Markets affected after US military strike against Iran

Market watchers are bracing for turmoil after the U.S. confirmed it had launched “major combat operations” in Iran, which investors say could have greater market implications than recent geopolitical flare-ups.

US President Donald Trump has said the US military has launched “major combat operations” in Iran.

Several ministries in the southern part of the Iranian capital, Tehran, were targeted, Reuters reported, citing an unidentified Iranian official.

Markets are unaccustomed to absorbing recent geopolitical and economic shocks and headlines, including Trump’s announcement to raise US tariffs on all imports to 15% and the impeachment of former Venezuelan President Nicolas Maduro.

“It definitely has bigger ramifications than Venezuela,” said Florian Wiedinger, co-chief investment officer at Santa Lucia Asset Management.

“Venezuela … is only really relevant to people who care about certain heavy crude,” Wiedinger told CNBC. The country’s heavy, sour crude oil can be challenging to extract, though particularly complex refineries, particularly in the US

“That’s why it’s a big risk. You can expect oil to rise a little bit more violently next week as a result,” he said.

Venezuela currently produces an average of 800,000 barrels of crude oil per day, down from 3.5 million barrels per day, or bpd, in the 1990s.

“Venezuela is a build-up story. (Iran) is a chokepoint story,” said Kenneth Goh, director of private wealth management at UOB Kay Hian in Singapore.

Located in the Gulf between Oman and Iran, the strait is one of the world’s major oil choke points. Crude oil shipments through the Strait of Hormuz in 2025 will be about 13 million barrels per day, roughly 31% of global seaborne crude flows, data provided by market intelligence firm Kpler showed.

In June 2025, when Israel struck Iranian nuclear sites, equities sold off sharply at the open, only to recover after it became clear that the Strait was not deterred.

“That’s the pattern markets will refer to on Monday,” Goh said, adding that there could be a flight to safety with the strengthening US dollar, Japanese yen and a rush to gold.

Other market observers echoed the same. Alicia Garcia-Herrero, chief economist for Asia-Pacific at Natixis, expects a “rough and risk-off” opening on Monday, with global stocks down 1% to 2% or more, US Treasury yields 5 to 10 basis points and oil jumping 5% to 10%.

But there are “no hero bets,” he said, warning that investors should wait for Iran’s response.

Some money managers said risk-off positioning has been built up for weeks, potentially providing some buffer against initial volatility when trading begins.

Wiedinger noted that some cross-asset moves already reflected a “slightly crisis environment,” citing firmer oil and stronger demand for Treasuries in recent weeks.

While markets expected this development, investors are closely watching whether the latest US move remains a short, focused campaign or escalates into a protracted regional conflict.

Quantum Strategy’s David Roche framed the market impact around the period and whether Iran would try to close the Strait of Hormuz. If the conflict is small and contained, the risk-off move and oil spike may be brief, he said.

If it turns out to be a long, three-to-five-week “regime change effort,” investors expect prices to react “rather badly” to widespread friction and a prolonged oil disruption. In such a scenario, Roche told CNBC it would increase its gold holdings to around 15% of its portfolio as a protective hedge.

Iran’s long-term retaliation will have particular implications for Asian markets, dependent on stable energy supplies and trade routes, said Billy Leung, investment strategist at GlobalX ETFs, who expects global stocks to open lower with higher volatility, particularly in high-beta and cyclical sectors.