Under normal circumstances, at least 80% of the fund's total assets will be invested in component securities of the index and investments that have economic characteristics that are substantially identical to the economic characteristics of such component securities. The index tracks the value of a cash-secured put option sales strategy, which consists of selling (or "writing") S&P 500 Index put options ("SPX Puts") and investing the sale proceeds in one- and three-month Treasury bills. The fund is non-diversified.