The S&P 500 Is Doing Something Not Seen in 60 Years. History Says Investors Should Make This 1 Move Right Now.

The S&P 500 is showing a level of concentration not seen in decades, highlighting a risk for investors even as equities have hit record highs. The index’s top 10 companies account for roughly 40% of its total value, making it the most concentrated since the mid-1960s, according to S&P Dow Jones Indices. The article points to how tech-heavy leadership has powered gains, with Micron Technology returning more than 650% over the past 12 months, alongside major AI-related spending by Amazon and Microsoft. It warns that if tech stocks fall, the broader market could decline as well. Data is as of July 14, 2026, and the Federal Reserve’s potential rate increases later in 2026 could affect AI infrastructure investment. Historically, diversification is framed as the key step, favoring portfolios with at least 50 stocks across sectors held for five years.