U.S. stocks were mixed as oil futures jumped in response to new attacks on Middle East energy shipments, volatility continued in bond markets and doubts surfaced about artificial-intelligence profits.

The Dow Jones Industrial Average rose 51.77 points, or 0.1%, to 51231.64. Meanwhile the S&P 500 fell 36.41 points, or 0.47%, to 7765.36, and the tech-heavy Nasdaq Composite slipped 345.35 points, or 1.25%, to 27193.34.

It was the latest turbulent session in a back-and-forth start to the fourth quarter for the U.S. stock market. In the tug of war between bears and bulls, each side is anchored by data. Bears can point to the surge in energy prices causing a lasting bout of higher inflation and interest rates. The bull case is frequently reinforced by statistics from the AI boom.

Oil futures surged $3.21, or 3.6%, to $91.49 a barrel after Iran struck a vessel near Qatar in an attack likely to slow tanker traffic in the Strait of Hormuz once again, while the approach of Hurricane Isaias threatened production in the U.S. Gulf.

Treasury yields fell after another well-subscribed auction, this time for 30-year bonds. That followed strong demand for a 10-year note auction Wednesday.

The yield on the 10-year Treasury note fell 0.049 percentage point to 5.232%. The yield on the 30-year bond declined 0.055 percentage point to 5.606%, the lowest close since Oct. 1 after testing multiyear highs earlier in the session. The yield on the two-year Treasury slipped 0.008 percentage point to 4.753%.