Our ARM interest rate changes are tied to changes in an index rate. Using an index to determine future rate adjustments provides you with assurance that rate adjustments will be based on actual market conditions at the time of the adjustment. The current value of most indices is published weekly in the Wall Street Journal. If the index rate moves up so does your mortgage interest rate, and you will probably have to make a higher monthly payment. On the other hand, if the index rate goes down your monthly payment may decrease.