Medicare Advantage in Rock County, Wisconsin
18,879 people in Rock County, Wisconsin were enrolled in Medicare Advantage in October 2026, 49.7% of 38,003 eligible beneficiaries (−1.1 pts since October 2025). UnitedHealth Group, Inc. is the largest parent organization with 44% of reported enrollment; 8 parent organizations have 11 or more members and the HHI is 2,861 (highly concentrated). HRSA classifies the county as partly rural. For 2027, 1,859 members here are in plans that terminate or leave the county. MA plans offered go from 28 to 24.
Parent organizations in Rock County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| UnitedHealth Group, Inc. | 8,362 | −243 | 44.5% |
| Humana Inc. | 3,773 | +646 | 20.1% |
| Medica Holding Company | 3,140 | −73 | 16.7% |
| CVS Health Corporation | 2,534 | +913 | 13.5% |
| Elevance Health, Inc. | 846 | −1,138 | 4.5% |
| Molina Healthcare, Inc. | 99 | +39 | 0.5% |
| Network Health, Inc. | 38 | +19 | 0.2% |
| Health Care Service Corporation | 11 | new | under 0.1% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 8,104 beneficiaries in Rock County were assigned to 59 Medicare Shared Savings Program ACOs, 59.0% of assignable Original Medicare beneficiaries. Together, roughly 79% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.