7. UnitedHealth Group (NYSE:UNH)
Ken Griffin’s Stake Value: $966,674,647
With a 15% share of the total U.S. insurance market and over 47 million members and growing, UnitedHealth Group (NYSE:UNH) remains the top beneficiary of key demographic factors in the US. What are they? 10,000 baby boomers age into Medicare every single day. By 2030, 20% of all Americans will be over 65. UnitedHealth Group (NYSE:UNH) sits directly in the path of this wave.
Optum, UnitedHealth Group’s (NYSE:UNH) healthcare services and technology business, is one of the biggest catalysts for the stock. While the insurance arm collects premiums and pays claims, Optum generates recurring fee-based revenue with data analytics, pharmacy services, and care delivery. This is what transforms UnitedHealth Group (NYSE:UNH) from a low-margin insurer into a healthcare technology compounder. UNH ranks seventh in our list of the best stocks to buy now, according to billionaire Ken Griffin.
Bretton Fund stated the following regarding UnitedHealth Group Incorporated (NYSE:UNH) in its fourth quarter 2025 investor letter:
“The main hit to the fund this year was UnitedHealth Group Incorporated (NYSE:UNH), impacting performance by -1.1%, when health costs for its enrollees surged unexpectedly. UnitedHealth had a disastrous 2025. The year began with a leak in February that the Department of Justice had launched an investigation into the company’s Medicare Advantage (MA) coding practices. In March, it actually won an MA coding case dating back to the Obama Administration, but it was a good reminder that investigations are easier to start than to win.
In April, the floor gave way. UnitedHealth announced that its membership, both on the insurance side and on its Optum healthcare services side, turned out to be far sicker and more expensive to treat than the firm had anticipated. The health insurance business is a low margin business that depends on actuarial accuracy: tiny changes in medical loss ratio have a tremendous impact on profitability. In May, UnitedHealth replaced then-CEO Andrew Witty with former CEO Stephen Hemsley, which confirmed that the errors were not the result of a fluke month of bad luck, but reflected poor modeling that would take some time to resolve. By August, the stock that had begun the year at $510 was trading below $240. Hemsley focused on shedding unprofitable customers and righting the ship, and while he said it would take much of 2026 to get back on track, the earnings potential of the franchise was compelling…” (Click here to read the full text)
