Bill Gates, who became the world's wealthiest person in the 1990s as Microsoft's value pushed his net worth beyond $100 billion, now has 78% of his foundation's $34 billion portfolio invested in four stocks. The Gates Foundation trust fund, which Gates plans to donate 99% of his wealth to over his lifetime, holds most of its portfolio in companies focused on finance and industrials rather than tech. The largest holding is Berkshire Hathaway at 24.6% of the portfolio, maintained despite stipulations that the foundation must spend the entire value of Warren Buffett's donation plus 5% of the rest of its endowment; Buffett stepped down as CEO at the start of the year, handing control to Greg Abel, who oversaw acquisitions of OxyChem and Taylor Morrison, and net earnings increased in each of Berkshire's core operating segments in the first quarter. The second largest position is Caterpillar at 18.3%, driven by price appreciation from its potential to participate in massive data center build-outs of big tech companies.