Toyin Ajayi raised $891 million to fix American healthcare for the people everyone else gave up on

Toyin Ajayi grew up in Nairobi watching her father work. He was a general physician navigating the AIDS epidemic in East Africa, a period defined by overwhelming need and inadequate resources, and she would follow him to the hospital he supervised and watch what he did there. What she absorbed was not simply the science of medicine. It was something about systems. Who got care and who did not. Who the system was designed to serve and who it had simply decided to leave behind.

Her parents were deliberate about it. They raised Ajayi and her two younger sisters to understand that their own economic security and good health came with a responsibility to help others less fortunate. When she was in her late teens, they took her to volunteer at an organisation that served women dying of AIDS. She saw the disease take people who looked like her. She remembers, decades later, the precise moment she watched a news segment debating whether it was cost-effective to send antiretroviral treatments to people in Africa. "I just remember feeling so angered and indignant and determined that that was not the way that we as a society should think about the allocation of resources," she said.

She channelled that anger into medicine. And medicine, eventually, led her to build a company that has raised $891.3 million to deliver healthcare to the people the American system has historically decided are too poor, too sick and too complicated to bother with properly.

Her name is Dr. Toyin Ajayi. She is the co-founder and CEO of Cityblock Health, valued at approximately $6 billion. She is also still, after everything, a practicing doctor.

Nairobi to Stanford to the world

Ajayi was born to Nigerian parents and raised in Kenya, which gave her an early and visceral education in what healthcare inequality actually looks like when you are close enough to see it. Her father's work during the AIDS epidemic, specifically his efforts to improve maternal health in a region where resources were chronically inadequate, gave her both a model and a problem. She had no intention of simply inheriting his profession. She wanted to fix what he had spent his career navigating around.

Her academic path reflected that ambition. She completed her undergraduate degree in human biology at Stanford University, a subject that sits precisely at the intersection of science and the social forces that shape human health outcomes. From Stanford she went to the University of Cambridge, where she earned an MPhil in Development Economics and International Development, a degree less about clinical medicine and more about understanding why some populations stay sick regardless of what the health system does for them. From Cambridge she went to King's College London School of Medicine, where she earned her medical degree with Distinction in Clinical Practice. She completed her residency in family medicine at Boston Medical Center, then stayed on as an attending physician in the Department of Family Medicine and a clinical instructor at Boston University School of Public Health.

The academic credentials were extraordinary. But Ajayi has always been more interested in systems than in her own resume, and the experience that shaped her most sharply did not happen in a lecture theatre.

Sierra Leone

In 2009, while still in the early stages of her medical career, Ajayi went to Freetown, Sierra Leone, and started a nonprofit focused on improving healthcare at the capital's largest safety-net hospital. She was one of approximately 50 doctors serving a country of 7 million people. What she found there was, in her own word, needless death. Patients dying not because the medical knowledge to save them did not exist, but because the systems needed to deliver that knowledge to them had never been built. She set about building the beginning of them, improving relationships between the hospital and the communities it was supposed to serve and learning in the process the thing that would define everything she built afterward.

The lesson of Sierra Leone was not about individual doctoring. It was about system design. She could be an excellent physician and still be overwhelmed by the structural failures around her. The problem was not the quality of the medicine. The problem was the architecture of delivery. "I wanted to build systems," she said. Not clinics. Systems.

She came back from West Africa with that understanding embedded. Whatever she built next was going to be about changing the infrastructure, not just the clinical quality of individual encounters.

Boston and the education that mattered most

Back in the United States, Ajayi joined Commonwealth Care Alliance in 2013 as Hospital Medical Director and Director of Transitions of Care, a role that put her inside one of the country's most closely watched experiments in integrated care for Medicaid and dual-eligible populations. By 2015 she had risen to Chief Medical Officer, leading clinical operations, managing multidisciplinary teams of more than 500 clinicians, community health workers and administrators, and overseeing programmes that served more than 20,000 recipients across Massachusetts.

It was at Commonwealth Care Alliance that two things happened that would determine the rest of her professional life. The first was that she spent years learning, with uncommon granularity, how care for the most complex patients is actually financed, how actuaries think about these populations, and what the gap is between what the existing system pays for and what these patients actually need. The second was that she met Iyah Romm, who was working in Massachusetts state government on healthcare reform.

Together, they decided they had learned enough to build something different.

Building Cityblock

The idea they arrived at when they moved to New York in late 2017 was not complicated to state, though it turned out to be enormously complicated to execute. What if you took everything that made value-based care for Medicaid populations work, the trust-building, the home visits, the integration of behavioral health and social services with primary care, the community health workers who look like and live like the patients they serve, and built it at scale using technology to make the economics viable?

Most investors told them this was impossible. The Medicaid population was too complex. The margins were too thin. The reimbursements were too low. The churn was too high. No scaled venture-backed company had ever successfully served Medicaid populations and survived. "There had been no scaled venture-backed companies serving Medicaid populations because it's too hard," Ajayi recalled of the early pitch meetings.

The founders found their opening through Sidewalk Labs, the Alphabet subsidiary focused on urban innovation, which incubated Cityblock in late 2017 and provided space, technology resources and initial capital without the institutional scepticism that had greeted them elsewhere. The company spun out on its own and planted itself in Brooklyn, serving the kind of neighbourhood-level populations it was designed for. The co-founders alongside Ajayi and Romm were Bay Gross and Mat Balez, giving the founding team a blend of clinical, operational and technology expertise from the outset.

The first funding round of $20 million arrived in 2018 from Thrive Capital and Maverick Ventures. Then came $160 million in December 2020, $192 million in a Series C extension in March 2021, and approximately $400 million in a late-stage round later in 2021 that pushed the company's total to $891.3 million across 34 institutional investors, including Tiger Global, Wellington Management, General Catalyst, Goldman Sachs Asset Management, SoftBank and 8VC. The valuation reached approximately $5.7 to $6 billion. Revenue grew by a factor of eight in three years.

Ajayi served as president and chief health officer while Romm was CEO. In November 2021, Romm announced he was taking a leave of absence to focus on his mental health. Andy Slavitt, the former Obama White House senior adviser and acting administrator of the Centers for Medicare and Medicaid Services, stepped in as interim head while the board conducted a CEO search. Slavitt now chairs Cityblock's board. In March 2022, Ajayi was appointed CEO, taking over a company that had grown, including through the COVID-19 pandemic, into a genuinely national healthcare provider.

The model and why it matters

Cityblock operates across six markets in Indiana, Massachusetts, New York, North Carolina, Ohio and the Washington DC area, serving approximately 100,000 members. Three quarters of those members qualify for financial assistance. More than three quarters are members of a racial or ethnic minority group. The care model integrates primary care, behavioral health and social services, with community health workers and clinical teams operating out of neighbourhood hubs and also making home visits. Members can reach clinical support around the clock.

The company takes on financial risk from payers, meaning it absorbs the cost of poor outcomes rather than simply charging fee for service. The argument Ajayi has built her company around is that this population, the poorest and most structurally vulnerable people in America, is not only worthy of excellent care but represents a viable commercial opportunity if you invest upstream in prevention and trust-building rather than simply treating acute illness after it arrives. "The populations that we serve are worthy of very high quality and excellent care," she said. "This work is about proving that there is a sustainable and scalable business case."

The layoffs and the harder questions

The road to proving that case has not been smooth. In May 2023, Cityblock laid off 60 employees in Washington DC after the DC Council voted not to renew CareFirst BCBS as the district's managed care partner, removing a significant revenue source in one of the company's key markets. The following month, Ajayi announced a restructuring that resulted in a further 155 layoffs, 12 percent of the total workforce, framed as right-sizing the business for its next phase of growth.

Employee reviews during this period described a difficult internal environment: frequent reorgs, poor communication from senior leadership, burnout among frontline workers and high turnover. Some employees described two or three rounds of layoffs in a single year. Glassdoor and Indeed reviews noted leadership communication gaps, constant structural change and frustration at the illiquidity of employee equity in a company that remains private with no confirmed IPO timeline.

Ajayi was direct about the difficulty of those decisions. She framed the June 2023 restructuring as the natural maturation of a company whose growth had outpaced some of its internal infrastructure. The majority of the $891 million raised remained unspent, she noted, and the company was not being forced into cuts by an empty balance sheet. "Although it is always difficult to say goodbye to people who have been so important to the history and to the progress that the company has made, knowing that we're doing so from a position of strength as a business, from a balance sheet perspective, from a mission perspective, from an outcomes and performance perspective enables us to continue to grow," she said.

The deeper challenge, which Ajayi has acknowledged publicly, is that building a sustainable business around Medicaid is structurally hard in ways that a compelling mission does not resolve. Reimbursement rates are set by state governments. Payer contracts can be lost. The populations served are expensive to care for well. The metrics that determine whether the model works take years to generate, but investors and payers want evidence of cost savings on shorter timelines.

The recognitions and the work ahead

In 2021, Entrepreneur Magazine named Ajayi one of its 100 Women of Impact. In 2023, Time Magazine placed her on its TIME100 Next list of emerging leaders. The same year, the Black Business Ventures Association named her to its Founding 50 list of top-performing Black founders in tech. Also in 2023, she was named to Modern Healthcare's Top Women Leaders in Healthcare list, the STAT STATUS List and was selected as an Aspen Institute Henry Crown Fellow. She serves on the board of Evolent Health, a publicly traded healthcare company on the New York Stock Exchange, and on the board of the City University of New York. She is a member of the Congressional Budget Office's Health Panel of Health Advisers. She previously served on the board of the Boston Area Rape Crisis Center from 2017 through 2019.

She continues to practice medicine. In an industry full of healthcare executives who have not seen a patient in years, Ajayi has kept her clinical license active and continues seeing patients with chronic, complex and end-of-life needs. It is a choice, not an obligation, and she has described it as essential to understanding what the company she runs is actually delivering to the people it serves.

The girl who grew up in Nairobi watching her father navigate a broken system, who felt rage at a television set debating whether African lives were worth saving, who went to Sierra Leone and found needless death and decided to build something that addressed its root causes, is now the CEO of a $6 billion healthcare company trying to prove that the American system can be made to work for the people it has historically decided to leave behind.

She has raised $891 million betting that it can.