NORIDIAN MUTUAL INS CO | 69 | MEDICA GRP | 21 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 10 | 100 | 72 | -15 |
| Ohio | 2015 | 15 | 10 | MEDICAL MUTUAL OF OHIO | 27 | CARESOURCE MANAGEMENT GRP | 23 | WELLPOINT INC GRP | 11 | 61 | 41 | -13 |
| Oklahoma | 2015 | 4 | 3.6 | HCSC GRP | 98 | COMMUNITYCARE GRP | 1 | GLOBALHEALTH HOLDINGS GRP | 1 | 100 | 98 | -26 |
| Oregon | 2015 | 10 | 8.2 | OREGON DENTAL GRP | 42 | PREMERA BLUE CROSS GRP | 23 | PROVIDENCE HEALTH PLAN | 16 | 80 | 42 | 2 |
| Pennsylvania | 2015 | 9 | 4.9 | HIGHMARK GRP | 46 | INDEPENDENCE HEALTH GRP INC | 27 | UPMC HEALTH OPTIONS INC | 8 | 81 | 73 | -4 |
| Rhode Island | 2015 | 3 | 3 | NEIGHBORHOOD HLTH PLAN OF RI INC | 50 | BCBS OF RHODE ISLAND | 47 | UNITEDHEALTH GRP | 3 | 100 | 50 | 54 |
| South Carolina | 2015 | 4 | 3.6 | CONSUMERS CHOICE HEALTH INS CO | 43 | BCBS OF SC GRP | 42 | AETNA GRP | 15 | 100 | 59 | 20 |
| South Dakota | 2015 | 3 | 3 | AVERA HEALTH PLANS INC | 53 | SOUTH DAKOTA STATE MEDICAL HOLDING CO INC | 36 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 11 | 100 | 61 | 3 |
| Tennessee | 2015 | 5 | 4.1 | BCBS OF TN INC | 78 | COMM HEALTH ALLIANCE MUTUAL INS CO | 17 | HUMANA GRP | 5 | 99 | 78 | -46 |
| Texas | 2015 | 14 | 7.7 | HCSC GRP | 65 | HUMANA GRP | 10 | UNITEDHEALTH GRP | 9 | 85 | 69 | -44 |
| Utah | 2015 | 6 | 5.3 | IHC INC GRP | 49 | ARCHES MUTUAL INS CO | 24 | HUMANA GRP | 10 | 83 | 54 | 51 |
| Vermont | 2015 | 2 | 2 | BCBS OF VT GRP | 92 | MVP GRP | 8 | -- | -- | 100 | 92 | -44 |
| Virginia | 2015 | 7 | 4.4 | WELLPOINT INC GRP | 40 | AETNA GRP | 17 | KAISER FOUNDATION GRP | 15 | 72 | 51 | 9 |
| Washington | 2015 | 9 | 7.3 | PREMERA BLUE CROSS GRP | 49 | COORDINATED CARE CORP | 20 | GRP HEALTH COOP GRP | 14 | 83 | 49 | -33 |
| West Virginia | 2015 | 1 | 1 | HIGHMARK GRP | 100 | -- | -- | -- | -- | 100 | 100 | -33 |
| Wisconsin | 2015 | 15 | 6.3 | COMMON GROUND HEALTHCARE COOP | 17 | SECURITY HEALTH PLAN OF WISCONSIN INC | 16 | MOLINA HEALTHCARE INC GRP | 14 | 47 | 52 | 6 |
| Wyoming | 2015 | 2 | 2 | BCBS OF WYOMING | 58 | WINHEALTH PARTNERS | 42 | -- | -- | 100 | 61 | 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.