Swap: when carrying a position becomes costly

The swap — a fee or credit for carrying a position overnight — is ignored by many until it turns into a noticeable expense. For an intraday trader there's no swap at all, but for those who hold positions for a long time, a negative swap can meaningfully eat into the result. Let's look at when the swap becomes costly.

What the swap is

The swap is credited or charged for holding a position through the moment of rollover (the change of trading day) and is tied to the interest-rate difference of the currencies in the pair. Hold the currency with the higher rate against the one with the lower rate, and the swap can be positive (a credit). In the reverse situation the swap is negative (a charge). The direction and size of the swap depend on the pair, the trade direction, and the broker's terms. The swap applies only to positions held overnight.

When the swap matters and when it doesn't

For an intraday trader who closes trades by evening, the swap plays no role — the positions don't live to rollover. But for a swing and position trader holding trades for days and weeks, the swap becomes significant. A negative swap is charged every night of holding, and on a long position these charges accumulate. What's unnoticeable over one night turns over weeks into a tangible sum that eats into profit or deepens a loss.

How a negative swap accumulates

The main danger of the swap is accumulation. A small overnight charge seems trivial, but multiplied by the number of nights held it grows. A position opened for several weeks with a negative swap can accumulate costs that noticeably affect the trade's outcome. This is especially sensitive on pairs with a large rate difference, where the swap is big. In addition, a triple swap usually occurs on Wednesday (for the coming weekend) — the charge on that day is notably larger than usual.

How to account for the swap

The swap should be checked and built into calculations for long positions. Look at the size and sign of the swap for your pair and direction in the terminal — it differs across brokers and can change the economics of a long trade. For position trading, the swap is part of the holding cost that needs to be subtracted from expected profit. On strategies like the carry trade, the swap is instead a source of income, but there it's offset by the risk of price movement. Account for the triple swap on Wednesdays. Ignoring the swap on long positions leads to an overstated assessment of the result.

The practical takeaway

The swap is a fee or credit for carrying a position overnight, tied to the interest-rate difference of the currencies in the pair. For an intraday trader there's no swap; for a swing and position trader it matters, because a negative swap is charged every night and accumulates: what's unnoticeable over one night becomes a tangible cost over weeks, especially on pairs with a large rate difference and on Wednesday (the triple swap). Check the size and sign of the swap for your pair and direction, and build it into the calculations for long positions as part of the holding cost. Understanding when the swap turns from an unnoticeable trifle into a costly expense helps you correctly assess the economics of long trades and not be surprised why a position that was profitable on the chart brought less than expected.

This material is for educational purposes and is not individual investment advice.