Sun and Moon

Swap (overnight interest)

An amount charged or credited for holding a position past the daily close.

It applies every day, and usually triples on one night of the week to cover the weekend. It can be positive or negative depending on the direction and instrument, though it is negative more often than not. On positions held for weeks it stops being a detail and becomes a real line in the result - which is why a trade's outcome is counted after swap, never before it.

See how the result is counted