The top 10 stocks of the S&P 500 have typically made up a sizable portion of the index’s total market cap. Between 1880 and 2010, the top 10 stocks comprised an average of about one-quarter (24%) of the index from 1880 to 2010.

Recently, that number has shot up. Between 2010 to 2024, their share of the S&P 500’s market cap doubled from 19% to 38%.

A highly concentrated index can introduce new risks of increased volatility and higher potential losses for investors if its major companies face downturns. Source 🔗