The back-of-the-envelope math is harsh: AI capex coming from tech companies listed in the S&P 500 is $400 billion or more per year, going forward. The biggest AI company—OpenAI, the maker of ChatGPT—has disclosed revenues of just$13 billion for 2025. Altman recently said revenues were “well more” than that , hinting they may hit $100 billion in 2027. But that’s still nowhere near the level of capex it’s committing to.On one level, that’s normal: Most industries feature a collection of companies that do bus ...