Many shorted stocks will have a hard to borrow interest fee associated with them.
The hard to borrow interest will begin being charged on a short stock position on the settlement date. When the position is closed, the interest fees will be assessed until the settlement date of the closing transaction. For example, you sell XYZ on Monday, and you close the position on Tuesday. The interest fee would not be charged until Thursday, and your account would only be charged for one day of hard to borrow fees.