What rollover means in CHF crosses
Rollover (also called a swap) is the cost or credit applied to an open forex position when it is held past the market’s daily settlement cut-off. In a CHF cross, the “rollover” is not an extra fee on top of the FX move itself; it is an overnight interest carry component implied by the two currencies used in the pair.
A useful way to think about it:
- If you hold a position long one currency and short the other, the overnight value tends to follow the interest-rate relationship between those currencies.
- If the overnight interest differential favors the currency you are effectively long, the rollover is more likely to be a credit; if it favors the currency you are effectively short, it is more likely to be a debit.
This general mechanic does not guarantee a particular outcome on any specific trade, because the amount you see can be adjusted by provider conventions and by how your contract is defined.
The basic mechanics: interest inputs and the pair relationship
1) Start from an overnight interest differential
For a CHF cross (for example, CHF vs another currency), the rollover concept starts with an interest-rate input for each currency. Conceptually, you combine them into a single differential that reflects the cost of funding the currency you are short versus the benefit of receiving interest on the currency you are long.
You can model the sign like this (conceptually, not as a universal formula):
- Long CHF position: you are effectively long CHF and short the other currency.
- Long other-currency position: you are effectively long the other currency and short CHF.
The rollover you pay or receive should track which side has the higher implied overnight rate.
2) Convert the differential into a monetary swap amount
Even if two CHF-side interest rates differ, what you care about is the swap posted to your account in currency terms. Providers typically convert the interest differential into a per-contract or per-notional amount using contract size conventions, day-count conventions, and pricing conventions.
Because contracts differ, you should treat any worked example as an illustration that depends on assumptions such as:
- position size (notional/contract units)
- whether swap is quoted per unit or per lot
- which day-count and reference rates are used
3) Apply provider adjustments (where “calculation” often differs)
A key limitation is that the interest differential is only the starting point. The final swap you see can include adjustments such as:
- provider markup or spread on swap rates
- conversion into account currency
- rounding rules and timing rules tied to execution and the provider’s server time
So two accounts, even with the same market interest environment, can show different rollover amounts because the “provider adjustment” layer is contract-specific.
Why CHF cross rollovers can involve a “triple swap”
On many platforms, rollover is applied daily, but special cut-off periods can increase the effective number of days rolled over. Around certain days where markets are closed or settlement conventions extend, providers may apply a “triple swap” amount so that one posting covers multiple calendar days.
For an evergreen explanation, focus on the mechanism rather than the exact day:
- A provider determines the effective holding period for the next settlement.
- If that effective period covers more than one standard overnight interval, the swap posting may scale accordingly.
This is a major failure mode for interpreting swaps: if you look only at one day’s swap credit/debit, it may appear “too large” (or “too small”) because it is covering multiple days.
Material limitations and failure modes
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Market conditions and inputs move: Even without changing your position, the interest inputs and the provider’s mapping from those inputs into swap quotes can change over time.
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Provider conventions change the posted amount: Swap postings depend on contract terms, day-count, rounding, and any provider adjustment. Without the provider’s published swap methodology (or your account’s swap schedule), you cannot reconstruct the exact number from first principles.
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Execution timing matters: The swap can depend on when the trade is executed relative to the provider’s daily cut-off time (server time). A late execution near the cut-off can change whether today’s swap is applied.