Top 15 S&P 500 stocks account for record 46.7% of index value, surpassing 2000 Dot-Com Bubble level

The top 15 stocks in the S&P 500 now represent 46.7% of the index's total market value, a record high that exceeds the 27.2% held by the same group during the 2000 Dot-Com Bubble by 19.5 percentage points. Nvidia leads with 7.5% weight, followed by Apple at 7.1% and Alphabet at 5.9%. Together, these three mega-cap firms hold 20.5% of the index, while the 434 smallest companies collectively match the market value of the five largest stocks, highlighting an unprecedented concentration of wealth.