S&P 500, Nasdaq end down on tech stocks, investors weigh Iran moves

STORY: Wall Street's main indexes ended mixed on Monday, with the Dow adding about a quarter of a percent, the S&P 500 shedding roughly the same amount, and the Nasdaq sliding around three-quarters of a percent. Investors braced for a busy week that includes Fed Chair Kevin Warsh's debut speech at the central bank's annual Jackson Hole symposium. Rob Haworth is senior investment strategy director at U.S. Bank Asset Management Group. "We've got a big week ahead of us with Nvidia earnings on Wednesday, personal income and PCE [Personal Consumption Expenditures] also on Wednesday. So that'll be key. And then none of us are really sure what Chair Warsh is going to say on Friday morning. It probably isn't a lot about the future of monetary policy, but we are all interested in, what is the reaction function going to be? And we're maybe hopeful that he'll say something. But I think this is a market that's kind of waiting for some direction, and there's maybe a little nerves ahead of all that.” :: Archive Meanwhile, the Trump administration announced a possible expansion of sanctions on countries doing business with Iran as part of what it billed as an "economic D-Day," but stopped short of actually imposing penalties. Chip stocks sold off, with Nvidia dropping 3%, Micron Technology falling nearly 6% and Broadcom sliding about 2.5%. Separately, President Trump warned that tariffs on cars, trucks and automotive parts from Canada would be increased to 50% starting January 1 after trade talks collapsed over the weekend. Shares of Ford and General Motors fell, while trucking company J.B. Hunt Transport tumbled nearly 6%.