U.S. stock futures tumble as oil surges on Iran weekend turmoil

U.S. stock futures slipped and oil prices jumped after a series of weekend developments tied to the Iran conflict reignited geopolitical uncertainty. Markets moved from a brief period of risk-on sentiment back toward caution as supply concerns resurfaced.

The sequence began with mixed messages over the status of the Strait of Hormuz: an announcement that the waterway had been reopened on Friday helped push equities higher, but reports over the weekend that Iran had reimposed controls and that some vessels were turned back reversed that effect. Reuters reported Brent crude futures rose about 7% to roughly $96.85 a barrel in early Asian trading, while S&P 500 futures fell around 0.9%. U.S. authorities also said they seized an Iranian-flagged cargo vessel that tried to breach a blockade, adding to market nerves.

The moves came on the heels of a three-week rally that had driven the S&P 500 to new intraday and closing records after the initial ceasefire signals and Friday’s reopening news. That earlier optimism briefly eased inflation fears by lowering energy prices, but the weekend’s reversal quickly brought those concerns back to the fore and pushed investors toward safe-haven assets and the dollar. Currency markets also reflected the shift, with the euro and yen retreating against the dollar.

The Strait of Hormuz remains a critical chokepoint for global crude shipments, so any renewed disruption carries outsized implications for supply, inflation and central bank policy outlooks. Higher oil would feed through to consumer prices and could complicate central bank decisions already balancing growth and inflation; conversely, any sustainable de-escalation would likely relieve pressure on energy markets and risk assets.

Market strategists say volatility is likely to persist while diplomatic dialogue and on-the-ground events remain unsettled. Some analysts expect equities to give back a portion of last week’s gains if the strait remains closed or if attacks on shipping continue, while energy producers could see earnings upgrades if higher prices persist. Key near-term variables to watch include shipping traffic updates through Hormuz, official statements from U.S. and Iranian negotiators, and upcoming corporate earnings that will test investor risk appetite.