AI Stocks Are Creating a Sneaky Risk for S&P 500 Investors, and History Is Flashing a Warning Signal

Key Points The S&P 500's top holdings account for close to 40% of the index's value. Historically, it's rare for the broader market to be so heavily concentrated in relatively few stocks. Even if a downturn is coming, there's still good news for investors. 10 stocks we like better than S&P 500 Index › The S&P 500 (SNPINDEX: ^GSPC) has been working overtime the last few years, earning total returns of nearly 18% over the last 12 months alone -- far above its historic average of around 10%. Advancements in artificial intelligence (AI) can be credited for much of the market's recent success.