Largest health insurance companies in the US: ranked by members, with premiums and Medicare enrollment

This list is for people who sell to health plans: claims and payment integrity vendors, care management and member engagement firms, provider network and data companies, IT and core administration platforms, call center and staffing providers, and brokers' partners. It ranks the 15 largest health insurers by members, gives each one's 2025 premiums or revenue, shows who leads Medicare Advantage from federal enrollment data, and explains where buying decisions sit inside a plan.

The 15 largest health insurance companies by members

Members at the end of 2025 as each company reports them in its 10-K, annual report or company profile, checked on 30 October 2026. Revenue is premiums earned for listed insurers (the cleanest measure of insurance size) and total revenue for nonprofit and mutual plans, which don't break out premiums the same way.

Premiums are premiums earned in the 2025 income statement. Nonprofit and mutual plans' figures are from their own 2025 annual reports, results releases or company profiles: they include care delivery (Kaiser's hospitals and medical groups, Highmark's Allegheny Health Network) and other businesses. Employee counts for UnitedHealth, CVS and Cigna cover the whole group, including Optum, pharmacies and Evernorth.

Member counts aren't directly comparable. A self-funded employer member pays the insurer an administration fee, not a premium, and Centene's and Humana's totals include stand-alone drug plan members that UnitedHealthcare and Aetna leave out of their medical counts. So read the table as "who touches the most people", and the premium column as "who carries the most insurance risk". By premiums, the order is UnitedHealth ($352.2 billion), Centene ($171.6 billion), Elevance ($164.6 billion), CVS's Aetna ($134.8 billion) and Humana ($122.8 billion).

Who leads each market

Health insurance is really five markets with different buyers, rules and leaders. Counts are from the companies' 10-K filings at the end of 2025, and from CMS's enrollment files for Medicare.

Each market has its own budget owner inside the insurer, which matters more to a seller than the overall rank: a Medicaid plan answers to state contract terms, while an employer business is judged on renewal rates and administrative cost.

Medicare Advantage: the largest parent organizations

CMS publishes enrollment for every Medicare contract each month, with the parent organization named. Summing the October 2026 file across Medicare Advantage contracts (local and regional coordinated care plans, private fee-for-service and medical savings account plans) gives 36.0 million enrollees under 166 parent organizations.

Our sum of CMS's Monthly Enrollment by Contract file for October 2026; contracts with 10 or fewer enrollees are suppressed by CMS and counted as zero. Cost plans, PACE and stand-alone drug plans are excluded. Shares are of the 36,024,867 total.

The top five parents hold 68.6% of enrollment. Below them the market is long: 16 parents have between 200,000 and 1 million enrollees, 36 have between 50,000 and 200,000, and 109 have fewer than 50,000. Cigna is absent because it sold its Medicare Advantage, stand-alone drug plan and supplemental businesses to HCSC on 19 March 2025, according to Cigna's 10-K.

How this list is built

• What's counted. Members at year-end 2025 as each company defines them, and premiums earned (listed insurers) or total revenue (nonprofits) for 2025. We opened each 10-K's membership table, and each nonprofit's annual report, release or profile.
• Who's left out. Blue plans that don't publish a 2025 member count in their own reports, such as GuideWell (Florida Blue) and Independence Health Group; both appear in the Medicare data below. There are 33 independent Blue Cross Blue Shield licensees, according to Elevance's 10-K. Insurers that sell mainly dental, vision or supplemental cover are also left out.
• Other lists. ValuePenguin ranks insurers by group and individual premiums from statutory filings, and the NAIC and AM Best publish market share data. They use different scopes; we didn't copy their rankings. For property, casualty and life insurers, see the largest insurance companies.

How many health insurers there are

County Business Patterns counted 6,147 establishments of direct health and medical insurance carriers (NAICS 524114) in 2023, with 636,006 employees and $61.3 billion in annual payroll. These are offices, not companies: 3,028 have fewer than five employees (often local sales and service offices), while 150 have 1,000 or more. Florida has the most establishments (746), followed by California (530), Texas (356) and Pennsylvania (347). For a local count, see the market reports such as insurance companies in Florida.

Where buying decisions sit inside a health plan

General guidance, with figures from the companies' filings:

• Claims and payment integrity. HCSC alone handles an average of 1.7 million claims a day and managed $150.4 billion of medical spend in 2025. Claims operations, special investigations and payment integrity teams buy coding, editing, recovery and fraud tools, and are measured on savings.
• Clinical and care management. UnitedHealth reported nearly 165,000 clinical professionals. Medical directors and care management leaders buy programs that lower costs for high-need members, and in Medicare Advantage, anything that improves quality (Star) ratings.
• Distribution. Humana reported about 1,000 sales representatives and 2,200 telemarketing representatives for Medicare products. Sales and broker channel leaders buy lead, enrollment and broker tools, inside strict Medicare marketing rules.
• Government programs. Medicaid contracts are won through state procurements, so plan leaders buy what helps them win and keep those contracts: community partnerships, reporting, member outreach.
• IT and administration. Core administration, member portals and data platforms are long, committee-led purchases, with security review and procurement involved from the start.

Worked example: a quality-ratings vendor targeting mid-size Medicare Advantage plans

Illustrative example. The company, prices and rates are invented; plan counts come from CMS's October 2026 enrollment file.

The seller: StarPath Outreach (starpath.example) runs member outreach that closes care gaps counted in Medicare Star ratings. The question: which plans to call first.

1. Pick the tier. The five largest parents have national vendors and long procurement cycles. The 16 parents with 200,000 to 1 million enrollees cover 6,822,913 people and are big enough to buy, small enough to move quickly.
2. Add the next tier. The 36 parents with 50,000 to 200,000 enrollees are a second list for a lighter offer.
3. Find the owners. At each plan, the vice president of Stars or quality, the Medicare president and the chief medical officer. Regional Blues and provider-owned plans often combine these roles.
4. Do the arithmetic. At an assumed $0.25 per member per month, a plan with 300,000 enrollees is worth $900,000 a year ($0.25 × 300,000 × 12). If StarPath reaches decision makers at 12 of the 16 plans and wins two, that's about $1.8 million a year.

Checking each plan's Star ratings, recent leadership changes and contract footprint is the slow part at this volume; Bebop researches each account in a list and writes a playbook with who to contact and the angle to open with.

Subject: [plan name] Star measures for [measurement year]

Hi [first name],

[Plan name] has about [enrollment] Medicare Advantage members in [states], and I saw [a change: new Stars leadership / a rating change / a service area expansion].

Plans your size often tell us their hardest measures are the ones that need a member to act, such as screenings and medication adherence.

We run outreach that closes those gaps and report results by measure each month. Would 20 minutes be useful to compare notes on the measures you're targeting this year?

[Your name]
[Phone number]

Common mistakes

• Comparing member counts without definitions. Self-funded, drug-plan and BlueCard members inflate some totals.
• Treating revenue as insurance size. Most of CVS's and Cigna's revenue is pharmacy and pharmacy benefits: Cigna's Evernorth segment reported $235.0 billion of revenue in 2025.
• Pitching the whole company. Medicare, Medicaid and employer businesses have separate leaders and budgets.
• Ignoring the rules. Medicare marketing and Medicaid contract terms limit what a plan can buy and say.

Next step: see how the insurers fit into the wider industry in the largest healthcare companies.