Data from independent research firm The Kobeissi Letter shows that the 15 largest stocks by market capitalization in the S&P 500 now account for a record 46.7% of the index's total market capitalization. In contrast, during the dot-com bubble of 2000, the 15 largest stocks accounted for only 27.2% of the index's total market capitalization. Nvidia, Apple, Alphabet, and Microsoft account for 7.5%, 7.1%, 5.9%, and 5.6% of the index's total market capitalization, respectively, totaling 26.1%. The market capitalization of these four stocks alone exceeds the combined share of the next 11 stocks. Furthermore, the combined market capitalization of the five largest stocks in the index is now equivalent to the combined market capitalization of the 434 smallest stocks, a record gap.
