The Bill & Melinda Gates Foundation's $33 billion publicly traded U.S. stock portfolio is heavily concentrated, with 60% invested in three companies: Berkshire Hathaway, Canadian National Railway (CNI), and WM (formerly Waste Management). Berkshire Hathaway is the largest position, partly due to Warren Buffett's annual donations of its Class B stock. The foundation also holds significant stakes in Canadian National Railway, which reported an 11% year-over-year revenue increase in Q2 despite trade headwinds, and WM, a leading waste collection company known for its competitive advantage from landfills.