The returns that you get from an indexed CD are not fixed over time. The interest payable is linked to something--be it a stock market index such as the S&P500, the prime rate, the yield on T-bills, a clutch of foreign currencies or even the cost of college tuition. Maturities on these CDs can be as short as 6 months or as long as 25 years, with minimums required as low as $250. There’s usually a cap from the gains that you get when the underlying index rises and if it falls, you get little or no interest but at least your principle is protected. It’s other attractive feature? Deposits are insured by the FDIC up to $250,000.