How a US-Iran War Could Affect Global and South African Stock Markets

Geopolitical tensions are never comfortable to watch. When headlines mention conflict between the United States and Iran, investors understandably feel uneasy.

But how does a potential US-Iran war actually affect the stock market? And more importantly, what could it mean for investors here in South Africa?

Let’s unpack it calmly and clearly.

Why Markets React to Conflict

Financial markets dislike uncertainty. 

When the risk of war rises, investors tend to move quickly. They sell riskier assets and shift money into what are seen as “safe havens” such as gold, the US dollar, and government bonds.

This often leads to:

• Short-term market volatility

• Sharp swings in share prices

• Sector rotation (some industries rise, others fall)

It is important to remember that markets usually react first and assess later. Initial moves can be emotional rather than rational.

Oil Prices: The Real Pressure Point

If there is one channel through which a US-Iran conflict would affect markets most strongly, it is oil.

Iran sits near the Strait of Hormuz, one of the world’s most important shipping routes for crude oil. Around a fifth of global oil supply passes through this narrow stretch of water. Any threat to this route can push oil prices sharply higher.

Why Higher Oil Prices Matter

When oil rises:

• Transport becomes more expensive

• Manufacturing costs increase

• Inflation tends to rise

• Consumers have less disposable income

Higher energy costs ripple through almost every part of the economy. Businesses face margin pressure, and households feel the squeeze.

For global stock markets, this often means pressure on consumer and industrial sectors, while energy producers benefit.

Winners and Losers in the Market

Conflict rarely hurts all shares equally. In fact, some sectors often perform well.

Likely Beneficiaries

• Oil and energy companies

• Defence contractors

• Gold producers

• Commodity exporters

Energy producers benefit from higher oil prices. Gold tends to rise because investors see it as a store of value during uncertain times.

Likely Under Pressure

• Airlines and travel companies

• Retailers

• Consumer discretionary stocks

• Oil-import dependent economies

Higher fuel costs directly hurt airlines. Consumers may also cut spending if fuel and food prices rise.

This is why we often see “rotation” rather than a full market collapse.

What Does This Mean for South Africa?

South Africa feels global shocks quickly, especially through commodities, inflation and the currency.

1. Fuel Prices and Inflation

South Africa imports a large portion of its fuel. If global oil prices rise, local petrol and diesel prices follow. That feeds directly into inflation.

Higher inflation can affect:

• Household budgets

• Consumer spending

• Business costs

• Interest rate expectations

2. The Rand

During global uncertainty, investors tend to favour the US dollar. This can weaken emerging market currencies, including the rand.

A weaker rand makes imports more expensive, which can further increase inflation.

3. The JSE’s Unique Structure

The Johannesburg Stock Exchange is heavily weighted towards resource companies. That can sometimes work in South Africa’s favour.

If commodity prices rise, mining and energy shares may perform well. Gold miners, in particular, often benefit during geopolitical tensions.

However, retailers and banks may feel pressure if local consumers tighten their belts.

Inflation and Interest Rates

One of the biggest risks from a prolonged conflict is sustained higher oil prices. That could keep inflation elevated globally.

If inflation rises:

• Central banks may delay interest rate cuts

• Borrowing costs could remain higher for longer

• Economic growth may slow

For South Africa, the South African Reserve Bank would need to balance inflation risks with economic growth. Rate decisions could become more complicated if imported inflation rises sharply.

The worst-case scenario would be a period of slow growth combined with rising prices, sometimes called stagflation. However, that would require a prolonged and severe disruption to global energy supply.

What History Tells Us

Looking back at previous geopolitical crises can be reassuring.

Markets often:

• Fall sharply when conflict begins

• Stabilise once the scope becomes clearer

• Recover if the economic impact is contained

Even during major events such as the Gulf War or more recent Middle East tensions, market declines were often temporary.

The key driver has almost always been energy supply disruption. If oil flows continue relatively normally, market damage tends to be limited.

Short-Term Volatility vs Long-Term Investing

In the short term, we can expect:

• Increased volatility

• Stronger gold prices

• Oil price swings

• Currency fluctuations

In the long term, however, markets are driven by earnings, growth, and economic fundamentals.

Unless a conflict significantly disrupts global trade or energy supply for an extended period, markets usually adapt.

Practical Guidance for Investors

Times like these test investor discipline. Here are some practical reminders:

• Avoid panic selling. Emotional decisions rarely lead to good outcomes.

• Maintain diversification across sectors and geographies.

• Ensure your portfolio reflects your risk tolerance.

• Keep an eye on inflation and interest rate trends.

• Review, but do not abandon, your long-term strategy.

Periods of uncertainty often create both risks and opportunities. A well-balanced portfolio is designed to withstand short-term shocks.

So, Should Investors Be Worried?

Concern is natural. Panic is not necessary.

A US-Iran conflict would likely increase market volatility, especially through higher oil prices and shifts in investor sentiment. South Africa could feel the impact through fuel prices, inflation and currency weakness.

However, markets are resilient. History shows that unless energy supply is severely disrupted for a prolonged period, the long-term impact on diversified investors is often limited.

The most important response is not reaction, but preparation. Staying diversified, disciplined and informed remains the best strategy during uncertain times.