The U.S. Healthcare
Stack
How a small number of corporations came to control the insurance, the pharmacy benefits, the pharmacies, and increasingly, the care itself.
This is a map of vertical integration. It shows how the same companies that decide what your insurance covers also manage your prescriptions, fill them, and now want to be your doctor too.
American healthcare is not merely expensive. It is increasingly concentrated.
Over the past two decades, a small number of corporations have quietly assembled control across multiple layers of the healthcare system. The same company that provides your health insurance may also manage your pharmacy benefits, operate the pharmacy that fills your prescriptions, and run the clinic where you see a doctor.
This is not an accident. It is a business strategy called vertical integration. The theory is that owning multiple parts of the healthcare supply chain creates efficiencies. The reality is more complicated.
“When the same company can touch the plan, the formulary, the pharmacy, the data, and increasingly the care itself, control compounds.”
Integration creates leverage. A company that owns both a pharmacy benefit manager and a pharmacy can steer prescriptions to its own counters. A company that owns both an insurer and a network of doctors can direct patients to its own clinics. A company with visibility into claims data, prescriptions, and medical records can optimize for its own financial benefit in ways that are difficult for patients, employers, or regulators to see.
The map below is not just about scale. It is about structural power. It shows how ten corporations have positioned themselves across insurance, pharmacy benefits, retail pharmacy, specialty pharmacy, care delivery, home health, distribution, diagnostics, and health technology.
Each layer represents an opportunity to extract margin. Each connection represents influence over how care is financed, approved, routed, and delivered.
U.S. national health expenditures reached $5.3 trillion in 2024. The conglomerates mapped here sit at the center of this system—not as providers of care, but as the intermediaries who decide what gets covered, what it costs, and where patients can go.
How the Stack Was Built
The current healthcare landscape did not appear all at once. It was assembled in layers, through years of strategic acquisitions and corporate combinations.
First, the rails were built. PBMs consolidated. Retail pharmacies expanded. Distribution companies moved into specialty care. Then, in a more visible wave, insurers merged with PBMs and began acquiring the care itself.
What follows is the story of how a fragmented industry became a corporate system.
Foundations of Consolidation
The Rails Were Built
Before the headline-grabbing mega-mergers of the late 2010s, the groundwork was being laid. PBMs consolidated. Retail pharmacies expanded into care. Distributors moved deeper into provider networks. These were the rails upon which later integration would run.
CVS acquires MinuteClinic
An early move into care delivery inside the retail pharmacy footprint. The pharmacy counter becomes a site of clinical care.
CVS acquires Caremark
A major stack-building moment. Retail pharmacy combines with pharmacy benefit management. One company now touches both the dispensing and the formulary.
McKesson acquires US Oncology
Distribution moves into specialty provider networks. The line between logistics and care begins to blur.
Express Scripts acquires Medco
A major consolidation in the PBM layer. Two of the largest pharmacy benefit managers become one.
CVS expands through Omnicare, Coram, and Target pharmacies
A rapid expansion across specialty infusion, long-term care pharmacy, and retail footprint. The stack grows wider.
OptumRx acquires Catamaran
UnitedHealth strengthens its PBM position. The insurer now has a more robust pharmacy benefits arm.
The groundwork had been laid. The rails were in place. Now the strategy would become unmistakable: own every layer the patient touches.
Full-Stack Expansion
The Strategy Becomes Visible
The quiet assembly gives way to unmistakable integration. Insurers combine with PBMs. Care delivery becomes a corporate priority. Home health enters the portfolio. By the early 2020s, the strategy is no longer subtle: own every layer the patient touches.
CVS Health completes acquisition of Aetna
Pharmacy, PBM, and insurer under one roof. A defining moment in healthcare consolidation. The full stack begins to crystallize.
Cigna completes combination with Express Scripts
Another insurer absorbs a PBM. The pattern becomes unmistakable. Vertical integration is now the dominant strategy.
Optum completes acquisition of DaVita Medical Group
UnitedHealth moves deeper into direct care delivery. The insurer now employs physicians and operates clinics.
Humana acquires remaining stake in Kindred at Home
A significant expansion into home health. Care moves beyond the clinic and into the living room.
Optum completes combination with Change Healthcare
The data layer is claimed. Claims, payments, and infrastructure now flow through the same corporation that insures and treats patients.
CVS completes acquisition of Signify Health
Home-based care and provider enablement enter the CVS portfolio. The reach extends into where patients live.
CVS completes acquisition of Oak Street Health
Primary care at scale. CVS now operates value-based clinics focused on Medicare patients. The stack is nearly complete.
This is how the stack was built. Layer by layer. Acquisition by acquisition. Now, see what the finished system looks like.
Revenue figures from official FY2025 earnings reports. PBM market share from industry analysis.
Combined Annual Revenue
These ten conglomerates generate over $2 trillion in annual revenue, representing a significant portion of U.S. healthcare spending. Click the chart to explore each conglomerate and their subsidiaries.
Revenue figures from official FY2025 earnings reports. Click a company to explore its subsidiaries.
See how much one company controls
Hover over a conglomerate to reveal its reach across the healthcare system. Each highlighted cell represents a sector where that company has positioned itself to influence cost, access, or care delivery.
Hover over a conglomerate to highlight its presence. Click for details.
How vertical integration compounds control
Owning multiple layers of the healthcare system is not just about scale. It creates structural power that shapes how care is financed, approved, routed, and delivered.
Insurer + PBM
When an insurer owns the pharmacy benefit manager, it controls both what drugs are covered and how much pharmacies get paid for dispensing them.
The company profits from both premium collection and PBM fees, with limited external oversight of formulary decisions.
PBM + Pharmacy
When a PBM owns pharmacies, it can steer prescriptions to its own stores while setting reimbursement rates for competitors.
Independent pharmacies face rates set by a direct competitor. Mail-order prescriptions are often routed to captive pharmacies.
Insurer + Care Delivery
When an insurer owns clinics and employs physicians, it can direct patients to its own providers and influence treatment decisions.
The company that pays for care also delivers it. Cost containment and clinical judgment can become difficult to separate.
Full Stack Control
Some conglomerates now span insurance, PBM, pharmacy, and care delivery all at once, touching nearly every step of a patient's healthcare journey.
A single corporation can approve your coverage, manage your prescriptions, fill them, and increasingly be your doctor too.
“Integration is not inherently bad. But when the same company that approves your treatment also profits from steering it, the patient is not the only one being optimized for.”
What concentration means for patients
This system was not designed with affordability as its primary goal. The structure itself shapes what is possible.
Rising Costs
Healthcare spending continues to grow faster than inflation, with more margin captured at each layer of the system. Integration was supposed to create efficiencies. Prices suggest otherwise.
Opaque Pricing
When a company operates the PBM, the pharmacy, and the insurer, there are internal transfers that patients, employers, and regulators cannot easily see. Rebates, spreads, and fees flow between related entities.
Limited Leverage
Patients have little negotiating power in a system where choices are increasingly constrained. Network restrictions, formulary decisions, and prior authorization requirements are set by companies that profit from the friction.
Captured Margins
Each layer of the stack represents an opportunity to extract value. When a single company controls multiple layers, it can optimize margin capture across the entire patient journey.
Complexity as Feature
The system & complexity is not a bug. It benefits institutions that can navigate it while leaving patients, employers, and small providers struggling to understand where money actually goes.
Misaligned Incentives
When the same company profits from covering care, managing benefits, filling prescriptions, and delivering treatment, whose interests are being optimized? The answer is not always the patient.
“The question is not whether these companies are efficient. It is whether the system they have built serves the people who depend on it or the shareholders who own it.”
The issue is not simply that American healthcare is expensive. It is that more of it is being controlled by fewer companies. And those companies are increasingly positioned to profit from multiple points in the same patient journey.
This visualization is not an argument against all integration or consolidation. It is an attempt to make visible the structure of a system that most people navigate without understanding who controls what. Transparency is the first step toward accountability.