U.S. futures and Asian shares have skidded as worries over President Donald Trump's nominee to be the next Federal Reserve chair amplified jitters over a possible bubble in the artificial intelligence boom. South Korea's exchange, which is heavily influenced by tech-related developments, briefly suspended trading as its benchmark Kospi dropped 5%. Oil prices fell more than $3.50 a barrel and gold and silver also extended losses after plunging on Friday. The S&P 500 dropped 0.4% Friday after Trump named Kevin Warsh as his nominee to replace Fed chair Jerome Powell. The Dow industrials lost 0.4%. The Nasdaq composite lost 0.9%.