In the last 10 years, the composition of the largest 25 companies by market cap in the S&P 500 has changed dramatically. Only 40% of the companies that were in the top 25 in 2011 remain there today. Additionally, the sector breakdown has shifted considerably. Sectors like Technology, Communication Services, and Consumer Discretionary have seen increases in their representation in the top 25 while the Energy, Consumer Staples, and Industrial sectors have seen declines.

Of the companies listed on both the 2011 and 2021 lists, the median total return excluding dividends over the last 10 years has been 312.33%, while the mean total return excluding dividends has been 606.65%. Apple (AAPL), Microsoft (MSFT), Alphabet (GOOGL), and Amazon (AMZN) have seen the largest appreciation of this group and are currently the four largest companies in the index.

As noted above, just 40% (10) of the companies on the list in 2011 made the cut in 2021, and as shown in the table below, while Apple (AAPL) and Microsoft (MSFT) remain in the top four, Exxon Mobil (XOM) and IBM not only fell out of the top four but also the top 25 altogether. Which top companies on the list now won’t be there in 2031? We wish we had a crystal ball!

Whereas the market cap of the S&P 500 has increased by 270% since 2011, the total value of the four largest companies has increased by 673%. In terms of market cap, the four largest companies account for just over 20% of the entire S&P 500’s market cap, and the 25 largest companies make up 49% of the total. In 2011, by contrast, the four largest companies had a weighting of 10%, and the 25 largest accounted for about 36% of the total market cap.  

(Click on image to enlarge)