It is crucial to know in advance and to notice for every trade and every currency pair, index, stock etc, the respective cost that a trade will have. One main cost for keeping positions overnight is the swap which is charged from a forex broker, and it can be either positive or negative.
The below data refer to Dukascopy Bank’s Overnight Policy, while needless to mention that every forex broker has its own swaps for the symbols offered for trading. Keep in mind that certain forex brokers offer swap free accounts (Islamic accounts), where no swaps are being charge for keeping overnight positions. The overnight swap prices are determined based on Central Bank rates and any additional costs that may apply from brokers.