Oil prices are rising, and stock markets are dropping worldwide Wednesday after President Donald Trump raised doubts about the temporary truce in the war with Iran.The S&P 500 fell 1.0 per cent after Trump said the agreement to pause fighting was “over” though he added that he would allow negotiations to continue. The Dow Jones Industrial Average was down 831 points, or 1.6 per cent, as of 11:45 a.m. Eastern time, and the Nasdaq composite was 1.0 per cent lower.The action was stronger in the oil market, where the price for a barrel of Brent crude climbed 8 per cent to US$80.09. That is well below its peak from earlier in the war when the price for the most actively traded contract reached nearly US$120. But the jump is unsettling because oil prices had just dropped back to where they were before the war.The worry is that a continuation of the war will block the Strait of Hormuz and prevent the delivery of crude from the Persian Gulf to customers worldwide. That could worsen inflation, which economists expected would ease with oil prices, and, in turn, force the Federal Reserve and other central banks to raise interest rates.Higher rates can keep a lid on inflation, but they also slow the economy and hurt prices for all kinds of investments.Losses for stock markets in Europe accelerated, and oil prices climbed immediately after Trump said, “For me, I think it’s over” about the status of the ceasefire. He added that US representatives can continue negotiations, “but I think they’re wasting their time”.Trump later said the United States was preparing for another night of strikes against Iran.On Wall Street, companies with big fuel bills fell sharply. American Airlines lost 5.9 per cent, and United Airlines fell 4.9 per cent.Stocks of companies in the housing industry were also weak. They were hurt by worries that rising Treasury yields in the bond market will lead to higher rates for mortgages and chill the industry.Builders FirstSource, which sells countertops, windows and other building supplies, fell 6.6 per cent. Homebuilders PulteGroup fell 4.6 per cent, and D.R. Horton sank 4.5 per cent.Drops of 4.0 per cent for Sherwin-Williams and 3.3 per cent for Home Depot were two of the biggest reasons the Dow was heading towards its worst loss in about a month.Helping to offset those losses was a steadying for some influential stocks in the artificial-intelligence industry. They have been under pressure in recent weeks on worries that their prices shot too high and that AI may not produce enough productivity and profits to make all the investments in chips and data centres worth it.Their swings carry a lot of weight on Wall Street because AI stocks have grown into some of the US market’s biggest, giving their movements more effect on the S&P 500 than other stocks.Nvidia rose a modest 0.3 per cent, for example, and was the second-strongest force pushing upwards on the S&P 500 because it is the largest stock on Wall Street.The strongest push upwards on the market came from Broadcom, which rose 4.1 per cent. Apple announced a multiyear commitment with Broadcom to design and produce custom components for its products. Apple said the agreement’s value could top US$30 billion.In the bond market, Treasury yields rose with the price of oil. The yield on the 10-year Treasury climbed to 4.59 per cent from 4.55 per cent late Tuesday and from just 3.97 per cent before the war with Iran began.In stock markets abroad, losses for European markets worsened after Trump made his comments, and Germany’s DAX lost 2.2 per cent.In Asia, South Korea’s Kospi dropped 5.3 per cent and continued its sharp swings amid duelling worries and euphoria about the AI stocks that dominate its market.Hong Kong’s Hang Seng index was an outlier and rose 3.0 per cent.Shares that trade in Hong Kong of Chinese AI startup Zhipu, known also as Z.ai and traded as Knowledge Atlas Technology, jumped 13.4 per cent.A six-month lock-up period for “cornerstone” investors following its January trading debut in Hong Kong expires this week. China National Radio reported late Tuesday that nearly 70 per cent of Zhipu’s cornerstone investors are committed to stay on despite previous worries that the lock-up period expiration could trigger a sell-off.Zhipu’s share price has risen more than 1,300 per cent since its debut.