The U.S. stock market sank sharply in early trading, with investors increasingly skittish about the strength of the artificial intelligence boom.  The S&P 500, which set a record high in late October, fell 78 points, or 1.2%, to 6,594 roughly an hour into Tuesday's session. The Dow Jones Industrial Average and tech-heavy Nasdaq Composite dropped 1.2% and 1.6%, respectively.  The S&P 500 remains up more than 12% this year, the Dow has added 8% and the Nasdaq has risen more than 15%. AI pioneer