Rollovers (Swaps) are applied based on the value date, not the trade date. The value date for most transactions is two business days after the trade date. This means that positions held overnight on Wednesday carry a value date of Friday.
If the position remains open into Thursday, the value date shifts from Friday to Monday (since Saturday and Sunday are non‑business days). As a result, you are charged for three nights of rollover on Wednesday to account for the weekend.
Swap/Rollover values can be found within your trading platform and by clicking here.