What You Should Do About the Stock Market’s Giant Problem - WSJ

1. Top 10 S&P 500 companies comprise 37.5% of market value, indicating concentration. 2. Overvaluation risks loom as S&P 500 trades at 22 times expected earnings. 3. Magnificent Seven's dominance drives market returns, particularly Nvidia's massive gains. 4. Historical market concentration levels show large firms have traditionally dominated. 5. Young investors benefit from human capital, mitigating risks of overvalued stocks.