The S&P 500, or Standard and Poor’s 500, is a widely recognized stock market index that tracks the performance of 500 of the largest publicly traded companies in the United States. Representing a broad spectrum of industries, it covers around 80% of the total market capitalization of U.S. public companies, making it a key indicator of overall market health. As of early 2024, the S&P 500’s aggregate market cap exceeds $43 trillion. This index is capitalization-weighted, meaning that larger companies have a greater impact on its performance. Major constituents include industry giants like Apple, Microsoft, Amazon, and Alphabet. While the index comprises 500 companies, it actually has 503 components because three companies have two share classes listed. The index is rebalanced periodically to ensure it remains representative of the U.S. equity market. It plays a crucial role in economic forecasting and is often referenced by its ticker symbols ^GSPC, INX, and $SPX.