Corewell Health in Michigan: 257,090 Medicare Advantage members, 26.6% share, 1st of 16.
Corewell Health added 31,163 members (+13.8%) from Nov 2025 to Oct 2026 and stepped +10.5% at the 2026 election period against the market's +3.0%. It sells in 68 of Michigan’s 83 counties with visible members and leads 35, Humana just behind at 22.4%.
Corewell Health's twelve months in Michigan
Visible members each month, Nov 2025 to Oct 2026. The December-to-January step is the election period. The market line for the state is on the Michigan page.
Where Corewell Health's Michigan members are
The carrier’s five largest counties by visible members, with its share of each county’s visible Medicare Advantage members. It sells in 68 counties and leads 35 of them.
| County | Corewell Health members | Share of county | County visible members | County leader |
|---|---|---|---|---|
| Kent | 51,104 | 69.0% | 74,020 | Corewell Health |
| Ottawa | 29,085 | 75.0% | 38,789 | Corewell Health |
| Kalamazoo | 12,165 | 49.7% | 24,470 | Corewell Health |
| Muskegon | 11,293 | 43.2% | 26,161 | Corewell Health |
| Allegan | 11,003 | 68.2% | 16,144 | Corewell Health |
Corewell Health against the Michigan market
The carrier’s figures beside the state’s, each weighted by members. A difference is a difference, not a grade: a higher maximum or a lower rating is a design and a result, read in context.
top three hold 64.9%
market 4.02, +0.24, 2nd of 7 rated
market 81%, +2 points
market $6,950, +$0
| # | Carrier | Members | Share | Twelve months | Election step | Counties led | Rating | $0 premium |
|---|---|---|---|---|---|---|---|---|
| 1 | Corewell Health | 257,090 | 26.6% | +13.8% | +10.5% | 35 of 68 | 4.26 | 83% |
| 2 | Humana | 216,396 | 22.4% | +23.4% | +14.4% | 42 of 83 | 4.10 | 94% |
| 3 | Blue Cross Blue Shield of Michigan Mutual Ins. Co. | 154,667 | 16.0% | −30.1% | −28.4% | 4 of 83 | 4.50 | 28% |
| 4 | Henry Ford Health System | 107,561 | 11.1% | +75.8% | +56.0% | 2 of 58 | 3.80 | 92% |
| 5 | Aetna (CVS) | 88,600 | 9.2% | +11.4% | +4.9% | 0 of 69 | 3.83 | 98% |
| 6 | UnitedHealth | 63,523 | 6.6% | −13.5% | −14.1% | 0 of 63 | 3.09 | 100% |
| 7 | Centene | 29,670 | 3.1% | +11.7% | +20.9% | 0 of 47 | 3.00 | 100% |
What 2027 does to Corewell Health's plans in Michigan
The fate assigned to each of the carrier’s plans for 2027, joined to the members in it today.
26,951 members are in 2 plans that end and must choose again. 186,249 members are in 4 plans that drop at least one county; which counties is not stated. In all, 83% of Corewell Health’s Michigan members are in a plan whose service area or status changes.
The read on Corewell Health in Michigan is in Carrier Command.
Risk and rebate against the market, the five-test read on coding versus selection, Stars levers and next year's cut points, the election-period forecast and the county-by-county standing, written as a monthly page.
Corewell Health elsewhere, and the rest of Michigan
How these numbers are made
- Members are visible members: CMS suppresses any plan-county cell of ten or fewer, so small counties undercount. Market share excludes employer group plans.
- Enrollment is Oct 2026; the twelve months run Nov 2025 to Oct 2026; the election step compares December 2025 with January 2026.
- Corewell Health is the parent organization Corewell Health; its 12 plans in Michigan may sell under other brand names. The rating is the 2027 overall Star Rating of its contracts weighted by members in Michigan; $0 premium and the in-network maximum are the 2027 filings weighted by members today.
- Plan fates are the ones assigned for contract year 2027.
- Every figure comes from public CMS data as Livmor reads it, and the page is rebuilt when a new month posts. Livmor Carrier Command, public CMS data.