US stock futures started September on a weak note, with an uptick in oil prices pushing global bond yields higher and bolstering bets on further interest rate hikes by major central banks this month. As of 8:00 a.m. in New York, futures on the S&P 500 were down 0.6%, while Nasdaq 100 futures dropped 1.2%, with chip and software stocks sliding in pre-market trading. Dow Jones futures also declined by 0.5%.

A global selloff in bonds was underway, particularly pronounced in Asia, where the yield on Japan's 10-year government bond climbed to its highest level this century. This followed a renewed weakening of the yen, prompting US Treasury Secretary Scott Bessent to urge the Bank of Japan to tighten policy. In the US, Treasuries fell across the board, pushing the 10-year yield to its highest level since January 2025. The 30-year yield continued to hold above 5%, marking its longest such stretch since 2006.

Persistent disruptions to energy shipments through the Strait of Hormuz helped push Brent crude above $92 a barrel. Amid the latest escalation in the Middle East, maritime security consultancy Marisks reported that two supertankers were struck by unidentified projectiles while transiting the waterway.

"Equity investors should be more worried about rising long-term bond yields, especially in the US," noted Joachim Klement, a strategist at Panmure Liberum. "Persistent inflation pressures, along with Kevin Warsh's notably hawkish stance at Jackson Hole last week, suggest yields could continue to trend higher."

The risk-off move at the start of September also casts a shadow over the S&P 500, which historically faces its toughest month of the year. Data shows that over the past three decades, the index has averaged a 0.8% decline in September.