US stock markets today (March 18, 2026): S&P 500, Dow slide as Brent crude nears $110 and inflation fears intensify

US stock markets declined on Wednesday as a sharp rise in global oil prices heightened concerns about inflation and weighed on investor sentiment, even as policymakers prepared to announce their latest interest rate decision.The S&P 500 fell 0.5% and was on course for its first loss this week. The Dow Jones Industrial Average dropped 377 points, or 0.8%, by 11 am Eastern time, while the Nasdaq Composite slipped 0.5%.Markets came under pressure after Brent crude, the international benchmark, surged 6.2% to $109.84 per barrel. Benchmark US crude rose 2.3% to $97.70 per barrel.Oil and natural gas prices have climbed sharply since the onset of the Iran conflict due to disruptions to the energy industry in the Persian Gulf. Iran’s state television said on Wednesday that the country would attack oil and gas infrastructure in Qatar, Saudi Arabia and the United Arab Emirates following strikes on facilities linked to its offshore South Pars gas field.Analysts warned that prolonged disruptions keeping oil and gas prices elevated could trigger a damaging wave of global inflation.A report released earlier in the day showed inflationary pressures in the US had already begun to rise even before the conflict escalated. Wholesale inflation accelerated unexpectedly to 3.4% last month, raising the likelihood that producers may pass on higher costs to households.The data strengthened market expectations that the US Federal Reserve would keep interest rates unchanged following its latest policy meeting, rather than resume rate cuts.Lower borrowing costs could support economic growth and financial markets, and US President Donald Trump has been urging policymakers to cut rates. However, analysts cautioned that easing monetary policy could further aggravate inflation.Investors were also closely watching whether Fed officials would signal the possibility of a rate cut later in 2026. The median projection published in December had indicated that such a move remained on the table.Economic forecasting has become more challenging amid the Iran conflict, which has pushed gasoline prices sharply higher. The average price of gasoline in the US rose overnight to $3.84 per gallon, compared with less than $3 last month.ING Bank analysts Warren Patterson and Ewa Manthey said global oil flows remained constrained despite tentative hopes that Iran could allow more vessels through the Strait of Hormuz, a crucial route for energy shipments. About one-fifth of the world’s crude oil passes through the waterway, which has been largely closed as Iran blocks vessels linked to the US, Israel and their allies.Corporate earnings updates offered mixed signals on Wall Street. Shares of Macy’s rose 4.4% after the retailer reported stronger-than-expected quarterly profit and revenue as part of a turnaround strategy led by chief executive Tony Spring.In contrast, General Mills slipped 1.5% after the food major posted weaker profit for the latest quarter, even as chief executive Jeff Harmening reaffirmed the company’s full-year outlook.In the bond market, Treasury yields edged higher after the wholesale inflation data. The yield on the 10-year Treasury rose to 4.22% from 4.20% late Tuesday and from 3.97% before the Iran conflict began.Overseas markets showed mixed trends. European indices declined following a stronger finish in Asia, reacting to rising crude prices as trading progressed across global time zones. Japan’s Nikkei 225 rallied 2.9% after better-than-expected export data, while South Korea’s Kospi surged 5%.