[AI Stocks Account for 45% of S&P 500 Market Cap, Debt Reaches $1.4 Trillion] According to The Kobeissi Letter, AI-related stocks account for 45% of the total market capitalization of the S&P 500 Index, rising by 20 percentage points since the release of ChatGPT in November 2022, marking a record high. The proportion of AI-related investment-grade debt has risen to 15.4%, making it the largest sector in the U.S. credit market. This represents a 3.5 percentage point increase compared to 2020, with the corresponding debt volume doubling to a historic peak of $1.4 trillion.