Abstract: A computer implemented method of assessing an interest increase in an annuity linked to an index of equities includes determining a change in an equity index over a time period, setting an interest increase in an annuity to a floor if the determined change in the equity index is not greater than the floor, calculating the interest increase in the annuity to be a participation percentage of the determined change in the equity index if the determined change is greater than the floor where the participation percentage of the determined change is calculated up to a threshold change level in the determined change in the equity index, and adding an enhanced interest increase amount to the interest increase in the annuity if the determined change in the equity index is greater than the threshold change level. The enhanced interest increase amount is an enhanced percentage of the determined change in the equity index above the threshold change level.