Toyin Ajayi: Building the Healthcare Infrastructure Behind Medicaid

Executive Summary

Toyin Ajayi is a physician, the co-founder and chief executive of Cityblock Health, and the person who has steered it since March 2022. That biography invites the obvious reading: a doctor who built a health company. The more productive reading, and the one this article argues, is that Ajayi built coordination infrastructure around a population that conventional systems struggle to coordinate: people enrolled in Medicaid, and in particular those who are dually eligible for Medicaid and Medicare. The word infrastructure is The Upside Journal's lens, not Cityblock's own. This article states the evidence for the reading, the limits of that evidence, and what the model shows about where healthcare value is built.

Introduction: A Healthcare Founder, or an Infrastructure Operator?

Describing Ajayi as a healthcare founder is accurate and incomplete. The category suggests a product, a clinic or an app. What she leads is closer to a system that sits between government health programmes, the health plans that administer them and the members who rely on them. Its output is not a single service but the connection of services that otherwise do not talk to one another.

This article treats her work the way an operator would. It asks what problem she identified, why an infrastructure approach was needed to address it, what Cityblock built, how that changes care delivery and why the model matters beyond one company. It does not walk through Cityblock's operating model in detail, argue the structural case for Medicaid as an infrastructure problem or extract repeatable operating principles. Those are separate nodes in this cluster.

One point of terminology comes first. Cityblock's own description, in its August 2026 release on a North Carolina expansion, is: "Cityblock is a healthcare provider — doctors, nurses, and community teams delivering hands-on care and support designed for the most complex, hardest to reach populations." The word infrastructure does not appear in that sentence. It is the framing this publication applies, and the sections below argue for it rather than assume it.

Who Is Toyin Ajayi?

Ajayi is a board-certified family medicine physician. Before Cityblock she served as chief medical officer of Commonwealth Care Alliance, a role cited in the company's March 2022 release announcing her appointment as chief executive. Cityblock was founded in 2017, out of Alphabet's Sidewalk Labs, by Ajayi and Iyah Romm, according to Fierce Healthcare's report on her appointment, and she took over the chief executive role in March 2022.

On her origins, a single source is available. Billionaires.Africa reported on 29 June 2026 that she was "born to Nigerian parents." The wording rests on that one report, and this article does not extend it. What matters for the argument is the professional trajectory: a clinician who moved from leading medical strategy at an organisation serving people with complex needs to building a company designed around them.

The profile also fits the wider cluster. The diaspora operators thesis explains why founders who work across more than one system often see seams that others treat as given. That argument is made there, and this article applies it only as a lens.

What Problem Did Ajayi Identify?

The problem is one of coordination at scale. The Kaiser Family Foundation's enrolment tracker reports 73.2 million people enrolled in Medicaid and the Children's Health Insurance Program as of June 2026, a figure KFF marks as preliminary. Within that population, a smaller group concentrates both need and cost. About 12 million people are dually eligible for Medicaid and Medicare, and KFF's analysis of 2023 data puts them at 13 percent of Medicaid enrolment but 30 percent of Medicaid spending, or $241 billion of $796 billion. MACPAC, the statutory advisory commission, reported in February 2026 that spending on dually eligible beneficiaries exceeds $200 billion.

Concentration of cost is an old finding. A 2015 Government Accountability Office report found that the most expensive five percent of Medicaid-only enrollees accounted for almost half of that group's spending. That figure is a decade old and is cited only to show that the pattern predates the current period.

Cost concentration says something about need as well. Fierce Healthcare reported on 13 January 2026 that 86 percent of Cityblock's members are Medicaid or dually eligible, that more than 8 in 10 have more than two chronic conditions and that 6 in 10 have a behavioural health need. The article does not name the source of those figures, so they are cited as reported. They describe the population Ajayi built around: people whose needs span clinical, behavioural and social domains that are usually served by different organisations.

The problem she identified, in the infrastructure reading, is that no single party in the conventional system is responsible for the whole person. A verdict follows from that. A population that requires several systems to act together does not need a better clinic; it needs the connection between them.

Why Did Medicaid Require an Infrastructure Approach?

The analytical formula for any defined concept runs from what it says, to what it means, to who benefits and what economic consequence it creates. Applied to coordination: what it says is that care is delivered across clinical, behavioural and social settings. What it means is that someone must hold the thread. Who benefits are members, whose needs are met in sequence rather than in fragments, and the plans and governments that pay for outcomes. The economic consequence is that cost is determined less by any single service than by how well services work together.

An infrastructure approach follows from that consequence. Infrastructure, in the sense used across this publication, is a layer that other parties build on and rely on, and whose value is realised in the connections it makes possible. A health plan that contracts for care coordination for a defined population is buying a layer, not a clinic visit.

Cityblock's contracting pattern is consistent with that reading. In January 2026, Cityblock and Meridian Health Plan of Illinois announced a partnership to serve 10,000 Medicaid members. The company's releases also describe partnerships with national and regional Medicaid plans and health systems. A pattern of plan partnerships does not prove the infrastructure claim, but it shows where Cityblock sits: between the payer and the member.

The reading has limits, which the final sections address. The strongest form of the argument is not that Medicaid is a technology problem, but that it is a coordination problem that rewards organisations built to hold the thread.

What Did Cityblock Build?

At the level this article covers, Cityblock built an organisation that delivers hands-on care to Medicaid, Medicare and dually eligible members under contracts with health plans and health systems. Its scale is reported by the company. In a byline published on 3 September 2026 in Healthcare IT Today, Ajayi wrote that Cityblock serves almost 200,000 members. That is a company-reported figure, so it should be read as a point in time and not as a series.

Geographic growth shows the same pattern. On 13 August 2026, Cityblock announced an expansion in North Carolina to support nearly 20,000 dual-eligible and Medicare Advantage members, effective 1 July 2026. A week later, on 20 August 2026, the company announced a $116 million Series E led by General Catalyst alongside an all-stock acquisition of Homeward Health, reported by Fierce Healthcare and HIT Consultant. The round's valuation was not disclosed, and this article does not state a cumulative funding total, because the published totals differ in date and scope.

The Homeward acquisition is worth noting for what it implies about the model. An infrastructure layer extends by adding coverage, whether by geography, programme or member type. The company announced an expansion and an acquisition within a week of one another.

What the evidence supports is that Cityblock is a scaled organisation with plan partnerships across several states, whose self-reported membership has grown. What it does not support is a claim about profitability or returns, because the sources reviewed for this article do not provide audited figures.

How Does That Change Care Delivery?

The test of any coordination claim is whether outcomes or costs change. Published evidence reviewed for this article is limited and should be read as such. Behavioral Health Business reported in November 2024 on a study published in NEJM Catalyst, which found an 11.5 percent decrease in total cost of care for a behavioural health arrangement. The sample was 123 members. A result at that size cannot be generalised to Cityblock's membership or to Medicaid broadly, and it is cited here only to show the form that evidence takes.

A second strand is Ajayi's own argument about priorities. HIT Consultant reported on 25 March 2026 that she argued the healthcare industry's AI investment is skewed toward billing and revenue cycle management, and that it should be directed toward care delivery for complex populations. This is a position, not a finding, and it shows how she frames the product: technology is a means of extending the coordination layer.

The change in care delivery, as far as the published record shows, is a shift in the unit of responsibility. Instead of a series of encounters in which each provider sees one part of a member's needs, a coordinating organisation holds responsibility for the whole. Whether that shift improves outcomes at scale is an empirical question that the sources reviewed do not settle.

The verdict for this section is that the model's evidence is promising in form and thin in size, and a careful reader should hold both facts together.

Why the Model Matters Beyond One Company

The significance of the model is comparative. Across the diaspora operator cluster, founders have built layers in sectors where fragmented systems impose costs on the people who depend on them. The profile of Iman Abuzeid addresses healthcare workforce supply, which is a different mechanism within the same sector: there the layer matches clinicians to demand, while Ajayi's layer coordinates care for members once demand exists. The two pieces describe different parts of the same system.

The structural pattern is also visible outside healthcare. Abbey Wemimo's work on turning rent into credit builds around a data gap that conventional systems left open. Tobenna Arodiogbu's trucking infrastructure serves a fragmented market of small operators. Ridwan Olalere's LemFi connects financial systems across borders. In each case, the founder built a layer where a population fell between institutions.

What distinguishes Ajayi's version is the population. Medicaid members are served by a public programme whose rules, funding and administration sit with governments and plans, so the layer must be built with, not around, those institutions. In this reading, that constraint is also a source of the model's durability, because plan contracts and programme relationships take longer to replicate than a software feature.

The model matters because it shows that infrastructure can be built around people as well as around technology, and that the institutions in the way are part of the design.

What the Model Asks of an Operator

An Operator profile earns its place by changing what a reader does on Monday morning. Ajayi's model does not supply a playbook, which belongs to a later piece in this cluster, but it does put three questions to any leader running a service for people who sit between institutions.

The first is who holds the thread. In most multi-party services, each organisation is accountable for its own step and no one is accountable for the sequence. A leader can test this by asking who would notice, and who would act, if a member's needs were met by three providers in an order that left a gap. Where the answer is no one, a coordination layer is missing, whether or not anyone calls it infrastructure.

The second is who pays for the connection. Cityblock's contracts with health plans suggest that the party with the financial exposure, the plan, is the natural buyer of coordination. An operator building in a different sector should identify the equivalent party: the one whose costs rise when the connection fails.

The third is what evidence the buyer will require. The one outcomes result reviewed for this article rests on 123 members, which is enough to attract a pilot and not enough to settle a contract renewal at scale. A leader who wants durable contracts should plan to produce evidence at the size the buyer needs, and to state its limits plainly when it is smaller.

Each question is a test of whether a service is a product or a layer, and the answers decide which of the two a founder is actually building.

Where the Claim Stops

An honest assessment states where the infrastructure reading is weakest. First, it is a lens. Cityblock describes itself as a care provider, and the infrastructure framing is an interpretation that readers may accept or reject. Second, the company's scale and membership figures are self-reported, and they are not audited. Third, the one outcomes figure reviewed for this article rests on 123 members.

Fourth, the sources reviewed give no valuation for the August 2026 round and published funding totals differ in date and scope. This article therefore draws no conclusions about financial performance. Where sources conflict, such as on member counts across 2026, the article uses a single dated figure and says so.

The reading holds as an analytical frame because the activities it describes, plan contracts, programme expansion and population-level coordination, are the activities of a layer rather than of a single clinic. It does not hold as a claim that the layer has been proven to improve outcomes at scale.

Why This Matters for Healthcare Operators and Capital Allocators

For healthcare operators and health plan executives, the question is where coordination responsibility should sit. A plan that contracts for coordination for a defined population is making an infrastructure decision. The evidence suggests that these arrangements are growing, but a plan should require outcome reporting and sample sizes that support the claims made for them.

For founders in adjacent sectors, the model illustrates how to approach a fragmented market: identify the population that falls between institutions, then build the connective layer and contract with the institutions that pay. For investors and allocators, the relevant questions are whether coordination revenue is durable, how it depends on programme rules and what evidence of outcomes the company can publish. The $116 million round shows investor interest, but the undisclosed valuation limits what can be inferred.

Key Takeaways

• Ajayi is best read as an infrastructure operator: the label is The Upside Journal's lens, and the evidence is a company that coordinates care for Medicaid and dually eligible members under plan contracts.
• The problem is coordination, not capacity: dually eligible people are about 13 percent of Medicaid enrolment and 30 percent of its spending, per KFF's 2023 data.
• Cityblock's scale is company-reported: Ajayi wrote in September 2026 that it serves almost 200,000 members, and its expansion and acquisition show how a coordination layer extends.
• The outcomes evidence is small: the 11.5 percent cost reduction rests on 123 members and cannot be generalised.
• The model's durability is institutional: in this reading, plan contracts and programme relationships take longer to replicate than a software feature.

Conclusion

Toyin Ajayi's significance lies in building infrastructure around a Medicaid population that conventional systems struggle to coordinate. The evidence for that reading is the company's contracting pattern, its reported scale and its expansion, and the evidence against overreading it is the limited published outcomes data and the self-reported nature of its figures.

The reading is useful because it moves the question from whether Cityblock is a good clinic to whether coordination is a layer worth building and funding. On the available evidence, it is a layer that is being built, with institutional partners, at growing scale. Whether it proves its value in outcomes is the question the next stage of reporting will need to answer.