Apple's stock surged over 15% in response to a 90-day pause on reciprocal tariffs announced by President Trump.This was the largest single-day gain for Apple since January 1998, when Steve Jobs served as interim CEO.The rally added over $400 billion to Apple's market cap, bringing it close to $3 trillion.The tariff pause raises the possibility of Apple serving a larger percentage of its U.S. customers from factories outside of China.