Direct answer: what “rollover” means
In forex, rollover is the mechanism used to account for the interest effect of holding a position from one dealing day to the next. In practice, a platform typically credits or debits a payment so the position carries the interest differential implied by the two currencies and by the provider’s specific swap pricing rules.
For AUD USD and NZD USD, the key idea is the same: rollover is driven by interest-rate inputs for the AUD vs USD leg (for AUD USD) or the NZD vs USD leg (for NZD USD), then transformed into a signed cash adjustment using your position direction (long vs short) and the platform’s conventions.
Mechanism: the common inputs behind rollover
1) Interest-rate differential (stable concept)
At a conceptual level, rollover moves in the direction of the interest-rate differential between the two currencies in the pair. A higher interest rate in the “base” currency relative to the “quote” currency usually implies one sign for holding a position, and reversing the rates implies the opposite sign.
A simple way to state the logic is:
- If you are long a currency with the higher interest rate versus a lower-rate counter-currency, rollover tends to behave differently than if you are short that higher-rate currency.
- The exact sign depends on how the pair is defined and how the provider converts the differential into a posted adjustment.
Because the actual interest rates and market-specific short-term rates can change, you must treat any numeric example as illustrative unless you use current inputs from the relevant reference (for example, central bank rates, money-market benchmarks, or the provider’s own disclosed rate assumptions).
2) Position direction (stable concept)
Rollover is generally applied with sign:
- Long vs short: holding one direction typically results in a credit, while the opposite direction typically results in a debit, all else equal.
- Whether it’s “positive rollover” or “negative rollover” for your trade depends on your side and the provider’s mapping from the interest differential to their swap charge.
3) The provider’s swap pricing convention (variable in detail)
Even if two providers use the same underlying interest-rate concept, the posted rollover can differ because providers may:
- Add an internal markup or adjustment to cover operational and pricing costs.
- Use a specific day-count convention and conversion approach.
- Apply rounding and minimum increments.
So, to compare AUD USD vs NZD USD rollover, you compare like with like: the same platform’s posted rollover schedule and convention, using the same position size and time conditions.
4) Triple-swap style conventions (why AUD USD and NZD USD can differ in practice)
Some platforms apply an additional convention around rollover timing (commonly around the weekend) that can be described as a “triple swap” effect: instead of charging or crediting for one dealing day, the accounting may cover multiple calendar days’ worth of interest.
In a simplified interpretation, triple-swap can appear when:
- The system rolls through a period where the normal “one day” interest accrual is insufficient to represent the time gap.
- The provider applies extra days’ worth of swap based on their schedule.
Important limitation: “triple swap” is a convention describing how many days are included in the provider’s rollover posting. It does not automatically mean a literal interest-rate computation is exactly three times a day’s value in every model; providers may incorporate their own adjustments.
Evidence or example (with explicit assumptions)
Because no real-time rates are assumed here, use a verification-style example with placeholders.
Assumptions for the example:
- You hold a position through the provider’s normal rollover point for one dealing-day accrual.
- The provider posts a swap based on an underlying interest differential converted into your account currency.
- Swap rates are quoted per unit (or per lot) and then multiplied by your position size.
Illustrative calculation structure:
- Start with an interest-rate-based swap component for the pair’s two-currency relationship. 2) Convert it into a cash amount per unit, using the provider’s lot size and any required currency conversions. 3) Apply direction:
- Long position: add or subtract based on the provider’s sign convention. - Short position: the sign flips in the posted adjustment.