Direct Answer
Managed care organizations (MCOs) collect premiums from employers, government programs, and individuals, and pay medical claims to providers. Profitability is measured by the medical loss ratio (MLR): medical costs as a percentage of premium. Lower MLR means higher underwriting margin. Medicare Advantage (MA) is the fastest-growing segment, with government-set rates and significant actuarial risk.
Managed Care Business Model: Premium, MLR, and Segments
MCOs operate across four primary segments: Commercial (employer-sponsored and individual), Medicaid managed care (state-contracted), Medicare Advantage (government-subsidized private plans), and Medicare Part D (prescription drug plans). Each has distinct rate-setting mechanisms, regulatory requirements, and margin profiles.
Commercial insurance earns risk-based premiums with margin driven by underwriting. Medicaid and Medicare Advantage earn government-contracted rates with risk adjustment based on member health status. The ACA's 80/85% minimum MLR requirements limit how much margin commercial insurers can earn on premiums.
Vertical integration has transformed the industry: CVS Health acquired Aetna, UnitedHealth Group owns Optum (pharmacy benefit management, analytics, care delivery), and Cigna owns Express Scripts. These combinations allow carriers to capture value across pharmacy, clinical services, and administration.
Medical Loss Ratio: The Primary Profitability Measure
The medical loss ratio (MLR) is medical costs divided by premium revenue. An MLR of 85% means 85 cents of every premium dollar pays for medical care; 15 cents covers administrative costs and profit. The ACA requires MLRs of at least 80% for individual/small group and 85% for large group; excess profit must be rebated to members.
MLR varies significantly by segment. Medicaid typically runs 88-92%; commercial runs 82-86%; Medicare Advantage historically ran 82-86% but has risen sharply in 2023-2024 as utilization returned post-COVID and risk scores normalized.
Unexpected MLR increases are the most common source of guidance cuts in managed care. Key drivers include utilization (how often members seek care), unit cost inflation (provider rate increases, drug prices), acuity mix (sicker members using more care), and coding accuracy in Medicare Advantage risk scores.
Medicare Advantage: Growth Engine and Risk Concentration
Medicare Advantage allows Medicare beneficiaries to enroll in private plans that receive capitated payments from CMS. Plans must provide at least standard Medicare benefits and may add supplemental benefits (dental, vision, hearing). MA enrollment has grown from about 25% of eligible Medicare beneficiaries in 2010 to about 54% in 2024.
MA economics depend critically on risk scores (HCC risk adjustment): CMS pays more for sicker members. Aggressive risk score coding inflated payments for some plans; CMS has implemented "V28" risk model updates that reduced risk scores for many members, directly cutting plan revenue and pressuring MLRs in 2024.
Star ratings (1-5) determine quality bonuses that can add 5% to payments. Plans with 4+ stars receive significantly higher payments; falling below 4 stars materially impacts economics. Most large national plans work hard to maintain 4-star status.
Major Players: UnitedHealth, CVS/Aetna, Cigna, Humana
UnitedHealth Group (UNH) is the largest US health insurer, with Optum (healthcare services, analytics, pharmacy) generating roughly half of operating earnings. Its scale creates data and cost advantages that smaller competitors struggle to replicate.
CVS Health (CVS) owns Aetna (insurance), CVS Pharmacy (retail), Caremark (PBM), and MinuteClinic/Oak Street Health (care delivery). The integration thesis is that owning the patient relationship across insurance, pharmacy, and care delivery reduces costs and improves outcomes.
Cigna (CI) owns Evernorth (pharmacy and care services, including Express Scripts PBM) and Cigna Healthcare. Cigna has been more focused on commercial and specialty pharmacy than Medicare Advantage.
Humana (HUM) is the most Medicare Advantage-concentrated of the large carriers (individual Medicare Advantage was 70.3% of its 2025 premiums and services revenue and all Medicare products 82.6%), making it especially sensitive to CMS rate changes and MA utilization trends. It experienced significant 2024 earnings pressure from elevated MA costs.
Investment Considerations: Government Rate Risk and Regulatory Exposure
Managed care stocks trade on MLR trajectory and EPS estimates. Guidance cuts driven by unexpected MLR increases produce sharp stock declines. The cadence of quarterly MLR reporting (and whether utilization is "normalizing" or "elevating") drives near-term sentiment.
Government rate risk is structural: CMS publishes a draft Advance Notice in late January or early February and the final Medicare Advantage Rate Announcement by the first Monday in April, setting payment rates for the following year. Adverse rate decisions can immediately impair MCO earnings if they cannot be offset by benefit reductions or premium increases.
The industry faces regulatory scrutiny around prior authorization practices, network adequacy, and MA marketing. The Inflation Reduction Act's Medicare drug price negotiation provisions affect Part D economics. State Medicaid redeterminations post-COVID have reduced Medicaid membership as ineligible members were disenrolled.
FAQ
What is the medical loss ratio (MLR)?
The medical loss ratio (MLR) is medical claims costs divided by premium revenue. An 85% MLR means 85 cents of every premium dollar pays for healthcare; 15 cents covers administration and profit. The ACA requires minimum MLRs of 80% (individual/small group) and 85% (large group), with excess profit rebated to members. For investors, rising MLRs are the primary red flag: unexpected MLR increases are the most common trigger for managed care earnings cuts.
How does Medicare Advantage work?
Medicare Advantage (MA) allows Medicare beneficiaries who have both Part A and Part B, including those under 65 who qualify through disability, to enroll in private health plans that receive capitated (per-member, per-month) payments from CMS. Plans must provide at least standard Medicare benefits and typically offer supplemental benefits like dental and vision. CMS adjusts payments for member health status (risk scores) and quality (Star ratings). MA now covers over half of all Medicare beneficiaries and is the fastest-growing managed care segment.
Why did managed care stocks fall sharply in 2024?
Multiple large MCOs reported elevated medical loss ratios in 2023-2024, particularly in Medicare Advantage. Factors included: post-COVID utilization normalization (pent-up demand returning), CMS V28 risk model updates that reduced risk scores and thus capitated payment rates, and higher-than-expected acuity among MA members. Several large managed care companies reported elevated medical costs and adjusted their earnings outlooks during 2024, and the resulting stock declines spread across the sector.
What is the role of pharmacy benefit managers (PBMs) in managed care?
PBMs negotiate drug prices with manufacturers, process pharmacy claims, and manage formularies on behalf of health plans and employers. UnitedHealth's OptumRx, CVS Caremark, and Cigna's Express Scripts control roughly 80% of the US PBM market. Vertical integration of PBMs into health insurers creates both cost-saving synergies and regulatory scrutiny around conflicts of interest, particularly in formulary design and drug pricing practices.