The S&P 500 is up 11% year-to-date, fueled in-part by a frenzy over artificial intelligence that has also driven rallies in stock markets the world over. Earnings estimates have risen in tandem: Analysts tracked by Bloomberg Intelligence expect profit growth of 7.4% for US stocks in the third quarter, up nearly two basis points since mid-August. With trade tensions once again soaring and worries of a tech-fueled bubble percolating beneath the surface, Corporate America will need to deliver strong results to justify the nearly 32% gain the S&P 500 has notched from its April low.