Stocks surrendered early gains and turned negative on Wall Street after the White House said President Donald Trump would impose promised tariffs on some key U.S. trading partners.The S&P 500 fell 0.5% in Friday afternoon trading and the Nasdaq composite dropped 0.4%. Each had posted solid gains in morning trading. The Dow Jones Industrial Average was down 0.7%.Trump will put in place 25% tariffs on imports from Canada and Mexico and 10% tariffs on goods from China effective Saturday. The White House provided no word on whether there would be any exemptions to the measures that could result in swift price increases to U.S. consumers.The earlier gains on Wall Street had helped shave losses from the start of the week over worries that the artificial-intelligence boom may not require as much investment as thought. The S&P 500 is now on track for a weekly loss of 1%.Apple reversed course from market leading gains to a loss of 1.5%. The company earlier reported stronger profit for the latest quarter than analysts expected. Wall Street’s most valuable company, and thus the most influential on the S&P 500 and other indexes, said sales of its iPhone sales dipped. But revenue for its services businesses, such as AppleCare and its app store, rose to a record.KLA, a supplier to the electronics industry initially rose after reporting profit and revenue that topped analysts’ expectations, but then fell 0.8%. The company, which credited its results on expanding artificial-intelligence and high-performance computing investments, fell 6.3% on Monday. That’s when tech stocks around the world tumbled, after a Chinese upstart, DeepSeek, said it developed a large language model capable of competing with the world’s best, without having to use top-flight chips.The disruption raised questions about whether all the investment expected for AI chips, data centers and electricity is really needed.Shares of Nvidia, considered the poster child for the AI frenzy, fell 3.6%. They are down 15.7% for the week. Its CEO, Jensen Huang, is expected to meet with Trump Friday in Washington.U.S. stocks also got some help Friday from a relatively calm bond market, where rising Treasury yields had been cranking up the pressure in recent months.Treasury yields held relatively steady after an update on the measure of inflation that the Federal Reserve prefers to use came in almost exactly as economists expected. The yield on the 10-year Treasury rose to 4.58% from 4.52% late Thursday.Yields have been generally climbing since September as the U.S. economy has remained much more solid than economists expected. More recently, worries about tariffs and other possible policies coming from President Donald Trump that could add upward pressure on inflation and the U.S. government’s debt have also sent yields higher.The Fed left its benchmark interest rate unchanged as it closed out its most recent meeting Wednesday. The central bank is signaling a more cautious approach as