Yes.

Citations:

Apollo Academy: S&P 500 Concentration Approaching 50% - https://www.apolloacademy.com/sp-500-concentration-approachi... - March 14th, 2026

> The 10 biggest companies in the S&P 500 make up almost 40% of the index, and if Anthropic, OpenAI and SpaceX are added later this year, the concentration could approach 50%, see chart below. The bottom line is that the S&P 500 basically doesn’t offer much diversification anymore.

Apollo Academy: Extreme AI Concentration in the S&P 500 - https://www.apolloacademy.com/extreme-ai-concentration-in-th... - January 13th, 2026

> The bottom line is that investors in the S&P 500 remain overexposed to AI.

TLDR Concentration risk https://www.finra.org/investors/insights/concentration-risk

(not investing advice)