The top 10 stocks in the S&P 500 account for 40% of the index’s market cap. Since ChatGPT launched in November 2022, AI-related stocks have registered 75% of S&P 500 returns, 80% of earnings growth, and 90% of capital spending growth. Meanwhile, AI investments accounted for nearly 92% of the U.S. GDP growth this year. Without those AI investments, Harvard economist Jason Furman noted, growth would be flat. As Ruchir Sharma concluded in the Financial Times, “America is now one big bet on AI,” adding, “AI better deliver for the U.S., or its economy and markets will lose the one leg they are now standing on.” This concentration creates fragility, and how the end begins becomes more visible.