Update: US Equity Indexes Drop as Crude Oil Tops $100 Mark Amid Worsening Iran War, Yields Surge After Treasury Triples Government-Debt Buybacks

01:36 PM EDT, 09/09/2026 (MT Newswires) -- (Updates with index/price moves, macroeconomic data, comments and company/geopolitical news from the first paragraph.) US equity indexes slid after Brent crude oil futures crossed $100 a barrel and a surge in government bond yields wiped the shine off the Treasury Department's move to triple government debt buybacks to as much as $6 billion. The Nasdaq Composite declined 0.6% to 26,260.2, the S&P 500 retreated 0.4% to 7,641.5, and the Dow Jones Industrial Average dropped 0.5% to 52,522.6 after midday Wednesday. All sectors except energy fell, with consumer discretionary, real estate, industrials and utilities among the steepest decliners. The Iranian Revolutionary Guard Corps plans to declare a restricted zone stretching from Chabahar into parts of the Gulf of Oman and the Arabian Sea, Al Jazeera, a Middle Eastern broadcaster, reported. Any vessel entering this area will face sanctions, it said. The Strait of Hormuz accounted for about a fifth of global oil and gas flow daily before the Iran war. Iran said on Wednesday it had attacked 10 ships near the Strait of Hormuz after the US sank five Iranian oil tankers, in the biggest declared wave of tit-for-tat attacks on shipping by both sides since the start of the six-month-old war, Reuters reported. "Oil prices will be higher for longer with no end in sight for what remains Iran's strategy of managed irresolution through US midterms," Derek Holt, the head of capital market economics at Scotiabank, said in a note. The front-month US West Texas Intermediate crude oil contract surged 2.9% to $95.68 per barrel, and global benchmark North Sea Brent soared 2.8% to $100.68 per barrel. The Treasury Department plans to buy back up to $6 billion of government debt, CNBC reported. The move triples the normal buyback operation, following an announcement Aug. 19 from Treasury Secretary Scott Bessent that the department would at least double the normal amount for already-issued securities. Most US Treasury yields rose, with the two-year up 2.5 basis points to 4.42%. The 10-year yield jumped 3.1 basis points to 4.84%, trading close to its highest since late 2023. Treasury yields rose despite the increased buyback announcement, as some on Wall Street expect even bigger repurchases, according to CNBC. Gold futures rose 0.6% to $4,464.00, and silver futures jumped 2.8% to $68.90. In company news, Meta Platforms (META) launched a new personal artificial intelligence agent called Muse AI, which can send emails, book travel plans, take on goals, and continue working after users close the app. Shares advanced 6.2%, among the top gainers on the S&P 500 and the Nasdaq. Casey's General Stores (CASY) fiscal Q1 same-store sales growth slowed and missed Wall Street estimates, taking the shine off earnings and revenue beats. Shares sank more than 15%, the steepest decliner on the S&P 500. In economic news, Redbook US same-store sales surged 8.3% from a year earlier in the week ended Sept. 5, after a 9.6% year-over-year increase in the previous week.