MA Enrollment Explorer / Parent organizations / Mass General Brigham Incorporated
Mass General Brigham Incorporated: Medicare Advantage enrollment and market share
Mass General Brigham Incorporated had 21,499 Medicare Advantage members in October 2026, #82 nationally with 0.06% of all MA enrollment. It gained 13,583 members (+171.6%) since October 2025, and has enrollment in 2 states and 11 counties with 11 or more members, leading the market in 2 of them. In the 2026 Annual Election Period (December to February) it gained 10,898 members (+131.9%). For 2027, 18,219 of its members are in plans that terminate and 0 in plans leaving their county, and it leaves 1 county entirely.
21KMA members, October 2026
+171.6%change since October 2025 (+13,583)
0.06%national MA share, rank 82
4contracts with enrollment
Largest states
| State | Members | Share of state MA |
|---|---|---|
| Massachusetts | 21,349 | 3.9% |
| New Hampshire | 14 | 0.0% |
Largest counties
| County | Members | Change since October 2025 | Share of county MA |
|---|---|---|---|
| Middlesex County, MA | 5,185 | +3,137 | 4.9% |
| Essex County, MA | 5,160 | +3,557 | 8.0% |
| Norfolk County, MA | 3,185 | +1,828 | 6.5% |
| Suffolk County, MA | 3,134 | +2,172 | 6.5% |
| Plymouth County, MA | 2,796 | +1,889 | 6.6% |
| Bristol County, MA | 1,070 | +660 | 2.0% |
| Worcester County, MA | 465 | +182 | 0.6% |
| Dukes County, MA | 240 | +50 | 51.0% |
| Nantucket County, MA | 85 | +8 | 63.9% |
| Barnstable County, MA | 29 | +17 | 0.1% |
| Rockingham County, NH | 14 | new | 0.1% |
Contracts
| Contract | Plan type | Oct 2024 | Oct 2025 | Oct 2026 |
|---|---|---|---|---|
| H9485 Mass General Brigham Health Plan | Local PPO | 2,120 | 6,806 | 18,342 |
| H6847 Mass General Brigham Health Plan | HMO/HMOPOS | 701 | 1,110 | 2,110 |
| H1611 Mass General Brigham Health Plan | HMO/HMOPOS | n/a | n/a | 543 |
| H0777 Mass General Brigham Health Plan | HMO/HMOPOS | n/a | n/a | 504 |
Star ratings for these contracts are in the MA Quality Dashboard.