Wall Street's three main stock indexes ended lower. Concerns that the United States could intervene militarily in Iran and unease after the U.S. Supreme Court did not deliver a ruling on whether tariffs are illegal added to uncertainty. Losses narrowed quickly late in the session after U.S. President Donald Trump suggested he might not strike Iran.

On Jan. 14, the Dow Jones Industrial Average closed down 42.36 points, or 0.09 percent, at 49,149.63 on the New York Stock Exchange (NYSE).

The S&P 500 fell 37.14 points, or 0.53 percent, to 6,926.60, while the Nasdaq Composite dropped 238.12 points, or 1.00 percent, to end at 23,471.75.

The S&P 500 fell for a second straight day for the first time in 2026 as the "Magnificent 7" stocks all weakened.

Overall, military tension surrounding Iran was seen as driving the stock market.

The main indexes widened losses quickly after the open. That followed continued reports in foreign media that a U.S. military strike on Iran was imminent.

In Europe, there was speculation that U.S. military intervention in Iran's political situation was likely and could begin within 24 hours. An Israeli official also said Trump appeared to have decided on military action.

Amid the tense mood, the Nasdaq at one point extended losses to as much as 1.7 percent.

In the afternoon, Trump said, "I heard that the killing has stopped in Iran," and added, "I believe there are no plans for mass executions at this time," easing tensions. International oil prices turned lower, down 2.5 percent, and stock indexes quickly pared losses.

All mega-cap technology companies with market capitalisation of more than $1 trillion fell.

Nvidia fell 1.44 percent. Microsoft, Amazon and Meta posted declines of more than 2 percent. Broadcom slid 4.15 percent.

Energy companies such as Exxon Mobil and Chevron extended gains. Rising oil prices amid heightened Iran tensions raised expectations of a spillover benefit.

Technology shares weighed on the broader market due to negative news from China. Nvidia slipped 1 percent after Reuters reported that Chinese customs issued a guideline not to allow imports of the H200 chip.

Broadcom and Fortinet also fell after reports that the Chinese government instructed domestic companies to stop using U.S.- and Israeli-made security software.

Uncertainty was set to persist at least until next week after the U.S. Supreme Court did not issue a ruling in a lawsuit related to Trump's tariff policy.