US 500 (S&P 500) Explained: Composition, Weighting, and Historical Performance

The US 500 (also known as SPX500, US SPX 500 or SP500) - more commonly known as the S&P 500, or the Standard and Poor's 500 - tracks the performance of the 500 largest companies listed on the NYSE, Nasdaq and BZX exchanges. In short, the index tracks the performance of the biggest US companies. The index is, perhaps, the most important and most followed in the world, given that it includes around 80% of the total market cap of publicly listed US companies.

Weighting and Composition

The index is a market capitalisation weighted index, meaning that the larger a company's market cap, the greater the weight that it has in the index. As of the start of 2024, the 10 largest stocks in the index comprise around a third of the index's total weight. Components of the US 500 are not selected by any strict rules-based system, and instead are decided by a committee at S&P Dow Jones Indices. Typically, however, new additions to the index are considered based on their market cap, trading volume, the exchange upon which they are listed, and the country in which the stock in question has its primary listing. The index is typically rebalanced on a quarterly basis, after market close on the third Friday in March, June, September, and December each year.

Historical Performance

Historically, the US 500 has tended to perform well on an annual basis, as the below shows. Of course, past performance is no guarantee of future results.

Gaining Exposure to the S&P 500

The S&P 500 is a stock market index, not a directly investable asset. However, you can still participate in its performance through various investment options. These include:

• Mutual funds and ETFs: These track the S&P 500, offering a diversified way to invest in the U.S. stock market.
• CFDs (contracts for difference): These are financial instruments used for trading, allowing speculation on the price movements of the S&P 500.

Important Note: CFDs are complex instruments and carry a high risk of losing money quickly due to leverage. Make sure you understand how CFDs work and can afford to take the high risk involved before trading them.