Billionaire Bill Gates Has 30% of His Foundation's $36 Billion Portfolio Invested in This Warren Buffett Stock

What's the largest holding in the Bill & Melinda Gates Foundation Trust's portfolio? Perhaps surprisingly, it isn't Microsoft (NASDAQ: MSFT). To be sure, the Gates Foundation Trust owns a hefty stake in the software giant that Gates co-founded. However, Microsoft ranks as only the fifth-largest position for the charitable organization.

The Gates Foundation Trust's largest holding is Warren Buffett favorite. And roughly 30% of its $36 billion portfolio is invested in this one stock.

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The quintessential Buffett stock

The stock in question isn't just any Buffett stock. I'd argue that it's the quintessential Buffett stock. I'm referring, of course, to Berkshire Hathaway (NYSE: BRK.A) (NYSE: BRK.B).

Buffett led Berkshire Hathaway for over six decades. Even though the legendary investor recently passed the baton to new CEO Greg Abel, he remains Berkshire's chairman. More importantly, he's still the conglomerate's largest shareholder.

However, the Gates Foundation Trust is also a major shareholder in Berkshire Hathaway. As of the organization's most recent 13F filing, it owned nearly 21.8 million shares of Berkshire, valued at more than $10.9 billion.

This stake was even higher. The Gates Foundation Trust sold 2.36 million shares of Berkshire in the third quarter of 2025, reducing its position by almost 9.8%.

Why is the Gates Foundation Trust so heavily invested in Berkshire?

Gates and Buffett have been friends for years. They played bridge together. Gates served on Berkshire's board of directors from 2004 to 2020. Buffett previously served on the Gates Foundation's board.

But this relationship isn't why the Gates Foundation Trust is so heavily invested in Berkshire Hathaway. The more likely reason is that the conglomerate's stock has been a reliable investment through the years.

Between 1964 and 2024, Berkshire Hathaway delivered an overall gain of 5,502%. This return translates to a compound annual growth rate of 19.9%. By comparison, the S&P 500's (SNPINDEX: ^GSPC) compounded annual gain during the same period was 10.4%. Granted, Berkshire lagged behind the S&P 500 last year. However, it has nonetheless been a solid investment for the Gates Foundation Trust.

Yes, Berkshire Hathaway is still a great stock to buy and hold

Is Berkshire Hathaway still a great stock to buy and hold? I think the answer is an emphatic "yes."

While Buffett is no longer at the helm, he's still active in the company. His philosophy still influences management's decisions.

Berkshire continues to generate strong free cash flow. Its wholly owned businesses and stakes in other publicly traded companies are diversified across multiple sectors and industries. Whether or not the conglomerate remains the largest holding in the Gates Foundation Trust's portfolio, it's worthy of a spot in the portfolios of ordinary long-term investors.

Keith Speights has positions in Berkshire Hathaway and Microsoft. The Motley Fool has positions in and recommends Berkshire Hathaway and Microsoft. The Motley Fool recommends the following options: long January 2026 $395 calls on Microsoft and short January 2026 $405 calls on Microsoft. The Motley Fool has a disclosure policy.