The S&P 500 is widely regarded as the best single gauge of large-cap U.S. equities. The 500™ measures the performance of 500 companies that represent more than 80% of the investable U.S. equity market. At the end of 2024, more than USD 20 trillion around the world was indexed or benchmarked to the large-cap U.S. equity barometer.
In this paper, we will:
- Outline the global significance of large-cap U.S. equities;
- Demonstrate the S&P 500’s distinct characteristics compared to the Japanese equity market;
- Show how incorporating large-cap U.S. equities could have helped Japanese investors to improve performance, historically; and
- Highlight the historical benefits of taking an indexed-based approach to large-cap U.S. equities.
Significance of the S&P 500 in the Global Equity Market
The S&P 500 represents a significant part of global equity market capitalization, with index members representing 54.5% of the float-adjusted market cap of the S&P Global BMI as of Sept. 30, 2025. This was more than nine times larger than Japan’s weight in the global equity opportunity set. The scale of the large-cap U.S. equity segment also means that, among the 100 largest stocks in the S&P Global BMI, 75 were S&P 500 members.
