Direct answer
Rollover for GBP/CHF is the net “carry” added to or removed from an FX position when it’s held overnight. In the simplest explanation, it comes from the interest-rate difference between the two currencies (GBP versus CHF), then gets modified by the provider’s swap pricing conventions and by special rollover rules such as “triple-swap” at certain times.
Mechanics: what goes into a rollover number
Start with a definition. In FX markets, two currencies are exchanged at an agreed spot rate and the position is later “rolled” by entering the offsetting leg. The overnight cost or credit for holding that exposure is often described as swap, rollover, or carry.
A plain, checkable way to think about the inputs is this:
- Interest-rate inputs (market drivers). The relative interest environment of GBP and CHF influences the direction and rough size of carry. When the GBP interest rate is higher than CHF, the simplified net carry tends to be more favorable to holding GBP versus CHF; if it’s lower, the net carry can be unfavorable.
- Direction matters. For a GBP/CHF position, being long GBP/CHF means you are effectively long GBP and short CHF. Being short GBP/CHF flips the carry sign.
- Provider adjustments. Even if two providers use the same underlying rate environment, the displayed rollover can differ because providers convert the underlying carry into a client-facing “swap” using their own pricing conventions. Those conventions can incorporate how they handle funding, internal markups, and the way they map raw rates to a tradable contract.
- Day- and time-based conventions. Many platforms apply additional handling when the rollover would span a non-trading period (commonly associated with weekend treatment). This is frequently described as a triple-swap on specific rollover cycles. Practically, this means the overnight rollover shown for that period can be larger in magnitude than on a normal day.
A material assumption for any example
Because providers may compute and publish rollover differently, any numeric example must state assumptions. For instance, if you use an interest-rate difference model, you must assume:
- the rollover is based on an annualized rate environment converted to an overnight period,
- the conversion to the quoted pair size uses a standard contract multiplier, and
- the provider’s displayed swap does not include extra fees beyond what your model accounts for.
If any of those assumptions are wrong for your exact account or platform, the calculated number will not match the provider’s credited or charged rollover.
Evidence or example (illustrative, not a guaranteed match)
Here is an illustrative structure you can use to independently reason about GBP/CHF rollover without relying on live quotes.
- Choose the direction. Assume you hold GBP/CHF overnight.
- Compute the interest-rate difference conceptually. Compare the relative interest environment of GBP and CHF (higher-rate currency tends to be the “credit” side in a long position, lower-rate currency the “debit” side).
- Convert to an overnight fraction. Convert annualized interest into an overnight period using a day-count convention (for education, the exact convention matters and is often not identical across systems).
- Apply sign and magnitude conventions. The sign flips for long versus short. Then apply any triple-swap multiplier if the rollover cycle spans a longer non-trading interval.
Why your computed result may differ from the displayed rollover
A common failure mode is to stop at step 3 and assume the provider’s displayed swap equals your simplified interest-difference conversion. In practice, provider conversions can differ due to internal pricing, fee components, and the mapping from underlying carry to the client’s contract specification. Another failure mode is ignoring triple-swap or using the wrong rollover time relative to the platform’s settlement window.
Limitations and risks (what can go wrong when you try to “calculate” it)
- **Provider-specific swap conventions are the biggest variable. ** Even with the same underlying interest environment, the client-facing rollover may not match a generic formula because the provider publishes (and bills) rollover according to its own convention. - **Triple-swap can dominate. ** On rollover cycles that require additional days of carry, the magnitude can change sharply. If you compare two consecutive days without accounting for this, the pattern may look inconsistent. - **Costs and execution details affect the realized outcome.