Matched horizons · expected policy paths · futures basis
6S Yield Spreads: Curves, Carry and Measurement
The SNB–Fed policy-rate gap can remain unchanged while 6S reprices. Markets may revise the expected path three months ahead, long-bond term premium may change, hedging demand may move the cross-currency basis, or a risk shock may alter CHF and USD demand. A single observed yield subtraction is not “the” differential.
- Horizon
- Match the thesis
- Instrument
- Match conventions
- Change
- Prefer aligned repricing
- Claim
- Conditional mechanism
Define before subtracting
Choose Comparable Curve Points for the Decision Horizon
Subtracting a Swiss policy rate from a U.S. ten-year yield mixes credit-free instruments, maturities and economic meanings. The choice must follow the hypothesis, not whichever series makes the chart persuasive.
| Question | Candidate evidence | Required controls | Do not call it |
|---|---|---|---|
| Near policy path | Swiss secured overnight / money-market measures and comparable U.S. policy-sensitive instruments | Accrual convention, tenor, credit, liquidity and timestamp | A pure policy expectation without decomposition |
| Government curve | Swiss Confederation and U.S. Treasury observations at matched maturities | Closing clocks, term premium, inflation and market liquidity | Carry earned by a 6S position |
| Real-return view | Nominal curves plus separately defined inflation expectations | Different index structures, liquidity and model uncertainty | An observed risk-free real spread |
| FX hedge cost | Spot, forward/FX swap and matched funding rates | Bid/ask, tenor, basis, collateral and balance-sheet cost | Covered parity without transaction terms |
A curve is a bundle of expectations and premia
Separate the Expected Policy Path From Other Yield Components
A yield can rise because expected short rates rise, expected inflation changes, real growth strengthens, term premium increases, liquidity worsens or credit risk changes. The same yield movement can therefore carry opposing CHF implications.
Freeze the pre-event curves
Capture Swiss and U.S. instruments on comparable clocks before the information arrives.
Measure changes by horizon
Compare short, intermediate and long segments without mixing levels and changes.
Attach candidate causes
Use primary policy, inflation, growth and supply information; mark unresolved residuals.
Test the relative move
Ask which curve repriced more and whether CHF breadth confirms the registered horizon.
The SNB's implementation guidance explains how it seeks to keep short secured franc rates close to its policy rate. The FOMC sets its current target range. Neither current setting reveals the entire expected future path.
Futures are dated instruments
Carry Is Not the Posted Policy-Rate Difference
A 6S futures price reflects spot, time to maturity and the market's financing and hedging conditions. A trader does not mechanically collect the SNB rate minus the federal funds rate by holding one futures contract.
Pricing mechanism
Forward relationship and basis
Under idealized covered-interest-parity conditions, spot, forward and matched funding rates are linked. In practice, bid/ask, collateral, credit, balance-sheet constraints and cross-currency basis affect executable pricing.
Position return
Mark-to-market plus implementation
A futures position realizes price changes and daily settlement, with commissions, spread, slippage, collateral opportunity cost, roll and possible delivery exposure. Currency movement can overwhelm gradual carry.
Record the exact 6S delivery month and remaining tenor; do not use an eternal continuous symbol as the traded object.
Keep futures-minus-spot behavior separate from the CHF/USD spot move.
FX swap and forward pricing can reflect balance-sheet demand beyond posted cash rates.
Closing one expiry and opening another is an execution event with two books and possible slippage.
The BIS paper Covered interest parity lost: understanding the cross-currency basis provides institutional background on why funding and hedging demand can produce a basis. It does not provide a current 6S trade signal.
Rates are one channel among several
Risk, Intervention and Liquidity Can Overwhelm the Spread
Do not declare the rate mechanism active merely because both curves and 6S moved. The same event can create common responses without a causal chain from spread to currency.
Common global shock
Energy, growth or inflation news moves both curves, USD and CHF through several channels at once.
Safe-haven demand
Portfolio reallocation or liability reduction changes CHF demand independently of expected carry.
SNB intervention constraint
Communication or operations may resist rapid appreciation even when the relative-rate configuration appears supportive.
Market microstructure
Rolls, thin depth, forced hedging and gaps can move the futures basis without a stable macro interpretation.
Inference boundary: rates may contribute to repricing when the registered relative curve changes first and independent FX evidence follows. A predictive claim still requires an out-of-sample test.
Reproducible measurement
Use a Curve-Relative Measurement Protocol
This protocol produces an auditable state, not a direction forecast. “Unknown” is required when any core input is stale or non-comparable.
Yield-spread state record
- Hypothesis
- Named Swiss and U.S. instruments, maturity, transformation and expected 6S relationship.
- Clock
- Source timestamps, timezones, publication lags, holidays and event-window endpoints.
- Curves
- Pre/post levels and changes, with policy, inflation, term-premium, credit and liquidity caveats.
- FX evidence
- CHF/USD spot, non-USD CHF crosses, broad USD controls and active 6S basis.
- Execution
- Delivery month, spread, depth, latency, slippage, roll status and invalidation level.
- Output
- Confirmed candidate mechanism, mixed, rejected or unidentifiable—never guaranteed direction.
This article does not estimate a coefficient, optimal maturity, threshold, lead-lag, hit rate or profitability. Those require synchronized point-in-time data, predeclared choices, robustness checks and later validation after costs.
Sources, methods and editorial disclosure — reviewed August 21, 2026
- Swiss National Bank data portal, interest rates, yields and foreign-exchange market for official Swiss series, frequencies and definitions.
- Swiss National Bank, questions and answers on monetary-policy implementation for the policy rate, SARON and implementation framework.
- Federal Reserve, H.15 Selected Interest Rates for official U.S. series and methodological notes.
- Federal Reserve, 2026 FOMC calendar and meeting materials and SNB policy-decision archive for primary policy-path context.
- Bank for International Settlements, Covered interest parity lost: understanding the cross-currency basis for basis, hedging-demand and balance-sheet mechanisms.
- CME Group, FX Product Guide 2026 for 6S quotation, contract unit, tick and physical-settlement context; full mechanics remain with the site's specification guide.
Sources and methods were reviewed August 21, 2026. The article distinguishes curve facts, pricing mechanisms, conditional inference and trading applications. It reports no predictive spread model or performance result.