Tech Titans Dominate S&P 500

The S&P 500 index is dominated by just two companies: Apple and Nvidia. Together, they account for more than 15% of the index's value, a record level that surpasses even the dot-com era. In comparison, Microsoft and General Electric represented around 9.1% of the index before the bust.

The success of these tech giants has led to an unusual phenomenon: market-cap weighting is increasingly being determined by just two stocks. Apple's recent all-time high of $345 after unveiling its new iPhone 18 and foldable phone, as well as Nvidia's 21% year-to-date gain on Jensen Huang's prediction that the chipmaker could grow faster without supply constraints, have significantly contributed to this trend.

This concentration creates tension within the S&P 500, which is designed to capture the performance of hundreds of large American companies. The index now has its top 10 largest companies accounting for roughly 40% of the total, up from around 17% a decade ago.