Wall Street closed sharply lower on Thursday, ending a brief rebound as Treasury yields moved higher again and rising oil prices added pressure to an already unsettled market.

The S&P 500 fell 64.33 points, or 0.83 percent, to 7,643.65. The Nasdaq Composite dropped 272.67 points, or 1.04 percent, to 26,058.42. The Dow Jones Industrial Average shed 693.04 points, or 1.30 percent, to finish at 52,770.01.

The session reversed much of the optimism from Wednesday, when the Treasury Department announced that it would more than double its buyback operations covering 10-, 20-, and 30-year debt. Such operations, in which the Treasury repurchases its own outstanding securities, have generally been aimed at supporting trading liquidity in older, harder-to-trade issues. Traders interpreted the larger purchases of longer-dated securities as potentially inflationary in the context of already ample dollar liquidity, and yields rose back across the curve.

The 10-year Treasury yield had touched a 20-month high of 4.75 percent earlier in the week before easing, while the 30-year yield fell back below 5.2 percent after reaching a 19-year high near 5.34 percent. The move in long-dated yields has coincided with a rising term premium, the extra compensation investors demand for holding longer-dated debt rather than rolling shorter maturities. Higher long-term yields also feed through to borrowing costs on mortgages and corporate debt and lift the risk-free return that bonds offer against equities, a dynamic that can tighten financial conditions independently of the Federal Reserve's policy rate.

Energy markets added to the pressure. Brent crude rose toward 93 dollars a barrel, up 1.52 percent on the day and more than 4 percent for the week, as uncertainty in the Middle East continued to support prices. The standoff between Washington and Tehran over the Strait of Hormuz showed no sign of easing. The strait, roughly 21 miles wide at its narrowest point, carries about a fifth of the world's traded oil, making even the threat of disruption there a long-standing concern for global energy markets. President Trump also said the United States had entered economic war against Iran, prolonging blockades of tankers crossing the Persian Gulf.

Individual stocks amplified the broader macro-driven decline. Walmart sank about 8 percent, its sharpest single-session drop in four years, after second-quarter sales missed expectations. As the largest US retailer, Walmart is widely read as a gauge of American consumer health, and household spending makes up roughly two-thirds of US economic output, so its results draw attention well beyond a single stock. Banks including JPMorgan and Wells Fargo also weakened as short-dated Treasury securities sold off. AI hyperscalers were mostly lower after OpenAI's results were viewed as tepid relative to the pace of growth at rival Anthropic.

The moves capped a volatile week for US equities, with Middle East tensions, a rising term premium on government debt and mixed corporate earnings repeatedly driving swings in sentiment. With the standoff between Washington and Tehran over the Strait of Hormuz still unresolved and bond markets continuing to digest the scale of the Treasury's intervention, traders appeared likely to remain cautious heading into Friday and next week.