AI Stocks Claim Record 45% S&P 500 Market Cap, Invade Bonds and Global Markets

AI-linked companies now command a record 45% of S&P 500 market cap, up 20 percentage points from 25% at ChatGPT's November 2022 launch, per Goldman Sachs. The surge, powered by semiconductors, cloud providers, and AI infrastructure with strong earnings, has spilled into credit: AI debt at 15.4% of U.S. investment-grade bonds ($1.4 trillion total), hyperscalers issuing $121 billion in 2025 bonds versus $28 billion prior average. Taiwan's market cap reached $4.14 trillion, topping the UK, amplifying concentration risks and potential volatility.