Apple’s new CEO John Ternus takes the helm of the iconic tech giant on Tuesday, ending Tim Cook’s 15-year tenure that saw the company’s value skyrocket to $4.6 trillion thanks to the iPhone’s enormous popularity. The transition to a new CEO comes at a pivotal time for Apple. Artificial intelligence has unleashed the greatest upheaval within the industry since Jobs unveiled the first iPhone in 2007. Apple has gotten off to a rough start in AI after stumbling in its efforts to deliver new features built on the technology, as promised nearly two years ago.