Highlights

  • Brent crude reached US$84.22 a barrel after its biggest one-day jump since 2020, driven by an intensifying standoff between the United States and Iran over the Strait of Hormuz.
  • ANZ-Roy Morgan weekly inflation expectations rose to 5.7 per cent, and money markets were pricing roughly 50 per cent odds of a US Federal Reserve rate rise in July 2026.
  • Higher-for-longer interest rates cut both ways for banks: they may support net interest margins but can also raise funding costs, slow credit growth and strain borrowers.
  • Market commentary reported on 12 July 2026 flagged mortgage pricing wars and a potential spike in business loan losses as two key risks for the sector, while fund managers have warned of soft bank earnings growth.

Shares in Australia’s four major banks — Commonwealth Bank of Australia (ASX:CBA), National Australia Bank (ASX:NAB), ANZ Group Holdings (ASX:ANZ) and Westpac Banking Corporation (ASX:WBC) — traded lower in morning trade on 14 July 2026, helping to drag the S&P/ASX 200 lower to 8,778 by 10.17am AEST.

The pullback coincided with a sharp rebound in global oil prices, which revived inflation concerns and firmed expectations that interest rates in major economies could stay higher for longer. No single factor fully explains any share price move, but the inflation-and-rates channel was the dominant theme in market discussion on the day.

This article explains the oil-to-inflation-to-rates transmission and why it cuts both ways for bank margins, credit growth and loan quality.

Why did the major bank shares move?

At 10.17am AEST on 14 July 2026, Commonwealth Bank was lower, NAB had moved lower, ANZ was lower and Westpac had moved lower. Given their large index weight, the banks were among the heaviest drags on the benchmark, with six of the market’s eleven sectors weaker.

The backdrop was a dramatic move in energy markets. Brent crude rose a further 1.1 per cent to US$84.22 a barrel on Tuesday morning AEST after jumping 9 per cent overnight — its biggest one-day increase since 2020 — while US benchmark WTI had soared 9.4 per cent on Monday, US time.

The surge followed an intensifying standoff between the United States and Iran. US President Donald Trump said the US would restart a naval blockade of Iranian ships transiting the Strait of Hormuz — a chokepoint through which roughly a fifth of global oil supply typically passes — and charge other cargo a 20 per cent fee for passage.

The bank share falls were modest and coincided with these events rather than being demonstrably caused by them; separate fund manager warnings about soft bank earnings growth may also have weighed.

How could higher oil prices affect inflation?

Oil feeds into consumer prices through several channels. Petrol and diesel are directly measured in the consumer price index, while fuel is also a cost input for freight, airlines, agriculture and manufacturing, so sustained increases can gradually push up prices across the economy.

Perhaps as importantly, visible petrol price rises can lift inflation expectations — what households believe inflation will be — which can influence wage claims and pricing behaviour. The ANZ-Roy Morgan weekly measure of inflation expectations rose 0.3 percentage points to 5.7 per cent in the week to 12 July 2026, while consumer confidence, at 75.3, remained historically weak.

Central banks watch these dynamics closely. In the United States, money markets were pricing roughly 50 per cent odds of a Federal Reserve rate rise in July 2026, with June CPI data and new Fed chairman Kevin Warsh’s first congressional appearance due later on Tuesday, US time.

In Australia, Reserve Bank assistant governor Sarah Hunter had noted that economic growth would need to slow further to return inflation to the 2–3 per cent target band. If oil prices stayed elevated, markets may reason that rate cuts become less likely — or rate rises more likely — in both economies.

differ

The four majors share a common macro backdrop but carry different exposures. Commonwealth Bank is Australia’s largest bank, holds the biggest home loan book and has typically traded at a premium multiple to its peers.

NAB is the country’s biggest business bank, which makes trends in business credit demand and business loan quality particularly relevant to its earnings mix. ANZ has a stronger institutional focus and expanded its retail presence through the acquisition of Suncorp Bank in 2024.

Westpac is weighted towards consumer banking and is part-way through its UNITE technology simplification program. These differences mean an inflation-and-rates shock would not affect all four banks equally, even if their shares often move together on macro news.

What could higher interest rates mean for bank margins?

The net interest margin (NIM) — the difference between what a bank earns on loans and investments and what it pays for deposits and other funding, expressed against interest-earning assets — is the core driver of major bank revenue.

Higher rates can support margins. Banks typically do not pass the full extent of rate rises through to all deposit accounts, and returns improve on the so-called replicating portfolio — the pool of low-cost deposits and shareholder capital that banks invest at prevailing market rates.

But the same environment can squeeze margins from other directions. Wholesale funding becomes more expensive, competition for term deposits and savings balances tends to intensify, and demand for new loans generally cools as borrowing costs rise.

The net effect for each bank depends on the balance of these forces and on competitive behaviour in the mortgage market, so any simple ‘higher rates are good for banks’ claim deserves caution.

What are the risks from mortgage competition?

Market commentary reported on 12 July 2026 identified mortgage pricing wars as one of two key risks facing the Australian banks. A pricing war describes periods when lenders compete aggressively for home loan customers through discounted rates, cashback offers and broker incentives.

Such competition can compress the margin earned on new and refinanced loans below the level earned on the existing book. If rates stay higher for longer, more borrowers may shop around to reduce repayments, increasing churn and handing pricing power to customers.

The stakes differ across the majors. Commonwealth Bank and Westpac carry the largest consumer mortgage exposures, so sustained discounting could weigh more heavily on their margin outcomes, while NAB’s business tilt and ANZ’s institutional book provide partial offsets. These are possibilities rather than predictions, and competitive intensity can change quickly.

What could happen to business and consumer credit quality?

The second risk flagged in the 12 July 2026 commentary was a potential spike in business loan losses amid volatile oil prices, slower growth and higher rates. Banks provision for expected losses, but a sharper-than-expected deterioration could hit profits directly.

Recent credit data points to an uneven picture. Equifax figures for June 2026 showed business loan demand higher year on year — below its twelve-month average — while asset finance demand moved lower. Large businesses lifted loan enquiries by 7.8 per cent, against just 0.5 per cent growth for small and medium enterprises, and SME asset finance demand moved lower nationally.

That divergence may suggest smaller businesses are becoming more cautious about investing, which could matter for NAB in particular as the biggest business lender, though all four majors carry meaningful business exposures.

On the consumer side, weak confidence at 75.3, rising fuel costs and elevated repayments could squeeze household budgets. Higher petrol prices act like a tax on discretionary spending, and stretched borrowers are a standard early-warning channel for mortgage arrears.

Valuations after the 2024–2026 bank rally

Context matters for how bank shares respond to macro news. Australian bank share prices had been elevated relative to their historical multiples following a strong rally across 2024 to 2026, with Commonwealth Bank in particular trading at a premium to peers.

Elevated starting valuations can amplify sensitivity to disappointing news, because more optimism is already reflected in prices. Fund managers were separately warning that soft bank earnings growth, alongside the local market’s limited exposure to artificial intelligence themes, could hold back the Australian sharemarket.

None of this means bank shares must fall further, but it may help explain why modest macro shifts appeared to move the sector on 14 July 2026.

What should bank investors watch?

Several signposts could shape the outlook for the major banks over the coming weeks and months.

drove Brent to US$84.22 a barrel on 14 July 2026.

  • US June CPI data and the Federal Reserve’s July 2026 meeting, where markets priced roughly 50 per cent odds of a rate rise.
  • Reserve Bank of Australia commentary and the weekly ANZ-Roy Morgan inflation expectations series, last at 5.7 per cent.
  • Bank reporting updates covering net interest margins, deposit competition, mortgage arrears and business loan impairments.
  • Mortgage pricing behaviour, including discounting and cashback offers, and monthly credit demand data such as the Equifax series.

A balanced view for bank shareholders

The declines in Commonwealth Bank (ASX:CBA), NAB (ASX:NAB), ANZ (ASX:ANZ) and Westpac (ASX:WBC) on the morning of 14 July 2026 were modest, and one session’s trade says little about the sector’s longer-term direction.

What the day illustrated is the transmission chain investors may want to understand: geopolitical supply shocks can lift oil, oil can lift inflation and inflation expectations, and that can keep interest rates higher for longer — an environment with genuinely two-sided consequences for bank margins, credit growth and loan losses.

With sector valuations elevated after a multi-year rally and commentators flagging mortgage competition and business credit quality as key risks, the banks may remain sensitive to inflation and rates news. As always, figures cited here are as reported at the dates indicated and are subject to change.