Editor's note: This article has been corrected. It is the Gates Foundation Trust that manages the endowment assets of the Gates Foundation and holds stock.

Judging by the disclosed holdings in the Gates Foundation Trust (formerly called the Bill & Melinda Gates Foundation Trust), one would think that billionaire Bill Gates is a big fan of Warren Buffett. According to the latest 13F filing of the trust, which manages the endowment assets of the foundation run by Gates, it owns a huge amount of Buffett's holding company, Berkshire Hathaway (BRK.A -0.02%) (BRK.B 0.07%).

The Gates Foundation Trust owns billions in Berkshire Hathaway stock

Right now, the largest stock position in the $46 billion trust's publicly disclosed portfolio is Microsoft. Gates co-founded Microsoft back in 1975 and in 2010 he committed to donating his entire stake in Microsoft to charity by the time he died. As a result, much of the foundation's holdings in Microsoft came from Gates' donations over the years. Today, the trust's stake in Microsoft is valued at around $15.4 billion.

Berkshire Hathaway, meanwhile, is the third-largest position in the trust's portfolio at around $7.3 billion. Most of those Berkshire shares were donated to the foundation by Buffett.

After Gates committed to donating the majority of his wealth to charity more than a decade ago, Buffett immediately joined him in making a similar pledge. A trust was launched in 2000 and was initially run by Gates, his now ex-wife Melinda French Gates, and Buffett. Together, the trio convinced dozens of other billionaires to also donate the majority of their wealth to various charitable causes. Buffett served as a member of the foundation's board until June 2021. Melinda Gates resigned from the board effective June 2024. Since 2021, Buffett started donating portions of his Berkshire stock to other charitable trusts instead, including trusts run by his three children.

While Berkshire Hathaway stock trades at all-time highs, the foundation trust's stake has shrunk in recent quarters (the sale is partly related to stipulations for how the donated stock must be used by the trust). Last quarter, for example, it trimmed its stake by 2.6 million shares -- a reduction of around 13%. However, don't expect it to disappear from the portfolio completely anytime soon. There are still plenty of funds left to utilize for charitable causes.