At the end of 2021, the S&P 500 (Index: SPX) was just a day shy of its all-time record high of 4,796.56. The total market capitalization of the 505 stocks that make up the index stood at $40.36 trillion ($40,356,495,208,880).

As of the end of 2023, the S&P 500 was approaching that record high again. The index ended 2023 with a market cap of $40.04 trillion ($40,038,562,176,634). The index has retreated a bit from that recent peak in the trading days since but is still hovering near it.

The same is mostly true for the top 10 component stocks that make up the S&P 500 index. At the end of 2021, they accounted for 29.34% of the total valuation of the S&P 500. Two years later, their share increased to 30.86% of the total value of the index. Which is to say the top 10 companies in the S&P 500 relatively grew a little in value while the remaining 495 stocks collectively shrank a little.

The following chart shows the relative shares the top 10 stocks in the S&P 500 index hold within its total market capitalization as of 29 December 2023.

Here is the market cap data for the S&P 500's top ten component stocks:

• Apple (Nasdaq: AAPL) $2,814,709,062,006 (7.03%)
• Microsoft (Nasdaq: MSFT) $2,794,827,802,480 (6.98%)
• Amazon (Nasdaq: AMZN) $1,381,734,349,723 (3.45%)
• Nvidia (Nasdaq: NVDA) $1,223,193,400,000 (3.06%)
• Alphabet (A) (Nasdaq: GOOGL) $826,685,420,000 (2.06%)
• Meta Platforms (A) (Nasdaq: META) $785,652,093,720 (1.96%)
• Alphabet (C) (Nasdaq: GOOG) $701,937,097,500 (1.75%)
• Tesla (Nasdaq: TSLA) $687,211,512,370 (1.72%)
• Berkshire Hathaway (B) (NYSE: BRK-B) $648,922,369,183 (1.62%)
• JP Morgan Chase (NYSE: JPM) $491,760,460,800 (1.23%)

The remaining 495 firms account for 69.14% of the total value of the S&P 500 index.

Since the end of 2023, the S&P 500 hasn't had enough "oomph" to push it to a new record high as the index has pulled back. A good portion of that change is attributable to Apple, which has lost enough value that Microsoft was able to claim the title of being the world's most valuable firm on 11 January 2024.

How long that might last remains to be seen.

References

Standard and Poor. S&P Market Attributes. [Excel Spreadsheet]. 29 December 2023. Accessed 1 January 2024.

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