How tariffs, oil prices and the NZ dollar move NZX and ASX shares

Company results matter, but so do forces no single company controls. A change in oil prices, a new tariff or a move in the New Zealand dollar can lift one group of shares and hurt another on the same day. This guide explains the main forces and how they flow through to NZX and ASX companies.

This is an explanation of general relationships, not a forecast. Every company is different; check its own disclosures about what affects it.

Tariffs and trade tension

Since 2025, the United States has imposed broad tariffs on imports, including from New Zealand and Australia, and trade tension between the US and China has risen and fallen.

Who tends to be exposed:

• Exporters selling into the US, such as manufacturers, medical device makers and food and wine producers, face higher prices for US buyers or thinner margins if they absorb the cost.
• Companies with US manufacturing can be partly protected or even gain against competitors.
• Miners and commodity exporters are hit indirectly when tariffs slow global growth, especially Chinese demand.

Who tends to be insulated: domestic businesses such as electricity generators, airports, supermarkets and telcos, whose customers are mostly local.

The details matter. A company that makes products in New Zealand and sells them in the US is affected differently from one that manufactures in Mexico. Company announcements and investor presentations usually explain their exposure.

Oil and fuel prices

Higher oil prices hurt:

• Airlines, for which fuel is one of the largest costs, although hedging delays the impact.
• Transport and logistics companies.
• Consumers, whose spending power falls, which can weigh on retailers.

Higher oil prices help:

• Energy producers such as Woodside and Santos on the ASX.
• Sometimes alternative energy businesses whose products become relatively cheaper.

Oil is priced in US dollars, so a weaker New Zealand dollar makes fuel even more expensive locally.

The New Zealand and Australian dollar

A weaker local dollar

• Helps exporters, whose foreign sales are worth more once converted. Fisher & Paykel Healthcare, for example, earns most of its revenue overseas.
• Hurts importers and businesses with large foreign-currency costs.
• Makes overseas earnings worth more for companies with offshore operations.

A stronger local dollar

The reverse: exporters' revenue shrinks in local terms, while importers and consumers benefit.

Many companies hedge currency for 12 to 24 months, so the effect on profit often lags the currency move. For New Zealand investors holding ASX shares, AUD/NZD also directly changes the value of the holding. See buying ASX shares from New Zealand.

Interest rates

Lower interest rates tend to help:

• Income stocks such as utilities, infrastructure and property trusts, because their dividends look more attractive when bank deposits pay less, and their borrowing costs fall.
• Highly indebted companies.
• Housing-related businesses, such as building materials companies and retirement village operators.

Higher rates tend to help: banks, whose margins can widen, at least until bad debts rise.

This is a big reason why the NZX, with its heavy weighting to utilities and infrastructure, is sensitive to Reserve Bank of New Zealand decisions. See NZX vs ASX.

China and commodity demand

China is the largest buyer of Australian iron ore and a major market for New Zealand dairy, meat, forestry and tourism. When Chinese growth slows or its property sector weakens:

• Iron ore miners such as BHP, Rio Tinto and Fortescue are directly affected.
• New Zealand food exporters can face weaker prices.
• Tourism and education providers can see fewer visitors.

Conflict and geopolitical risk

Wars and geopolitical shocks usually move markets through energy prices, shipping routes and risk appetite:

• Oil and gas prices often rise, helping energy producers and hurting airlines.
• Gold tends to rise as a safe haven, helping gold miners.
• Defence and cybersecurity businesses can gain.
• Shipping disruptions raise freight costs for importers and exporters.
• Broad risk aversion can hit high-growth and speculative shares hardest.

Putting it together

Most companies are exposed to several forces at once, sometimes in opposite directions. A New Zealand exporter might benefit from a weak New Zealand dollar while suffering from US tariffs. That's why it helps to look at each force separately, then net them out.

Tasman Desk's Outlook page tracks these forces (tariff tension, oil, conflict risk, China demand, interest rates, the trans-Tasman dollars and gold) and shows which companies you follow are most likely to be helped or hurt, with the reasoning in plain English. Its What If page lets you set the probability of scenarios such as an oil spike or new tariffs and see a range of possible outcomes for a company or your whole portfolio.

Frequently asked questions

How do US tariffs affect New Zealand shares?

Exporters that sell into the US can face lower demand or thinner margins, while domestically focused companies such as utilities and supermarkets are largely insulated. Global growth effects can also hurt commodity exporters.

Which ASX shares benefit from higher oil prices?

Oil and gas producers such as Woodside and Santos typically benefit. Airlines, transport companies and fuel-intensive businesses tend to be hurt.

Is a weak New Zealand dollar good for the NZX?

It tends to help exporters and companies with offshore earnings, such as Fisher & Paykel Healthcare, while hurting importers. The overall effect depends on the mix of companies.

Why do NZX shares react to interest rate decisions?

The NZX has a heavy weighting to utilities, infrastructure and property, which are sensitive to borrowing costs and compete with bank deposits for income-seeking investors.