In forex, the rollover rate is the net interest return on a trader's overnight currency position. To put it another way, when trading currencies, an investor borrows one currency to buy another. The interest paid or collected for keeping the investment overnight is referred to as the rollover rate. After 5 p.m. EST, any open currency position will be held overnight.

The rollover rate converts a percentage of net currency interest rates into a cash return on investment. The rollover interest charge is calculated using the difference between the two interest rates of the exchanged currencies. The investor benefits if the rollover rate is positive. The investor will be charged a fee if the rollover rate is negative.