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.
Small-Group 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 | 2015 | 6 | BCBS OF ALABAMA GRP | 97 | UNITEDHEALTH GRP | 2 | VIVA HEALTH INC | 1 | 100 | 0 |
| Alaska | 2015 | 5 | PREMERA BLUE CROSS GRP | 71 | ASSURANT INC GRP | 10 | OREGON DENTAL GRP | 8 | 89 | 14 |
| Arizona | 2015 | 12 | BCBS OF ARIZONA INC | 25 | UNITEDHEALTH GRP | 22 | CENTENE CORP GRP | 21 | 67 | 42 |
| Arkansas | 2015 | 8 | ARKANSAS BCBS GRP | 67 | UNITEDHEALTH GRP | 20 | CATHOLIC HLTH INITIATIVES GRP | 12 | 99 | 5 |
| California | 2015 | 18 | KAISER FOUNDATION GRP | 34 | WELLPOINT INC GRP | 21 | BLUE SHIELD OF CALIFORNIA GRP | 18 | 74 | 30 |
| Colorado | 2015 | 10 | WELLPOINT INC GRP | 28 | KAISER FOUNDATION GRP | 25 | UNITEDHEALTH GRP | 24 | 77 | 20 |
| Connecticut | 2015 | 9 | HIP INS GRP | 38 | WELLPOINT INC GRP | 22 | AETNA GRP | 21 | 80 | -4 |
| Delaware | 2015 | 4 | HIGHMARK GRP | 70 | AETNA GRP | 29 | UNITEDHEALTH GRP | 1 | 100 | 5 |
| District of Columbia | 2015 | 7 | CAREFIRST INC GRP | 83 | UNITEDHEALTH GRP | 9 | KAISER FOUNDATION GRP | 4 | 97 | 4 |
| Florida | 2015 | 12 | BCBS OF FLORIDA INC | 35 | UNITEDHEALTH GRP | 33 | AETNA GRP | 13 | 82 | 23 |
| Georgia | 2015 | 14 | WELLPOINT INC GRP | 29 | HUMANA GRP | 27 | AETNA GRP | 22 | 78 | 7 |
| Hawaii | 2015 | 5 | HAWAII MEDICAL SERVS ASSOC | 47 | KAISER FOUNDATION GRP | 21 | UNIVERSITY HEALTH ALLIANCE | 18 | 86 | 10 |
| Idaho | 2015 | 11 | BLUE CROSS OF IDAHO HEALTH SERVS INC | 54 | REGENCE GRP | 29 | IHC INC GRP | 13 | 96 | -12 |
| Illinois | 2015 | 14 | HCSC GRP | 65 | UNITEDHEALTH GRP | 16 | HUMANA GRP | 7 | 88 | 22 |
| Indiana | 2015 | 18 | WELLPOINT INC GRP | 52 | UNITEDHEALTH GRP | 24 | PHP INDIANA GRP | 8 | 83 | 21 |
| Iowa | 2015 | 14 | WELLMARK GRP | 78 | UNITEDHEALTH GRP | 15 | AETNA GRP | 3 | 95 | 10 |
| Kansas | 2015 | 8 | BCBS OF KANSAS GRP | 64 | HUMANA GRP | 12 | UNITEDHEALTH GRP | 9 | 84 | 14 |
| Kentucky | 2015 | 8 | WELLPOINT INC GRP | 51 | HUMANA GRP | 39 | UNITEDHEALTH GRP | 6 | 96 | 7 |
| Louisiana | 2015 | 8 | LOUISIANA HEALTH SERVS GRP | 76 | HUMANA GRP | 14 | UNITEDHEALTH GRP | 7 | 97 | 5 |
| Maine | 2015 | 6 | HARVARD PILGRIM HTH CARE GRP | 44 | WELLPOINT INC GRP | 27 | AETNA GRP | 22 | 93 | -7 |
| Maryland | 2015 | 6 | CAREFIRST INC GRP | 67 | UNITEDHEALTH GRP | 13 | AETNA GRP | 10 | 91 | 8 |
| Massachusetts | 2015 | 11 | BCBS OF MA GRP | 42 | HARVARD PILGRIM HTH CARE GRP | 25 | TUFTS HEALTH PLAN | 12 | 79 | -6 |
| Michigan | 2015 | 21 | BCBS OF MICHIGAN GRP | 52 | SPECTRUM HEALTH GRP | 19 | UNITEDHEALTH GRP | 8 | 79 | 16 |
| Minnesota | 2015 | 8 | HEALTHPARTNERS GRP | 43 | BCBS OF MN GRP | 43 | PREFERREDONE GRP | 7 | 92 | 0 |
| Mississippi | 2015 | 7 | MISSISSIPPI INS GRP | 79 | UNITEDHEALTH GRP | 17 | HUMANA GRP | 3 | 99 | 3 |
| Missouri | 2015 | 11 | WELLPOINT INC GRP | 42 | UNITEDHEALTH GRP | 22 | AETNA GRP | 13 | 76 | 22 |
| Montana | 2015 | 8 | HCSC GRP | 71 | PACIFICSOURCE HEALTH PLAN GRP | 21 | MONTANA HEALTH COOP | 3 | 95 | 9 |
| Nebraska | 2015 | 8 | BCBS OF NEBRASKA | 38 | UNITEDHEALTH GRP | 33 | AETNA GRP | 18 | 89 | 12 |
| Nevada | 2015 | 11 | UNITEDHEALTH GRP | 50 | WELLPOINT INC GRP | 14 | AETNA GRP | 12 | 76 | 31 |
| New Hampshire | 2015 | 6 | WELLPOINT INC GRP | 56 | HARVARD PILGRIM HTH CARE GRP | 39 | MAINE COMM HEALTH OPTIONS | 4 | 99 | 1 |
| New Jersey | 2015 | 7 | BCBS OF NJ GRP | 54 | AETNA GRP | 18 | UNITEDHEALTH GRP | 16 | 88 | 8 |
| New Mexico | 2015 | 4 | HCSC GRP | 38 | PRESBYTERIAN HEALTHCARE SERVS GRP | 33 | NEW MEXICO HEALTH CONNECTIONS | 17 | 87 | -6 |
| New York | 2015 | 15 | UNITEDHEALTH GRP | 42 | LIFETIME HEALTHCARE GRP | 17 | AETNA GRP | 12 | 71 | 12 |
| North Carolina | 2015 | 10 | BCBS OF NORTH CAROLINA | 60 | UNITEDHEALTH GRP | 23 | AETNA GRP | 14 | 96 | 5 |
| North Dakota | 2015 | 5 | NORIDIAN MUTUAL INS CO | 83 | MEDICA GRP | 9 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 8 | 99 | 0 |
| Ohio | 2015 | 21 | WELLPOINT INC GRP | 37 | MEDICAL MUTUAL OF OHIO | 30 | UNITEDHEALTH GRP | 13 | 80 | 13 |
| Oklahoma | 2015 | 9 | HCSC GRP | 71 | UNITEDHEALTH GRP | 11 | COMMUNITYCARE GRP | 10 | 93 | 31 |
| Oregon | 2015 | 14 | PROVIDENCE HEALTH PLAN | 16 | KAISER FOUNDATION GRP | 16 | REGENCE GRP | 14 | 45 | 37 |
| Pennsylvania | 2015 | 14 | INDEPENDENCE HEALTH GRP INC | 26 | HIGHMARK GRP | 22 | UPMC HEALTH OPTIONS INC | 17 | 65 | 44 |
| Rhode Island | 2015 | 4 | BCBS OF RHODE ISLAND | 79 | UNITEDHEALTH GRP | 19 | TUFTS HEALTH PLAN | 2 | 100 | 1 |
| South Carolina | 2015 | 8 | BCBS OF SC GRP | 80 | UNITEDHEALTH GRP | 12 | AETNA GRP | 6 | 97 | 11 |
| South Dakota | 2015 | 8 | WELLMARK GRP | 61 | SOUTH DAKOTA STATE MEDICAL HOLDING CO INC | 24 | AVERA HEALTH PLANS INC | 8 | 93 | 6 |
| Tennessee | 2015 | 11 | BCBS OF TN INC | 65 | UNITEDHEALTH GRP | 20 | HUMANA GRP | 12 | 97 | 3 |
| Texas | 2015 | 18 | HCSC GRP | 60 | UNITEDHEALTH GRP | 18 | HUMANA GRP | 12 | 90 | 22 |
| Utah | 2015 | 10 | IHC INC GRP | 55 | REGENCE GRP | 17 | UNITEDHEALTH GRP | 12 | 84 | 28 |
| Vermont | 2015 | 3 | BCBS OF VT GRP | 89 | MVP GRP | 11 | CIGNA HEALTH GRP | 0 | 100 | 0 |
| Virginia | 2015 | 12 | WELLPOINT INC GRP | 45 | CAREFIRST INC GRP | 15 | AETNA GRP | 13 | 73 | 12 |
| Washington | 2015 | 9 | PREMERA BLUE CROSS GRP | 56 | REGENCE GRP | 18 | UNITEDHEALTH GRP | 8 | 82 | 19 |
| West Virginia | 2015 | 6 | HIGHMARK GRP | 81 | AETNA GRP | 15 | HEALTH PLAN GRP | 3 | 98 | 9 |
| Wisconsin | 2015 | 23 | UNITEDHEALTH GRP | 34 | WELLPOINT INC GRP | 12 | HUMANA GRP | 11 | 56 | 34 |
| Wyoming | 2015 | 6 | BCBS OF WYOMING | 70 | ASSURANT INC GRP | 16 | UNITEDHEALTH GRP | 7 | 92 | 14 |
- 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.