The U.S. stock market has stumbled in 2026. The benchmark S&P 500 (^GSPC 1.33%) has fallen more than 3% even though most companies reported better-than-expected earnings in the fourth quarter. Investors are worried about valuations, especially among artificial intelligence stocks. In fact, the S&P 500 sounded an alarm in February: A popular valuation metric reached...

The U.S. stock market has stumbled in 2026. The benchmark S&P 500 (^GSPC 1.33%) has fallen more than 3% even though most companies reported better-than-expected earnings in the fourth quarter. Investors are worried about valuations, especially among artificial intelligence stocks. In fact, the S&P 500 sounded an alarm in February: A popular valuation metric reached...

The U.S. stock market has stumbled in 2026. The benchmark S&P 500 (^GSPC 1.33%) has fallen more than 3% even though most companies reported better-than-expected earnings in the fourth quarter. Investors are worried about valuations, especially among artificial intelligence stocks. In fact, the S&P 500 sounded an alarm in February: A popular valuation metric reached...