Apple is closing in on a historic $4 trillion stock market valuation, powered by investors cheering progress in the company’s long-awaited AI enhancements to rejuvenate sluggish iPhone sales. The company has pulled ahead of Nvidia and Microsoft in the race to the monumental milestone, thanks to an about 16% jump in shares since early November that has added about $500 billion to its market capitalization. The latest rally in Apple shares reflects “investor enthusiasm for artificial intelligence and an expectation that it will result in a supercycle of iPhone upgrades,” said Tom Forte, an analyst at Maxim Group, who has a “hold” rating.