S&P 500 Stock Index Forecast. Below is a forecast of the Standard and Poor's 500, or S&P 500, broken down by month. This forecast is produced based on prior values of the S&P 500 along with other factors such as other stock market indexes, interest rates, currency exchange rates, and economic indicators. S&P 500 (SPX) Index Forecast, News & Analysis, Page S&P 500 Weekly Price Forecast – Stock Markets Give Up Gains for the Week. US Stock Market Overview – Stocks Drop and Finish the Worst Quarter Since 2008. Housing prices remain buoyed .