Overnight position

A position that survives the daily boundary. The boundary is a stated time on the provider's server clock, conventionally set around the end of the New York session for foreign exchange, and it is the instant at which the value date of a spot position is rolled forward and financing is applied for the night.

Holding through the roll changes the risk as well as the cost. On markets that close, the hours in between contain no dealing at all, so information arriving in them is expressed in the next available price rather than in a series of prices along the way, and no instruction resting in that distance can be filled at the level it names. Requirements can also differ outside main hours, since some firms state higher collateral percentages for positions held over a weekend or into a scheduled release, and those percentages are published per instrument in the contract specification.

The word overnight is the trap: it means the provider's cut off and not local midnight, so a position that feels like an intraday one is charged if it spans that moment, and the same position spans it once on one calendar day and three times on the weekday that carries the triple charge. The mirror error is closing before the cut off and reopening after it, which avoids the financing and pays two more crossings of the spread and two more commissions in exchange. Which of the two costs more is arithmetic specific to the instrument and the size, not a general rule, and it changes whenever either component does.