What Is a Swap in Forex and CFD Trading?

Definition

The reason the adjustment exists is that every forex or CFD position is really an exposure to two things at once. In a currency pair you are effectively long one currency and short the other, and those two currencies carry different funding rates. On a CFD over an index, share or commodity, you hold exposure funded on margin rather than the asset itself. Rolling that exposure into the next value date has a financing consequence, and the swap is how the broker prices it.

Swap long versus swap short

Brokers publish two separate numbers for each instrument, because the two sides of a trade are not symmetrical. The long rate applies to buy positions and the short rate applies to sell positions, and it is entirely normal for one side to be a cost while the other is a credit — or for both sides to be a cost once the broker’s markup is included.

How rollover works

Spot forex and most CFDs settle on a short delay rather than instantly. If you keep a position open past the point where it would have settled, the broker rolls it forward into the next value date instead of delivering anything. That roll is the moment financing is applied, and it is what people mean by “rollover”.

The practical consequence is simple: a position opened and closed within the same session normally never reaches a rollover, so it is never financed. A position carried across sessions is financed once for every rollover it survives. There is no single industry-wide cutoff time — brokers set their own rollover moment and publish it in their contract specifications, so the only reliable answer for your account is your broker’s own documentation.

Triple swap: when one night counts as three

Markets settle on business days, but calendar days keep running through the weekend. To keep value dates aligned, brokers finance the weekend in advance on a single weekday rollover. On that rollover a position is charged or credited roughly three days of financing at once instead of one. This is usually called triple swap, and it is the single most common reason a trader sees an overnight amount several times larger than expected.

For cost purposes, the useful way to think about it is in financing nights rather than calendar nights. A hold that crosses a triple-swap rollover is financed for more nights than the number of days it spans, and that is exactly how the VeriLots calculator counts it when you model a holding period.

Positive swaps and swap credits

Not every swap is charged. When the funding difference runs in your favour by more than the broker’s markup takes back, the adjustment is paid into your account instead. That is a swap credit, and it is a normal outcome — not an anomaly, and not something that only appears on exotic products.

Why broker swap rates differ

Two brokers quoting the same instrument on the same night can publish very different numbers. Overnight financing is not a regulated, standardised price — it is a commercial term, and almost every input into it is set by the broker.

Because these terms are commercial rather than fixed, they also move. VeriLots keeps a public record of the meaningful ones in the broker repricing log, where spread, commission and swap changes detected across audited broker accounts are listed as they are found.

How swap costs are calculated

There is no single formula that is correct for every broker, because brokers do not all quote the same thing. What is consistent is the shape of the conversion: a published rate has to be interpreted in its own unit, scaled to your position, multiplied by the number of financing events, and then expressed in the currency your account is actually denominated in.

Worked example: a cost and a credit

Assume a hypothetical 1.0-lot position in a US-dollar-quoted pair, held for two nights, on a US-dollar account, where one swap point is worth $1.00 for that position size. Direct costs — spread plus round-turn commission — come to $8.00 in both cases. Only the financing differs.

Change one assumption and the answer changes with it. Hold a third night, cross a triple-swap rollover, switch direction, trade a different account type, or settle into a different account currency, and both totals move. That sensitivity is the reason to model your own case rather than read a rate off a table: run the scenario with your instrument, size, direction and holding period.

Swap and your total trading cost

Swap is one component of four. On its own it tells you very little; what matters is the combined effect of everything that moves your balance between opening and closing a position.

The weighting shifts with holding period. For an intraday trade that never reaches a rollover, spread and commission are the whole story. For a position carried for a week, financing can easily exceed both — or, on the right side of the right instrument, quietly pay for them. This is why a broker with a wider spread can still be the cheaper venue for a swing trade, and why ranking brokers on spread alone is misleading.

What to compare between brokers

A useful swap comparison holds everything else constant. Before concluding that one broker is cheaper to hold with, check that you are comparing the same instrument, the same direction, the same account type and the same quoting unit, and that both figures have been converted into one account currency for a holding period you would actually trade. Then look at whether the terms have been stable, because a favourable rate that was revised last month is not the rate you will pay.

Once those conditions are level, a head-to-head broker comparison is worth reading, and the methodology behind these figures explains what is measured and what is excluded.

Common swap mistakes

How VeriLots handles swap data

Overnight financing is the part of a broker’s cost structure that is easiest to misread, so it gets the most defensive handling in our data-quality checks.

Swap questions, answered