John Rex was the Chief Financial Officer (CFO) of UnitedHealth Group, a role he held from 2016 to 2025. In July 2025, UnitedHealth announced that Wayne DeVeydt would become chief financial officer effective September 2, 2025, and John Rex moved into a strategic adviser role to the chief executive officer. Rex had also taken on the role of president in April 2024, succeeding Dirk McMahon. As CFO, Rex oversees an expansive operating, growth, and finance portfolio, including technology and digital strategies, treasury, mergers and acquisitions, and venture and private equity investment activity.
Rex has had a successful career in finance, previously serving as executive vice president and CFO of Optum, UnitedHealth Group’s health services business. He’s also worked as a leading equity research analyst, strategy and operational consultant, and certified public accountant across various healthcare sectors.
As a prominent figure in the healthcare finance industry, Rex’s leadership and expertise have been instrumental in shaping the financial strategy of UnitedHealth Group.
From CFO to strategic advisor
Rex’s long run as UnitedHealth’s finance chief came to an end in 2025. In July of that year the company announced that Wayne DeVeydt, who had previously served as chief financial officer of Elevance Health from 2007 to 2016 and most recently as a managing director at Bain Capital, would take over as CFO effective September 2, 2025. Rex, who had held the CFO chair since 2016, moved into a strategic advisor role to the chief executive officer. The handoff closed a nine-year tenure in which Rex guided the finances of the largest health insurer in the United States through an acquisition spree, the Change Healthcare cyberattack of 2024, and mounting pressure on Medicare Advantage margins.
Rex’s road to the top
Rex arrived at UnitedHealth in 2012 as executive vice president and chief financial officer of Optum, then the company’s newly established health services arm. Four years later, in June 2016, he was elevated to CFO of the parent company. In April 2024 he added the title of president, succeeding Dirk McMahon, who retired after more than two decades with the company.
Before UnitedHealth, Rex spent more than a decade in financial services. He worked as a senior research analyst at Bear Stearns, a senior analyst at J.P. Morgan Securities, and ultimately a managing director at J.P. Morgan, alongside earlier stints in strategy consulting and as a certified public accountant. He holds an undergraduate degree from Brigham Young University and an MBA from the Wharton School of the University of Pennsylvania.
Investors had reason to watch him closely. As CFO he oversaw treasury, mergers and acquisitions, and venture and private equity activity, plus the enterprise’s technology and digital strategy, during a period when UnitedHealth was aggressively expanding Optum through deals like the $5.4 billion acquisition of LHC Group. In 2022 he was the company’s second-highest-paid executive, with total compensation of $15.8 million.
The $22 Million Ransom: The CFO in the Middle of a Cyberattack
On February 21, 2024, ransomware gang ALPHV/BlackCat struck Change Healthcare, the claims-processing giant UnitedHealth had acquired in October 2022. The hackers had slipped in nine days earlier through a remote-access portal protected only by stolen credentials, with no multifactor authentication turned on. They shut down claims processing nationwide, freezing payments to pharmacies, hospitals, and doctors’ offices. On May 1, 2024, CEO Andrew Witty told Congress the company had paid a $22 million Bitcoin ransom, calling it “one of the hardest decisions I’ve ever had to make.” Rex, who oversaw treasury, risk management, and the enterprise’s technology strategy, sat at the center of the response. The episode is a reminder of what a modern health-insurer CFO actually manages: not just the balance sheet, but the company’s worst week. UnitedHealth later estimated the attack affected a substantial proportion of Americans’ records, and Congress called the breach a national security threat.
The Medicare Advantage Squeeze He Was Navigating
Rex’s final years as CFO were dominated by pressure on Medicare Advantage, the government-backed senior health plans that are UnitedHealth’s largest business. Rising medical costs collided with tighter government payment rates, squeezing the margins on the plans millions of retirees depend on. Managing that squeeze, while funding the Optum acquisition spree and absorbing the Change Healthcare fallout, was the defining test of his tenure. For readers trying to understand how Medicare actually reaches seniors, the connection is direct: the financial health of insurers like UnitedHealth shapes the benefits and premiums retirees see every year.
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