Managed Care: The Most Misunderstood Corner of Healthcare

Eighty-five cents. That's the floor — set by federal law — on how many cents of every large-group or Medicare Advantage premium dollar a managed care company must pay out in medical claims and quality-improvement spending before it's allowed to keep the rest. Fall short of that Medical Loss Ratio threshold and the insurer owes policyholders a rebate check. Sounds like a business with the ceiling nailed shut. It isn't.

UnitedHealth Group, Elevance Health, Cigna, Humana, and Centene collectively generated close to a trillion dollars of combined revenue in fiscal year 2023 — and most generalist coverage still treats them as five variations on the same business: collect premiums, pay claims, keep the spread. That description was roughly accurate in 1995. It misses almost everything that matters about how these five companies compete with each other today, because the industry structure underneath the shared label has split into genuinely different business models. The differences show up directly in margin composition, growth strategy, and regulatory exposure.

What follows works through that structure in three layers: the loss-ratio constraint that shapes every insurer's incentives, the competitive roles the five majors actually occupy, and the vertically integrated pharmacy business that's become the industry's most consequential — and most politically exposed — growth engine.

The Medical Loss Ratio: Managed Care's Central Constraint

Start with the constraint, because nothing else about the sector makes sense until you understand what it does and doesn't cap.

Medical Loss Ratio (MLR): the share of premium revenue an insurer spends on medical claims and quality-improvement activities, as opposed to administration, marketing, and profit. Under the Affordable Care Act, insurers must maintain an MLR of at least 85% for large-group and Medicare Advantage plans, and at least 80% for individual and small-group plans — falling short triggers a rebate to policyholders.

Read that rule carelessly and you'd conclude margins are capped at roughly 15% of premium. They aren't, and the gap between the rule's intent and its practical effect is where the real strategy lives. The 85% floor caps margin as a percentage of premium — it says nothing about the absolute dollar amount of profit, and nothing at all about non-premium revenue. Grow the premium base and the same margin percentage produces more profit dollars. Shift business mix toward products where risk-adjustment revenue runs richer, like Medicare Advantage. And build revenue lines the MLR rule doesn't touch at all — pharmacy benefit management, care delivery, data and analytics — and you've built a growth engine the rebate rule was never designed to constrain.

UnitedHealthcare's own numbers illustrate both the ceiling and how insurers grow around it. The segment's medical care ratio came in at 83.2% for full-year 2023, per the company's 10-K — up from 82.0% in 2022, and still comfortably under the regulatory floor with room to absorb a bad claims year before a rebate becomes a live risk. UnitedHealth Group's total 2023 revenue exceeded $371 billion, with a rapidly growing share coming from Optum — the segment that sits entirely outside the MLR rule's reach.

Five Insurers, Three Competitive Roles

Grouping the five majors by market capitalization or headline revenue obscures more than it reveals. Grouping them by what they actually compete on produces three roles, not five interchangeable insurers.

• Scale incumbents — UnitedHealth Group and Elevance Health. UnitedHealth is the largest by a wide margin, with 2023 revenue above $371 billion spanning UnitedHealthcare's insurance operations and Optum's health-services, pharmacy, and technology arm. Elevance Health, the Blue Cross Blue Shield licensee across 14 states, reported 2023 operating revenue of roughly $170 billion and has built its own Optum analogue — Carelon — to capture services revenue outside the MLR ceiling. Both compete on breadth: enough covered lives and enough adjacent service lines that no single product line's margin pressure moves the whole company.
• Diversified challengers — Cigna and Humana. Cigna's 2023 revenue reached approximately $195 billion, and the substantial majority of it — about $153.5 billion — came from Evernorth, its health-services and pharmacy-benefit arm built around Express Scripts, not from underwriting insurance risk directly. Humana runs close to the opposite concentration: roughly $105 billion of 2023 revenue, weighted overwhelmingly toward individual Medicare Advantage, where the company reported close to $79 billion of premium from that single product line. Cigna has diversified away from insurance risk. Humana has concentrated into a single, favorable-but-exposed government product.
• The Medicaid specialist — Centene. Centene reported 2023 total revenue of $154.0 billion and closed the year with 27.5 million members across its plans, the large majority in Medicaid managed care — a franchise built on serving low-income populations that scale-focused competitors historically found administratively unattractive to pursue. That specialization is a genuine moat in normal periods and a genuine liability during Medicaid redeterminations, the post-pandemic eligibility reviews that shrank the rolls Centene depends on most.

Notice what connects Elevance's Carelon, Cigna's Evernorth, and UnitedHealth's Optum: all three built a pharmacy benefit manager into their core structure, and none of that revenue counts against the 85% ceiling. That's not a coincidence. It's the industry's actual growth strategy.

PBM Vertical Integration: Why Insurers Bought the Pharmacy Supply Chain

A pharmacy benefit manager negotiates drug prices between manufacturers, pharmacies, and health plans — collecting rebates from manufacturers in exchange for favorable formulary placement, and earning spread revenue on the difference between what it charges a plan sponsor and what it reimburses a pharmacy. Own the PBM and an insurer captures margin on both sides of a claim: underwriting margin on the medical side, spread and rebate margin on the pharmacy side, plus the data advantage of seeing a member's full medical and pharmacy history in one system.

UnitedHealth's Optum Rx, Cigna's Evernorth (built on the 2018 Express Scripts acquisition), and Elevance's CarelonRx are the three biggest examples of this structure. The resulting 'big three' PBMs process something close to 80% of US prescription volume between them — exactly the kind of concentration that invites regulatory attention rather than deflecting it.

I'm less confident than I'd like to be about how durable this particular growth engine remains over the next five years. The Federal Trade Commission's 2024 interim report on PBM practices was pointedly critical of spread pricing and formulary rebate structures, and several state attorneys general have opened their own inquiries since. None of that has changed the economics yet. But 'yet' is doing real work in that sentence, and an investor underwriting Optum's or Evernorth's growth rate on a ten-year view should have a view on regulatory risk, not just on prescription volume.

Regulatory Capture vs. Regulatory Risk

Managed care sits at an unusual intersection of two regulatory dynamics pulling in opposite directions, and conflating them is a common analytical mistake.

On one side is something close to regulatory capture: Medicare Advantage's risk-adjustment system pays insurers more for members coded as sicker, and insurers have considerable influence — through chart-review programs and provider incentives — over how thoroughly those diagnoses get documented. CMS has tightened the risk-adjustment model repeatedly, but insurers helping design the coding infrastructure that CMS is regulating creates a structural advantage that looks less like arm's-length oversight than industry participants shaping their own scoring system. On the other side is genuine regulatory risk cutting against the industry: CMS's annual Medicare Advantage rate notices have trended toward tighter reimbursement growth since 2023, state Medicaid programs are auditing MLR compliance more aggressively post-redetermination, and DOJ and FTC scrutiny of PBM practices sits squarely in this second camp. Same sector, sometimes the same regulators — a favorable dynamic in risk adjustment running alongside an adversarial one in pharmacy oversight, simultaneously.

Secular Tailwind, Cyclical Headwind

Two forces are working against each other in this sector right now, and mistaking one for the other is the most common error retail investors make in healthcare. The demographic force is essentially uncontroversial: the US population over 65 is the fastest-growing age cohort, and — as we've covered in how aging populations affect healthcare stocks — that cohort drives a disproportionate share of Medicare Advantage enrollment growth, the single largest profit pool in managed care. That demand curve isn't cyclical. It's baked into population math for the next two decades regardless of what happens to rates or the broader economy.

The near-term drag is utilization. Medical cost trend accelerated faster than most insurers priced for in 2023 and 2024, as deferred elective procedures from the pandemic years worked back through the system and outpatient volumes ran hotter than actuarial assumptions built a year in advance. Every major insurer beat or missed guidance on medical cost trend during that stretch, and the ones managing it best are the ones with genuine scale in claims data and provider-network leverage — an efficient scale advantage smaller regional plans can't replicate. Add the Medicaid redetermination unwind, which cost Centene and its peers millions of members as states re-verified eligibility after the pandemic-era continuous enrollment requirement lapsed, and you get a sector where the long-run demand story is unambiguous and the near-term earnings path is genuinely choppy.

None of this is unique to managed care. It's the general pattern in any regulated industry moat: the wall that protects incumbents from new entrants is the same wall that hands the government leverage over pricing and reimbursement whenever budgets tighten. Managed care investors are underwriting both sides of that wall at once, whether they realize it or not.

Key Takeaways

• The 85% (large-group/Medicare Advantage) and 80% (individual/small-group) MLR floors cap margin as a percentage of premium, not absolute profit. Insurers grow profit dollars by growing premium volume and by building revenue lines like PBM and care-delivery services that sit outside the rule entirely.
• The five largest public managed care companies split into three competitive roles, not five interchangeable insurers: scale incumbents (UnitedHealth, Elevance) competing on breadth, diversified challengers (Cigna, Humana) with opposite risk concentrations, and a Medicaid specialist (Centene) whose focus is a moat in normal periods and a liability during redeterminations.
• PBM vertical integration — Optum Rx, Evernorth, CarelonRx — is the industry's most consequential growth engine and its most exposed regulatory target simultaneously. FTC scrutiny of spread pricing is a real risk to a business line insurers have built entire growth narratives around.
• The sector combines a genuine secular tailwind (population aging, driving Medicare Advantage enrollment for two decades) with real cyclical and regulatory headwinds (medical cost trend, Medicaid redetermination, MA rate pressure). Treating either force as the whole story misreads the sector.