Tim Cook will step down as Apple’s chief executive on Sept. 1. Cook, who took over from Steve Jobs in 2011, led the company for about 15 years and grew Apple’s corporate value from $350 billion to about $4 trillion, while expanding beyond the iPhone into wearables, payments, streaming and augmented reality. He cited the 2012 launch of Apple Maps as his biggest mistake and named the Apple Watch as his proudest achievement.

Apple is expanding its advertising business to offset slower hardware growth as iPhone replacement cycles lengthen. It plans to introduce ads in its Maps app this summer and launch Apple Business, a platform for businesses combining ad tools, Business Insider reported. Apple aims to widen its reach into the small and midsize business ad market. Omdia estimated Apple’s ad revenue rose 15 percent last year to about $7 billion.