US stocks extended their selloff on September 15 as higher Treasury yields, surging oil prices and renewed concerns over inflation and government debt weighed on investor sentiment. The combination created a broad risk-off environment across Wall Street, with energy stocks providing one of the few areas of strength as geopolitical tensions raised concerns about global energy supplies.

Treasury Yield Crosses 5% as Rate Expectations Intensify

The benchmark 10-year US Treasury yield moved above 5%, reaching its highest level since 2007. The move extends a sharp repricing in the bond market that has been driven by persistent inflation concerns, heavy government borrowing and expectations that interest rates may remain elevated for longer. Reuters reported that the yield had already crossed 5% on Monday, with investors increasingly focused on the interaction between energy prices, inflation and the US fiscal outlook.

Higher Treasury yields create a significant transmission channel into the broader economy. They can increase borrowing costs for households, corporations and governments while also affecting equity valuations by raising the discount rate applied to future earnings. For companies with substantial financing requirements, including businesses involved in AI infrastructure and data-center development, the shift in capital costs has become an increasingly important market consideration.

Oil Rally Adds to Inflation Pressure

Energy markets provided another source of pressure. West Texas Intermediate crude settled 4.4% higher, while Brent crude gained 2.9%, as expanding Middle East hostilities and attacks on Saudi Arabian energy infrastructure heightened concerns over supply. Diesel futures also closed at a record high, reinforcing the potential for energy costs to feed into transportation and broader consumer prices.

The oil rally is particularly significant for monetary policy because sustained energy inflation can complicate the Federal Reserve’s efforts to control price pressures. Reuters reported that markets were pricing in a more than 95% probability of a 25-basis-point rate increase at the September 16 decision, compared with substantially lower expectations one month earlier. Economists surveyed by Reuters had also shifted strongly toward a rate increase following recent inflation data.

Equities Face Multiple Sources of Pressure

The Dow Jones Industrial Average fell 0.63% to 52,090.46, while the S&P 500 declined 0.45% to 7,585.51. The Nasdaq Composite fell 0.77% to 25,983.58. Nearly every sector came under pressure except energy, illustrating how the rise in oil prices simultaneously supported producers while increasing concerns about inflation and economic costs across the wider market.

Technology stocks faced an additional challenge from growing questions about the sustainability of AI-related capital spending. Reuters reported that global AI spending is expected to approach $800 billion in 2026, with major technology companies projected to spend nearly $795 billion on capital expenditures this year. Concerns that slower AI development or increased regulation could affect infrastructure spending have therefore added another layer of uncertainty to an already challenging market environment.

Looking ahead, investors will closely monitor the Federal Reserve’s September 16 decision and its guidance on future rate increases, alongside oil prices, Treasury yields and developments in the Middle East. The durability of the 5% Treasury yield level could be particularly important for equity valuations and corporate financing conditions. Markets will also assess whether the recent AI-related concerns translate into measurable changes in capital expenditure plans or remain primarily a valuation and sentiment issue. Together, monetary policy, energy prices and AI investment trends will remain central to the direction of global markets in the coming sessions.