U.S. stocks ended lower Tuesday after a volatile session. The Philadelphia SE Semiconductor index tumbled 7.9%, much steeper than the S&P 500, which lost 1.44%. Six of 11 S&P 500 sectors managed gains—consumer staples rose 1.8%. The Nasdaq dropped 2.21%. The Dow edged down 0.09%. On the NYSE, losers beat winners by a narrow 1.31-to-1 margin. Trading focused on recalibrating AI capex. “Some of the news lately about AI raises questions about all the spending that’s being done and the capex and ramping of the capacity for semiconductors,” said Thomas Martin, senior portfolio manager at Globalt.