Nvidia Corp. shares fell 3.5% on Tuesday, their steepest single-day decline since April 21, and closed below the stock’s 20-day moving average for the first time in almost four months. The pullback in the world’s most valuable chipmaker triggered a broader retreat in large-cap technology stocks that had underpinned this year’s equity rally. The sell-off pushed the Nasdaq 100 down 1.4%, marking its second-worst session since the April tariff shock and snapping a stretch of subdued summer trading. Despite gains in more than 350 members of the S&P 500, the reversal in a handful of megacaps underscored the market’s dependence on a narrow group of growth leaders. Away from equities, U.S. 10-year Treasury yields slipped three basis points to 4.30% as investors positioned for Federal Reserve Chair Jerome Powell’s speech at Jackson Hole on Friday, which could clarify prospects for a possible rate cut at the September meeting.