When the US Federal Reserve raises or cuts its benchmark rate, NZ mortgage rates move — sometimes within days. This isn’t coincidence. NZ banks fund their fixed-rate lending in global wholesale markets that price off US interest rate expectations. Understanding the transmission mechanism helps you make better decisions about when to fix and for how long.
NZ fixed mortgage rates are priced off NZ interest rate swaps, which track NZ government bond yields, which in turn are heavily influenced by US Treasury yields. When the Fed cuts rates, US Treasuries rally, NZ bond yields follow, swap rates fall, and NZ banks can offer lower fixed mortgage rates. The link is real but not mechanical — NZ-specific factors (RBNZ OCR, local inflation, NZD/USD) also drive spreads. A Fed cut doesn't guarantee an immediate NZ mortgage rate cut.
The Transmission Chain
NZ fixed mortgage rates → NZ interest rate swaps → NZ government bond yields → US Treasury yields → US Federal Reserve policy
Each link in the chain matters:
Step 1: The Fed sets US short-term rates
The Fed controls the federal funds rate — the overnight rate for US bank-to-bank lending. This rate anchors the entire US yield curve. When the Fed cuts, short-term US rates fall; when it hikes, they rise.
Step 2: US Treasury yields respond
Longer-term US Treasury yields (2-year, 5-year, 10-year) reflect market expectations of where the Fed will take rates over those horizons, plus inflation expectations and a term premium. They don’t move dollar-for-dollar with the fed funds rate, but they’re strongly correlated.
Step 3: NZ bond yields follow
New Zealand government bonds trade in global markets alongside US Treasuries. NZ and US bond yields have historically moved together — not identically, but directionally. When US 2-year and 5-year yields fall sharply (as they did in late 2024), NZ 2-year and 5-year government bond yields also fall.
This happens because:
- Global investors allocate between bond markets; NZ bonds must offer competitive yields
- NZ banks and institutional investors use both markets; the relative pricing stays within a range
- The NZD/USD exchange rate adjusts to absorb some of the difference, but yields converge
Step 4: NZ swap rates follow bond yields
NZ interest rate swaps (agreements to exchange fixed and floating rate cashflows) are priced against NZ government bond yields. When bond yields fall, swap rates fall. NZ banks use swap markets to hedge the interest rate risk on their fixed-rate mortgage books.
Step 5: Banks set fixed mortgage rates from swap rates
A NZ bank offering a 2-year fixed mortgage rate sets that rate at approximately: Swap rate (2-year) + Credit spread + Margin
When swap rates fall, banks can reduce their fixed mortgage rates while maintaining margin.
The Lag and the Disconnect
The transmission isn’t instant or perfect:
- Lag: Bond market moves happen in real time; banks review their mortgage rates periodically (sometimes daily, sometimes less frequently). Rate cuts often lag market moves by days to weeks.
- RBNZ OCR independence: The RBNZ sets its own OCR based on NZ inflation and economic conditions. Floating mortgage rates track the OCR directly; fixed rates track swap markets. The OCR and the Fed can diverge — the RBNZ cut aggressively in 2024 while the Fed was slower to move.
- NZ-specific spreads: NZ banks add a country and credit spread to swap rates. In times of market stress, these spreads widen — so even if swap rates fall, mortgage rates may not fall as much.
- Currency hedging costs: NZ banks that fund offshore face NZD/USD hedging costs. When the NZD is weak, offshore funding becomes more expensive in NZ dollar terms, which can widen spreads.
Historical Examples
2022–2023: Global rate hiking cycle
The Fed raised rates from 0.25% to 5.25–5.5% (the fastest cycle in 40 years). US 2-year yields surged from ~0.75% to ~5.0%. NZ 2-year swap rates rose similarly. NZ 1 and 2-year fixed mortgage rates went from ~2.5% to ~7%+ — closely tracking the global hiking cycle even though the RBNZ started hiking before the Fed.
Late 2024: Fed begins cutting
The Fed cut rates 100bps from September to December 2024. US 2-year yields fell from ~5.0% to ~4.2%. NZ swap rates fell. NZ banks began reducing 1 and 2-year fixed rates — they had reached 7%+ earlier in the cycle and came down to 5.5–6.5% range by early 2025.
2025–2026: Divergent paths
The RBNZ cut aggressively in 2024–2025 (OCR to 3.5%), bringing NZ floating rates down. Fixed rates moved with global markets. Trade war uncertainty in 2025 drove US Treasury rally and NZ bond yield falls — feeding through to modestly lower NZ fixed rates.
What to Watch in 2026
Key indicators that signal where NZ fixed mortgage rates are heading:
| Indicator | What to watch | Where to check |
|---|---|---|
| US 2-year Treasury yield | Closely tracks 1–2 year NZ fixed rates | US Treasury website, Bloomberg |
| RBNZ OCR | Drives NZ floating rates and 6-month to 1-year end | RBNZ.govt.nz |
| NZ 2-year swap rate | The direct input to 2-year fixed mortgage pricing | RBNZ statistics, interest.co.nz |
| Fed funds futures | Market expectation of future Fed rate moves | CME FedWatch tool |
| NZD/USD | Affects offshore funding costs for NZ banks | XE.com, Reuters |
Frequently Asked Questions
If the Fed cuts rates, will my NZ mortgage rate go down?
Probably — eventually. Fed cuts flow through to US Treasury yields, then to NZ bond yields and swap rates, then to NZ bank mortgage pricing. The process takes weeks to months and isn’t perfectly proportional. A 0.5% Fed cut might translate to 0.2–0.4% reduction in NZ fixed rates over 1–3 months, depending on other market conditions.
Does the Fed affect NZ floating rates?
Indirectly. NZ floating rates track the RBNZ OCR directly. The OCR is set by the RBNZ based on NZ inflation and the economy — but the RBNZ is influenced by global rate expectations when setting the OCR. So yes, a Fed cutting cycle eventually pressures the RBNZ to cut the OCR, which lowers floating rates — but the RBNZ makes its own decisions on its own timeline.
Should I fix my mortgage when the Fed is cutting?
If the market has already priced in Fed cuts (bond yields have already fallen, fixed rates already reflect the cuts), fixing now may not give you much extra benefit from further expected cuts. If markets haven’t priced in further cuts, fixing later may capture lower rates. This is a judgement call — no one consistently times rates correctly. Your own financial situation, risk tolerance, and cashflow stability matter more than rate forecasts.
How do I track NZ swap rates?
The RBNZ publishes daily swap rates on its website (rbnz.govt.nz). Interest.co.nz publishes daily NZ bank mortgage rates and tracks swap rate movements. These are the most useful sources for NZ borrowers.