The S&P 500 Price Return Index is a stock market index that tracks the performance of the 500 largest publicly traded companies in the United States. It is a market-capitalization-weighted index, meaning that the companies with the highest market capitalization have the greatest influence on the index's performance. The index is calculated using the price return method, which means that it only takes into account the price changes of the stocks in the index, and does not include dividends.