Have you ever wondered why holding overnight orders requires extra fees, even when the asset price may not move at all? That is swap, a fee that many beginner traders often overlook until they face the real deal.

What exactly is a swap? Simply put, it is the interest for holding a position overnight. When you open a trade order and leave it beyond market closing time, the market will charge this fee. And importantly, it’s not just a random fee set by brokers; it has a real basis.

When you trade currency pairs, such as EUR/USD, you are "borrowing" one currency to "buy" another. Each currency has its own interest rate set by its central bank, such as the FED for the dollar or the ECB for the euro. Therefore, a swap is the net difference in interest between the two sides.

Imagine the euro has an interest rate of 4.0% per year, but the dollar offers 5.0% per year. If you buy EUR/USD (buy euro, borrow dollars), you earn euro interest but pay dollar interest. The difference of -1.0% per year means your swap will be negative—you have to pay. Conversely, if you sell EUR/USD, the difference becomes positive.

In reality, brokers act as intermediaries for this borrowing. They add their own management fees on top. So, even if theoretically you should receive a positive swap, the broker might deduct some or turn it negative on both sides. This is why Swap Long and Swap Short are not exactly equal.

There are two main ways to calculate swaps. If the broker shows it in points, you need to multiply by the value of 1 point. If it’s shown as a percentage per night, it’s easier—multiply the total position value by that percentage.

For example, you buy 1 lot of EUR/USD at 1.0900. The long swap is -0.008% per night. The total position value is $109,000. Calculate 109,000 multiplied by -0.008% to get -$8.72 per night. And this is what many people miss: if that night is a Wednesday night, you will be charged a 3-day swap, totaling -$26.16, even when the price hardly moves.

A 3x swap is a common pitfall for beginner traders because the Forex market closes on weekends, but interest in the financial world continues every day. Brokers must aggregate the swap fees for Saturday and Sunday into the trading day, usually on Wednesday, due to the T+2 settlement cycle.

The risk of swaps is clear, especially for traders holding positions for a long time. Swap is calculated based on the full value of the position, not just the margin you put up. If you use high leverage, swaps can eat up your margin and wipe out your account, even if the market moves against you.

But swaps are not just about risk; they also create opportunities for certain strategies. Carry Trade is a strategy of "borrowing" low-interest currencies to "buy" high-interest currencies to earn daily swap income. For example, buying AUD/JPY to profit from the interest rate differential. The risk is that if the exchange rate moves against you, the loss could be greater than the accumulated swap profit over years.

For those who want to avoid swaps, there is an option: Swap-Free or Islamic accounts, which do not charge swap fees regardless of how long you hold the order. These are suitable for Muslim traders and Swing Traders who want to hold positions for weeks or months.

In summary, swaps are a cost that must be well understood, depending on your trading style. For scalpers closing trades within minutes, it has little impact. But for swing traders or position traders holding for months, it’s a crucial factor. Choosing a transparent broker that clearly displays swap information will help you plan your trades carefully and avoid hidden costs surprising you later.