Update: US Equity Indexes Fall as Treasury Yields Rise After Bessent Triples Size of Buyback Program, Worsening Iran War Sends Brent Crude Above $100

05:01 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 as government bond yields jumped after the Treasury Department unveiled plans to triple government debt buybacks to as much as $6 billion and after Brent crude oil futures surpassed $100 a barrel. The Nasdaq Composite declined 0.6% to 26,253.34, the S&P 500 retreated 0.5% to 7,636.36, and the Dow Jones Industrial Average dropped 0.8% to 52,380.66 on Wednesday. All sectors except energy fell, with consumer discretionary, real estate, industrials and utilities among the steepest decliners. Iran is ready for a more intense war and will escalate counterstrikes if the US continues attacking its territory and infrastructure, Bloomberg reported, citing a senior official from the Islamic Republic. Tehran has no intention of backing down in the face of an American naval blockade and attacks on its oil tankers, the official told the news outlet. 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 it attacked 10 ships near the Strait of Hormuz after the US sank five of Tehran's 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. The front-month US West Texas Intermediate crude oil contract surged 3.6% to $96.39 per barrel, and global benchmark North Sea Brent soared 3.5% to $101.34 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 saying the department would at least double the normal amount for already issued securities. As longer-maturity bond yields rise, governments are taking steps to adjust issuance of longer-dated securities, according to Goldman Sachs. The US Treasury said last month it plans to increase buybacks of Treasuries with a maturity of 10 years or more, reducing the maturity profile of US debt stock. Shorter-maturity issuance will finance the buybacks. "It's an effective reduction in the average maturity of issuance," Goldman's George Cole, head of European rates strategy, said in a webinar. "That in and of itself isn't sufficient to change the yield level." Most US Treasury yields rose, with the 10-year yield up 3.7 basis points to 4.84%, close to its highest since late 2023. 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 6.6%, 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 14%, 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. Gold futures were steady at $4,442.4, and silver futures jumped 1.3% to $67.87.