Medicare Advantage in Nantucket County, Massachusetts
151 people in Nantucket County, Massachusetts were enrolled in Medicare Advantage in October 2026, 6.2% of 2,424 eligible beneficiaries (+0.2 pts since October 2025). Mass General Brigham Incorporated is the largest parent organization with 64% of reported enrollment; 3 parent organizations have 11 or more members and the HHI is 4,746 (highly concentrated). HRSA classifies the county as partly rural. For 2027, 68 members here are in plans that terminate or leave the county. MA plans offered go from 4 to 3.
Parent organizations in Nantucket County
| Parent organization | Members | Change since October 2025 | Share |
|---|---|---|---|
| Mass General Brigham Incorporated | 85 | +8 | 63.9% |
| UnitedHealth Group, Inc. | 27 | +2 | 20.3% |
| CVS Health Corporation | 21 | −1 | 15.8% |
CMS suppresses county and contract counts of 10 or fewer; shares are of reported enrollment.
Value-based care alongside MA
In PY 2024, 1,253 beneficiaries in Nantucket County were assigned to 29 Medicare Shared Savings Program ACOs, 75.6% of assignable Original Medicare beneficiaries. Together, roughly 77% of all Medicare beneficiaries in the county are in Medicare Advantage or an MSSP ACO. See the ACOs in the MSSP Explorer.