Medicare Advantage (MA), termed Medicare Part C, has risen to be the leading selection for over half of all Medicare recipients. These plans are provided by private insurers sanctioned by the federal government and amalgamate Part A (hospital), Part B (medical), and frequently Part D (prescription medications) coverage, as well as additional perks such as vision, dental, hearing, and wellness benefits of largest medicare advantage plans.
- Market Share and Enrollment Trends
1.1 Concentration Among Top Insurers
Despite nearly 300 insurers presenting MA, enrollment remains significantly concentrated. As of March
2025, approximately 78.8% of MA participants were covered by merely 10 insurers. The top three are:
- UnitedHealthcare: ~9.9 million participants (~28.7% market share).
- Humana: ~5.7 million participants (~16.6% share).
- CVS Health (Aetna): ~4.1 million participants (~12.7% share).
In total, the top three control ~57.2% of the MA market. The top ten insurers constitute close to 80% of
enrollment.
The Centers for Medicare & Medicaid Services (CMS) anticipates ongoing growth in MA involvement—
from 54% in 2024 to 64% by 2034—heightening rivalry among primary insurers.
- The Largest Medicare Advantage Plans by Insurer
2.1 UnitedHealthcare
- Claims the largest market share (~28.7%) with ~9.9 million participants.
- Provides MA plans in 2,808 counties—only second to Humana.
- Recognized for the most extensive MA provider and dental networks, boasting over 1 million providers.
- CMS Star Rating: strong overall (3.95/5) with above-average satisfaction (3.41/5).
- Accessible in 49 states + D.C.—most extensive geographical reach.
Their vast scale, in conjunction with strong networks and collaborations (e.g. AARP), positions
UnitedHealthcare as the leading Medicare Advantage plan provider in the nation.
2.2 Humana
- Enrolls ~5.7 million beneficiaries (16.6% market share).
- Available in 2,848 counties—the broadest MA presence.
- Distinguished for Part B “give-back” plans that lessen your Part B premium.
- CMS Star Rating: 3.63 overall; many plans rated 4-star or better.
- Has partnerships (e.g., with USAA for veterans).
Humana’s extensive reach, give-back incentives, and veteran-oriented plans contribute to its role among the
largest Medicare Advantage plans.
2.3 CVS Health (Aetna)
- Enrolls ~4.1 million beneficiaries (~12.7% market share).
- Aetna MA is renowned for high CMS star ratings (4.29/5) and excellent member experience (~4.01/5).
- Available in 44 states + D.C.
- CVS Health also provides competitively priced choices through Cigna’s network and low-cost options.
Their blend of quality ratings, cost-effectiveness, and wide availability establishes them as one of the
foremost Medicare Advantage plans.
2.4 Elevance Health (formerly Anthem/Carelon)
- Maintains ~2 million participants (~6% share).
- Elevance delivers integrated care via Carelon Health: 125,000 patients in 9 states; hospitalizations 42%
below FFS. - Anthem has historically maintained a strong presence in various states, underpinned by network growth.
Their integrated care approach and national scope rank Elevance among the significant—and “largest”—
Medicare Advantage plans.
2.5 Centene
- A third-tier but growing participant with MA operations as part of broader Medicaid and Marketplace
activities. - Known for the WellCare acquisition and focusing on underserved demographics.
- While not in the top 3 nationally, their government contract scale positions them among the largest
Medicare Advantage plans in critical states.
2.6 Blue Cross Blue Shield Affiliates
- BCBS plans dominate market positions in six states and represented 30% of MA enrollment growth for
2025. - Especially strong through nonprofit regionals like Medical Mutual of Ohio.
- BCBS entities emerge as some of the largest Medicare Advantage plans based on state-specific presence.
- Geographic Reach vs. Enrollment
County coverage and total participants are both significant:
- Humana: largest county outreach (2,848 counties).
- UnitedHealthcare: slightly smaller coverage area (2,808 counties).
- CVS/Aetna and others possess less coverage but maintain robust enrollment where present.
Beneficiaries generally view 34 MA-PD plans and 42 overall MA plans in 2025; however, plan availability is
slightly declining in some regions. Overall, almost two-thirds of MA plans feature $0 premiums beyond Part
B.
- Why They’re the Largest Medicare Advantage Plans
4.1 Extensive Networks and Accessibility
- UnitedHealthcare: most extensive provider and dental network.
- Humana’s LPPO and give-back options diminish financial barriers.
- Aetna and CVS deliver impressive Medicare star ratings and access to retail health services such as
MinuteClinics.
4.2 Advantages and Competitive Edge - Low/no premium plans position MA as a formidable competitor against traditional Medicare.
- Additional features like dental, vision, OTC allowances, transportation still available in 2025 (although
some perks like OTC packages have seen a decline). - Give-back plans diminish Part B premiums—an advantage mainly offered by Humana.
4.3 Scale and Financial Benefits
- CMS raised MA compensation for 2026 beyond projections—expected extra $25 billion to insurers—
elevating United and Humana stocks. - Private insurers reap financial rewards from MA, which covers 15% of UnitedHealthcare’s beneficiaries yet
generates 46% of its income.
5.1 Quality Ratings
- Humana saw a downgrade for its largest plan from 4.5 to 3.5 stars, affecting member distribution.
- Aetna leads in star ratings; UHC and others have room to improve.
5.2 Legal and Fraud Concerns
- DOJ recently sued Aetna, Humana, and CVS Health for alleged broker kickbacks and steering tactics.
- Earlier whistleblower reports have accused insurers of gaming diagnostic coding to inflate reimbursements.
5.3 Policy and Privatization Debates
- Shifting toward MA as a national default is being debated politically, with critics citing taxpayer costs and access restrictions.
- Supporters point to expanded benefits and efficiency; opponents highlight issues with out-of-network access and fiscal sustainability.
6. The Future of the Largest Medicare Advantage Plans
- Growth: CMS projects MA will cover two-thirds of beneficiaries by 2034.
- Benefit Evolution: Insurers may continue cutting or reshaping benefits (e.g. expanded virtual care, nutrition support).
- Regulation: With growing scrutiny, reforms may focus on fraud prevention, payment adjustments, consumer safeguards.
- Market Dynamics: Mergers (e.g., Cigna’s divestiture, Centene acquisitions) could reshape who qualifies as the “largest.”
- Nonprofit Momentum: BCBS and other nonprofit insurers now drive nearly 45% of enrollment growth.
Conclusion
In 2025, when we reference the largest Medicare Advantage plans, we’re talking about those insurers with:
- The highest enrollment (UnitedHealthcare, Humana, CVS/Aetna).
- The widest geographic footprint (Humana, UHC).
- Strong CMS star ratings and broad networks (Aetna, UHC).
- Financial incentives and market influence (all major players backed by increased CMS payments).
These organizations dominate the landscape not only because they enroll the most people but also because they shape benefits, pricing, and national policy.
largest medicare advantages plans – that phrase signifies more than market share—it reflects the insurers setting standards for access, quality, coverage, and innovation in MA. Their reach impacts millions of seniors and those with disabilities, influencing how Medicare evolves.
If you’re choosing an MA plan, consider:
- Coverage area and provider network.
- Star ratings and quality metrics.
- Benefit design and costs (premiums, out-of-pocket maximums, extras).
- Financial stability and regulatory history.
Staying informed helps seniors navigate their options with clarity and confidence.
