(Bloomberg) — U.S. stocks tumbled and bonds soared after President Donald Trump said he is ending stimulus talks until after the election, just hours after Federal Reserve Chairman Jerome Powell renewed his warning that the economy will stumble without additional fiscal support.The benchmark S&P 500 slumped 1.4% after Trump tweeted his comments late in the trading session, erasing a gain of as much as 0.7%. The Dow Jones Industrial Average and Nasdaq Composite indexes also turned negative. Treasuries surged and the dollar jumped against most its major peers. An ETF that tracks the largest tech stocks fell an additional 0.6% in late trading after a House panel proposed a series of far-reaching antitrust reforms to curb the power of U.S. technology giants including Amazon.com Inc.and Alphabet Inc.“It was certainly a surprise to the market that had started to price in another stimulus,” Ed Clissold, chief U.S. equity strategist at Ned Davis Research, said in an interview on Bloomberg Television. “It’s going to be difficult for the economy to gain much traction until there is another round of stimulus.”House Speaker Nancy Pelosi had called on Republicans to get on board with a version of the stimulus bill the House passed last week with only Democratic votes. But significant gaps remained between the Democrats’ $2.2 trillion proposal and a $1.6 trillion offer backed by the White House.“Over the past few trading sessions the market had rallied around stimulus talks and now it’s almost a slap in the face,” said Gene Goldman, chief investment officer at Cetera Financial GroupThere are also lingering concerns about the trajectory of the pandemic and its effect on the economy. New York City’s seven-day average of daily cases is approaching Mayor Bill de Blasio’s warning threshold of 550. In France, the country’s statistics agency, downgraded its growth forecast to zero.Elsewhere, the pound weakened after a report that the European Union has no plans to offer concessions to Boris Johnson before next week’s Brexit deadline. Oil rose further after the biggest gain since May.Here are some key events coming up:On Wednesday, the minutes of the Sept. 15-16 meeting of the FOMC could be especially fruitful for Fed watchers, beginning with details of the debate on conditions necessary to trigger a rate increaseThe U.S. Vice Presidential debate takes place in Salt Lake City on WednesdayThough the final formal round of talks is over, the British government expects trade negotiations to continue up to the EU summit in mid-October.These are some of the main moves in markets:For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.