• Seven companies accounted for roughly one-third of the S&P 500 at Tuesday’s close, with a combined value of about $23 trillion.
• The index’s 10 largest companies reached almost 40% of its value in mid-2025, versus under 20% in 2015.
• That concentration exceeded the dot-com peak in 2000, when the 10 largest companies represented over 25% of the index.
• Apple, Nvidia and Microsoft alone were valued at $13.1 trillion, highlighting index investors’ exposure to a small group of technology companies.
• Holdings across index funds, technology funds and 401(k) accounts can overlap, increasing portfolio exposure to the same seven companies.

Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Insight Guru Inc. published the original content used to generate this news brief on November 11, 2026, and is solely responsible for the information contained therein.