What overnight financing costs on a position you hold
Spread and commission are charged once, when you open. Swap is charged again every night you stay in. For a position held a week, the cost you paid attention to at entry can end up being the smaller half of the bill.
What swap actually is
Every currency pair is two currencies. Holding a position means holding one and owing the other, and the two carry different interest rates. Swap is the daily settlement of that difference, applied to your position at rollover.
Three consequences follow, and they are the ones that matter in practice.
It has a sign. Swap can be negative, which is the usual case, or positive, in which case holding the position pays you. Which side is which depends on the rate differential and on the broker's own markup.
Long and short are not mirror images. You might expect one to earn exactly what the other pays. Brokers apply a markup to both directions, so the pair is usually asymmetric and both sides can be negative at once. The calculator shows the long and short figures separately for this reason.
One night a week counts as three. Markets settle two business days forward, so one weekday carries the weekend. On that day, most brokers apply three days of swap in a single charge. Which day it falls on differs by instrument class, so read your broker's contract specification rather than assuming.
Why the same trade costs two different amounts
Consider the same position, same size, same instrument, held for different lengths.
| Held | Swap charged | What dominates the cost |
|---|---|---|
| Minutes | None | Entry cost |
| One day | One night | Entry cost |
| One week | Seven nights, one tripled | Usually swap |
| One month | Around thirty nights | Swap, by a wide margin |
The entry cost is fixed no matter how long you hold. The swap is not. This is why an account that looks expensive to a scalper can be the cheaper account for someone holding positions, and the reverse.
Where rebate fits
Rebate is paid per lot traded, so it scales with how much you trade, not how long you hold. That makes it a direct offset against spread and commission, and no offset at all against swap.
So the honest summary is: rebate reduces your entry cost, and does nothing about your holding cost. Anyone telling you rebate makes overnight positions cheaper is describing something else.
Check it before you hold, not after
The [cost calculator](/tools/calculator) shows the long and short swap for the instrument and account type you pick, alongside the spread and commission, so you can see all three components before the position exists rather than reading them off a statement afterwards.
For a position you intend to hold, do the arithmetic once: nights you expect to hold, times the nightly figure, plus one extra charge if a triple day falls inside the window. If that number changes your mind about the trade, it was worth the minute.
Swap rates are set by the broker and change. Check the current figure for your instrument rather than relying on one you looked up previously.
Next
- [What a lot really costs, in three components](/bai-viet/real-cost-of-one-lot)
- [Advertised spread and the spread you actually get](/bai-viet/advertised-vs-actual-spread)