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 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 | 2011 | 27 | BCBS OF ALABAMA | 90 | UNITEDHEALTH GRP | 5 | HUMANA GRP | 2 | 97 | 3 |
| Alaska | 2011 | 13 | PREMERA BLUE CROSS GRP | 58 | AETNA INC | 9 | ASSURANT INC | 9 | 76 | 31 |
| Arizona | 2011 | 30 | BCBS OF ARIZONA INC | 49 | UNITEDHEALTH GRP | 22 | AETNA INC | 6 | 77 | -1 |
| Arkansas | 2011 | 32 | ARKANSAS BCBS GRP | 79 | UNITEDHEALTH GRP | 8 | QCA HEALTH PLAN INC | 5 | 91 | 9 |
| California | 2011 | 45 | WELLPOINT INC GRP | 37 | KAISER FOUNDATION GRP | 20 | BLUE SHIELD OF CALIFORNIA GRP | 20 | 78 | 1 |
| Colorado | 2011 | 35 | WELLPOINT INC GRP | 32 | ASSURANT INC | 11 | HUMANA GRP | 10 | 53 | 30 |
| Connecticut | 2011 | 26 | WELLPOINT INC GRP | 48 | UNITEDHEALTH GRP | 20 | AETNA INC | 16 | 84 | 18 |
| Delaware | 2011 | 20 | BCBSD INC | 51 | UNITEDHEALTH GRP | 19 | AETNA INC | 15 | 85 | 18 |
| District of Columbia | 2011 | 18 | CAREFIRST INC GRP | 69 | AETNA INC | 11 | KAISER FOUNDATION GRP | 8 | 88 | 14 |
| Florida | 2011 | 40 | BCBS OF FLORIDA INC | 47 | UNITEDHEALTH GRP | 16 | HUMANA GRP | 10 | 73 | 12 |
| Georgia | 2011 | 38 | WELLPOINT INC GRP | 48 | AETNA INC | 10 | COVENTRY HEALTH CARE INC | 10 | 68 | 4 |
| Hawaii | 2011 | 14 | HAWAII MEDICAL SERVS ASSOC | 52 | KAISER FOUNDATION GRP | 46 | UNITED STATES LIFE | 1 | 99 | 1 |
| Idaho | 2011 | 23 | BLUE CROSS OF IDAHO HEALTH SERVS INC | 44 | REGENCE GRP | 37 | PACIFICSOURCE HEALTH PLAN GRP | 11 | 93 | -4 |
| Illinois | 2011 | 42 | HCSC GRP | 66 | HUMANA GRP | 7 | UNITEDHEALTH GRP | 6 | 79 | 10 |
| Indiana | 2011 | 37 | WELLPOINT INC GRP | 62 | UNITEDHEALTH GRP | 13 | ASSURANT INC | 7 | 82 | 16 |
| Iowa | 2011 | 33 | WELLMARK GRP | 83 | UNITEDHEALTH GRP | 5 | ASSURANT INC | 4 | 92 | 7 |
| Kansas | 2011 | 35 | BCBS OF KANSAS INC | 47 | BCBS OF KC GRP | 19 | COVENTRY CORP GRP | 11 | 76 | 20 |
| Kentucky | 2011 | 27 | WELLPOINT INC GRP | 79 | HUMANA GRP | 15 | UNITEDHEALTH GRP | 2 | 96 | 3 |
| Louisiana | 2011 | 34 | LOUISIANA HEALTH SERVS GRP | 72 | HUMANA GRP | 7 | COVENTRY HEALTH CARE INC | 6 | 85 | 14 |
| Maine | 2011 | 20 | WELLPOINT INC GRP | 45 | HEALTHMARKETS GRP | 34 | HARVARD PILGRIM HTH CARE GRP | 13 | 92 | 8 |
| Maryland | 2011 | 27 | CAREFIRST INC GRP | 70 | UNITEDHEALTH GRP | 15 | AETNA INC | 4 | 88 | 13 |
| Massachusetts | 2011 | 31 | BCBS OF MA GRP | 63 | HARVARD PILGRIM HTH CARE GRP | 18 | FALLON GRP | 7 | 88 | -6 |
| Michigan | 2011 | 41 | BCBS OF MI GRP | 56 | UNITEDHEALTH GRP | 14 | ASSURANT INC | 6 | 77 | 14 |
| Minnesota | 2011 | 36 | BCBS OF MN GRP | 63 | MEDICA GRP | 13 | ASSURANT INC | 9 | 85 | -3 |
| Mississippi | 2011 | 30 | MISSISSIPPI INS GRP | 57 | UNITEDHEALTH GRP | 15 | HUMANA GRP | 12 | 83 | 9 |
| Missouri | 2011 | 37 | WELLPOINT INC GRP | 32 | UNITEDHEALTH GRP | 20 | BCBS OF KC GRP | 18 | 69 | 14 |
| Montana | 2011 | 25 | BCBS OF MONTANA | 56 | ASSURANT INC | 25 | AMERICAN REPUBLIC MUT GRP | 5 | 85 | 17 |
| Nebraska | 2011 | 31 | BCBS OF NEBRASKA | 65 | UNITEDHEALTH GRP | 14 | ASSURANT INC | 9 | 88 | 7 |
| Nevada | 2011 | 24 | UNITEDHEALTH GRP | 42 | WELLPOINT INC GRP | 33 | AETNA INC | 8 | 83 | -6 |
| New Hampshire | 2011 | 20 | WELLPOINT INC GRP | 76 | HEALTHMARKETS GRP | 9 | ASSURANT INC | 8 | 93 | 7 |
| New Jersey | 2011 | 24 | BCBS OF NJ GRP | 63 | UNITEDHEALTH GRP | 16 | AEGON US HOLDING GRP | 10 | 90 | 8 |
| New Mexico | 2011 | 28 | HCSC GRP | 52 | PRESBYTERIAN HEALTHCARE SERVS GRP | 34 | ARDENT HEALTH SERVS | 4 | 90 | -15 |
| New York | 2011 | 38 | WELLPOINT INC GRP | 25 | UNITEDHEALTH GRP | 17 | LIFETIME HEALTHCARE GRP | 13 | 56 | -1 |
| North Carolina | 2011 | 31 | BCBS OF NORTH CAROLINA | 83 | WELLPATH SELECT INC | 4 | UNITEDHEALTH GRP | 3 | 90 | -2 |
| North Dakota | 2011 | 21 | NORIDIAN MUTUAL INS CO | 75 | ASSURANT INC | 11 | AMERICAN REPUBLIC MUT GRP | 4 | 90 | 11 |
| Ohio | 2011 | 43 | WELLPOINT INC GRP | 36 | MEDICAL MUTUAL OF OHIO | 31 | UNITEDHEALTH GRP | 13 | 80 | -30 |
| Oklahoma | 2011 | 30 | HCSC GRP | 58 | UNITEDHEALTH GRP | 14 | ASSURANT INC | 7 | 79 | 8 |
| Oregon | 2011 | 31 | REGENCE GRP | 35 | OREGON DENTAL GRP | 16 | PREMERA BLUE CROSS GRP | 14 | 65 | 10 |
| Pennsylvania | 2011 | 38 | HIGHMARK INC | 33 | INDEPENDENCE BLUE CROSS GRP | 25 | AETNA INC | 14 | 72 | 8 |
| Rhode Island | 2011 | 14 | BCBS OF RHODE ISLAND | 95 | UNITEDHEALTH GRP | 4 | NEW YORK LIFE GRP | 0 | 100 | 0 |
| South Carolina | 2011 | 31 | BCBS OF SC GRP | 55 | UNITEDHEALTH GRP | 20 | ASSURANT INC | 5 | 80 | 18 |
| South Dakota | 2011 | 30 | WELLMARK GRP | 74 | DAKOTACARE | 8 | SANFORD HEALTH PLAN/SANFORD HEALTH PLAN OF MINNESOTA | 7 | 89 | 12 |
| Tennessee | 2011 | 33 | TRH HEALTH INS CO | 37 | BCBS OF TN INC | 36 | UNITEDHEALTH GRP | 7 | 80 | -15 |
| Texas | 2011 | 50 | HCSC GRP | 57 | UNITEDHEALTH GRP | 9 | HUMANA GRP | 8 | 74 | -19 |
| Utah | 2011 | 24 | SELECTHEALTH & AFFILIATED COMPANIES | 43 | HUMANA GRP | 26 | REGENCE GRP | 17 | 86 | 8 |
| Vermont | 2011 | 16 | BCBS OF VT GRP | 77 | AEGON US HOLDING GRP | 14 | MVP GRP | 8 | 99 | 1 |
| Virginia | 2011 | 32 | WELLPOINT INC GRP | 74 | CAREFIRST INC GRP | 7 | UNITEDHEALTH GRP | 5 | 86 | -9 |
| Washington | 2011 | 30 | REGENCE GRP | 37 | PREMERA BLUE CROSS GRP | 36 | GROUP HEALTH COOPERATIVE | 23 | 96 | -25 |
| West Virginia | 2011 | 27 | HIGHMARK INC | 44 | UNITEDHEALTH GRP | 23 | COVENTRY CORP GRP | 11 | 78 | 28 |
| Wisconsin | 2011 | 42 | WISCONSIN PHYSICIANS SERVICES INSURANCE CORPORATION | 23 | WELLPOINT INC GRP | 19 | UNITEDHEALTH GRP | 16 | 59 | -3 |
| Wyoming | 2011 | 25 | BCBS OF WYOMING | 38 | ASSURANT INC | 18 | UNITEDHEALTH GRP | 15 | 71 | 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.
- 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.