Swap rates and overnight financing, explained

A retail FX position looks simple: you buy one currency and sell another. Underneath, it carries a cost that many traders only notice when they hold trades for days or weeks. That cost is the swap, also called rollover or overnight financing, and it can turn a small profitable position into a losing one over time.

What a swap is

When you buy EUR/USD, you are economically long euros and short dollars. If the position were settled like a real currency exchange, you would be holding euros and owing dollars, earning interest on one and paying it on the other.

Spot FX is defined by settlement: the Bank for International Settlements describes a spot transaction as an exchange of two currencies for delivery within two business days. Retail traders do not want delivery, so brokers roll open positions forward each trading day at the cut-off, which by market convention is 5pm New York time. The rollover carries a price that reflects the difference in interest rates between the two currencies for the extra day.

How the rate is built

A swap has two parts.

The interest differential. If the currency you are long pays a higher interest rate than the one you are short, the differential works in your favour. If it pays less, it works against you. The underlying rates are usually drawn from short-term market rates for each currency, as reflected in the cost of rolling positions in the institutional market.

The broker’s markup. Brokers add a charge on top, in both directions. That is why a trader can pay financing on both a long and a short position in the same pair: the markup can be large enough to turn a small positive differential into a charge.

The markup is where practices differ most. In its November 2025 review of CFD providers, the UK Financial Conduct Authority reported wide variation in the effective interest rates retail clients paid on overnight funding, without adequate justification from the firms. It also found cases where firms charged clients on short positions while other providers would have paid a credit on the same position, and firms applying funding charges to matched long and short positions that offset each other.

Swaps rarely matter on a trade closed the same day. Over weeks, they can decide whether a position makes or loses money.

Why Wednesday often costs three times as much

Most FX pairs settle two business days after the trade date. A position rolled at Wednesday’s cut-off moves its value date from Friday to the following Monday, because Saturday and Sunday are not settlement days. That single roll covers three calendar days of financing, so brokers apply three days’ swap to positions held through Wednesday’s close.

The result is the triple-swap day. A few points are worth knowing:

• Pairs with a different settlement convention can have their triple day on another weekday.
• Public holidays in either currency’s home market can add extra days to a roll.
• CFDs on indices, commodities and shares often charge the weekend on Friday instead, because their financing is not tied to FX settlement dates.

Your broker’s swap schedule, usually published per instrument, is the authority. It will state the long and short rates, how they are expressed (points, percentage or account currency) and which day carries the triple charge.

Swap-free and Islamic accounts

Many brokers offer swap-free accounts, often marketed as Islamic accounts for clients who cannot pay or receive interest for religious reasons. They remove the interest-based swap. They do not usually remove the cost of holding a position.

Common structures include:

• A fixed administration or holding fee per lot per night, sometimes starting only after a grace period of several days.
• Wider spreads or higher commissions on the account.
• Restrictions on which instruments can be held swap-free, or for how long.

None of this is improper if it is disclosed. The practical point is to compare the total cost of holding a position over your typical holding period, on both account types, rather than assuming swap-free means free.

What to check before holding overnight

• The long and short swap rates for the pair you trade, not only the spread.
• How the rate is expressed, and how it converts into your account currency.
• Which day carries the triple charge for that instrument.
• Whether the broker publishes the benchmark rates and markup it uses.
• For swap-free accounts, the administration fees and when they start.

In the US, the National Futures Association expects retail forex dealers to design their platforms so that automatic rollovers follow the terms disclosed in the customer agreement, and to confirm rollovers to customers. Wherever you trade, the customer agreement and swap schedule are the documents that tell you what you will actually pay.