When is rollover booked?
5 p.m. in New York is considered the beginning and end of the forex trading day. Any positions that are open at 5 p.m. sharp are considered to be held overnight, and are subject to rollover. A position opened at 5:01 p.m. is not subject to rollover until the next day, while a position opened at 4:59 p.m. is subject to rollover at 5 p.m.
A credit or debit for each position open at 5 p.m. appears on your account within an hour, and is applied directly to your accounts balance.
Weekends and Holidays
Most liquidity providers (which include global banks, financial institutions, prime brokers and other market makers) across the globe are closed on Saturdays and Sundays, so there is no rollover on these days, but most liquidity providers still apply interest for those two days. To account for that, the forex market books three days of rollover on Wednesdays, which makes a typical Wednesday rollover three times the amount on Tuesday. There is no rollover on holidays, but an extra days worth of rollover two business days before the holiday. Typically, holiday rollover happens if any of the currencies traded has a major holiday. Therefore, Independence Day in the USA, July 4, closes American liquidity providers, and an extra day of rollover is added at 5 p.m. on July 1 for all U.S. dollar pairs.