The Rydex Series Fds, Inverse S&P 500 Strategy Fund Investor Class (RYURX) is a mutual fund that aims to provide investors with inverse exposure to the S&P 500 index. This means that the fund will seek to generate returns that are opposite to the performance of the S&P 500 index. This fund is designed for investors who are looking to hedge against potential market downturns or to take advantage of market volatility. The fund is managed by Rydex Investments and is available to individual investors through the Investor Class shares.