Overnight swap: the cost that quietly decides whether a swing trade is worth holding

Swap is quoted in points, charged every night, and tripled on Wednesdays. Over a two-week hold it can absorb a fifth of your target profit. Most traders check it after the position closes, when the number is already booked. This article puts the calculation where it belongs — before entry.

What the swap actually is

Holding a position through the daily rollover is, in substance, borrowing one currency to hold a deposit in another. The interest differential between the two is passed to your account as a charge or a credit, and the broker applies a markup on top of it. That markup is why the number on your statement rarely matches the policy-rate difference you can look up on a central bank website.

The arithmetic is short enough to do in your head once you know where to look:

swap per night (account currency) = swap in points × point value × lots

For a standard lot of a pair quoted to four decimals, the point value is 10 units of the quote currency. For a mini lot it is 1. The swap in points is published by the broker and changes daily, so the figure you calculate today is an estimate of tomorrow's charge, not a contract.

Where the number is actually published

There are three places to read it, and they disagree often enough that it is worth knowing all three. The contract specification in the platform — right-click the symbol, choose specification — lists swap long and swap short in points. The broker's website publishes the same table, usually with the rollover time stated next to it. And your own statement shows what was actually charged after the first night, which is the only figure that settles the question.

What you should not do is infer the swap from the headline policy rates. On major pairs the differential is frequently smaller than the broker's markup, which means the sign of the carry can be the opposite of what the rate table suggests. On minor and exotic pairs the differential dominates, and the markup is the smaller error.

A worked example

Take a long position of one standard lot in EUR/USD, with the contract specification showing swap long at −0.85 points per night.

Per night, the charge is 0.85 × 10 = 8.50 US dollars. On its own that looks negligible against a 100,000-unit position. The mistake is measuring it per night instead of per hold.

Suppose the trade is held for fourteen calendar nights and two of those nights are Wednesdays. Wednesday is charged at triple rate because it carries the weekend, so the chargeable nights are 14 + 2 × 2 = 18 nights. Total financing: 18 × 8.50 = 153 dollars.

Now compare that with the trade itself. An 80-pip target on one lot is 800 dollars, so financing takes 19 per cent of the gross result. A 40-pip stop is 400 dollars, so the same 153 dollars deepens the loss by 38 per cent. And the position needs 15.3 pips of favourable movement simply to get back to flat — before spread, before commission.

None of this makes the trade wrong. It makes the trade a different trade from the one the chart suggested.

Wednesday is not a detail

The triple charge is the single most mispriced item in swing trading, because it is invisible on a one-night test and material on a two-week hold. Two Wednesdays inside a fourteen-night hold added four extra nights in the example above — 29 per cent more financing than a naive count would suggest.

Holiday rolls compound the same logic. Around year-end and around US Thanksgiving, several brokers extend the roll to three or four nights. If a position is opened specifically to capture a multi-day move across a holiday, the financing should be part of the plan rather than a surprise on the statement.

The rollover timestamp matters too. Most brokers roll at 00:00 server time, which for many server settings falls inside the New York afternoon. A position closed twenty minutes before the roll avoids the charge; whether that is worth doing depends on the round-trip cost of closing and reopening, which is usually larger than one night of swap on a major pair and smaller than one night on an exotic.

The break-even holding period

Turn the calculation around and it becomes a filter rather than a cost report. Divide your expected edge by the nightly charge and you get the number of nights the position can run before financing consumes the entire thesis:

break-even nights = expected edge in points ÷ swap in points per night

With a 20-pip edge and 0.85 points of nightly carry, the answer is roughly 23 nights. Beyond that point the position is no longer trading your view; it is financing the broker. For a swing trade planned over three to five weeks, that is a real constraint and it belongs in the position sizing, not in the post-mortem.

When paying carry is the right decision

Negative carry is not automatically a reason to avoid a trade. It is a reason to demand a larger edge.

There are three situations where accepting the charge is clearly correct. The first is a hedge: the financing is the cost of the insurance, and it should be compared with the drawdown it prevents rather than with the profit target. The second is a thesis that only resolves over weeks — a policy divergence, a repricing cycle — where the expected move is an order of magnitude larger than the carry. The third is when the carry runs in your favour: on the short side of the same pair the sign may flip, and a position that pays to be held changes the entire risk profile of the plan.

What is not correct is treating the swap as noise because it is small per night. Per night it always is.

Four conditions before you hold overnight

Write these down before entry, and the decision stops being a judgement call after the fact.

First, is the planned holding period longer than five nights? If not, the swap is a rounding error and can be ignored. If it is, price it.

Second, does the estimated financing exceed 20 per cent of the target? If it does, the structure is wrong, not the direction — widen the target, shorten the hold, or reduce size so the ratio falls back into range.

Third, does the carry direction agree with your bias? Paying carry to hold a view is acceptable; paying carry without noticing is not. The same analysis on the opposite side of the book may show a credit rather than a charge.

Fourth, does the rollover window sit near your stop? Spreads widen around the roll and stops placed inside that window are filled at worse prices than the chart implies. Move the stop or accept the extra slippage deliberately.

Run the four checks once, at the planning stage, and the swap line on the statement becomes a confirmation rather than a discovery.

Risk notice

This article is for education and information only and does not constitute investment advice. Swap rates, markups and rollover schedules differ by broker and change without notice; the figures used here are illustrative and should be replaced with your own contract specification before any decision. Trading on margin carries a high level of risk and you may lose more than your initial deposit.