Payer Pulse
Medicare's largest payers look very different once you separate the drug plans from the health plans.
CMS enrollment through — / — Star Ratings / Daily close, adjusted
Report 01: Medicare / Report 02: Medicaid / new: Report 03, The duals seam
Four companies dominate Medicare. They are not selling the same product.
Medicare Advantage share of each company's own Medicare members
Rank these four by Medicare Advantage and you get one order. Rank them by standalone drug plans and you get exactly the reverse, all four positions flipped. Most coverage only runs the first ranking, which is why Centene's actual position, the largest standalone drug-plan sponsor in the country, mostly goes unseen. Its Medicare book is almost entirely drug plans, UnitedHealth's and Humana's are the opposite, and CVS sits near an even split.
That matters more this year than last. The federal support holding drug-plan premiums down was cut back in 2026 and expires after it, the market leader changed hands in 2024, and one of these four scaled in only last winter. Panel 02 has the history; the notes work through who is exposed.
Scope: Medicare only, which is most of Humana's business and a minority of the other three. These four only, so Kaiser, Elevance and the Blues plans are absent. Compare them as Medicare payers, not as companies. The Medicaid side is now its own report.
Medicare Advantage enrollment
Panel 01Medicare Advantage members by parent company, rolled up from every contract each one owns. Sub-brands count toward their parent: Wellcare and Ascension Complete to Centene, Peoples Health and KelseyCare to UnitedHealth Group, CarePlus and iCare to Humana, Aetna Medicare to CVS Health. Counts here come from CMS's county-level file, which masks counties with ten or fewer members, so they run a few tenths of a percent below the contract-level totals in the finding above. Both are real CMS figures; the gap is the masking.
Medicare Advantage only. Centene's roughly 12M Medicaid members are larger than its entire Medicare book, so this panel shows a small slice of that company and most of Humana. Read across the four with that in mind: the Medicaid report shows the other side.
Medicare product mix
Panel 02Medicare Advantage is only part of the picture. Standalone Part D drug plans (PDP) are a separate product with separate economics, and the mix between them differs sharply by company. Panel 01 counts MA only, which understates Centene in particular. The two charts below are kept apart deliberately: the ranking inverts between them.
Both charts count members, and a member is not a unit of revenue. Standalone Part D is thin, low-premium coverage; Medicare Advantage carries the full medical benefit at many times the premium per member. So a large drug-plan book is worth far less per head than the same number of MA members, and headcount overstates how much of a company's economics Part D represents. Read these as market position, not as size of business.
The bars above are a single month. Over three years the order changes hands: the lead passes at the start of 2024, and one line steps up sharply at the end. The notes below work through what happened and why it matters.
Star Ratings
Panel 03Analyst notes
Read alongsideObservations about an industry, not investment advice.
Share price
ContextWhole-company prices, not the Medicare business. CVS is up over this window while the other three are down, and almost none of that is Aetna Medicare: it is pharmacy, PBM and retail. Nothing above drives anything below, which is why this sits outside the analysis rather than inside it.