Open this photo in gallery: A trader works on the floor of the New York Stock Exchange in New York City on July 26.BRENDAN MCDERMID/Reuters If you’re not confused by this topsy-turvy stock market, you should be. Global stocks have defied expectations this year, roaring higher despite a massive surge in interest rates and widespread predictions of an imminent recession. Yet the big gains also seem surprisingly fragile. They have been driven, in large part, by huge advances in a handful of big U.S. tech companies that are expected to benefit from AI. Outside that charmed circle, earnings growth is...