Tim Cook’s departure as chief executive officer of Apple marks the end of one of the most successful corporate leadership tenures in modern business history. Cook formally stepped down as CEO on September 1, 2026, handing control of the company to longtime Apple hardware executive John Ternus.

Cook has now become executive chairman of Apple’s board, where he is expected to remain involved in major strategic issues and relations with governments around the world. Cook became Apple’s CEO on August 24, 2011, succeeding company co-founder Steve Jobs, and he led Apple for fifteen years.

Tim Cook helped Apple expand its product suite beyond its popular iPhone, and in so doing transformed the landscape of personal electronic devices. During his leadership, Apple introduced the Apple Watch, AirPods and Vision Pro while expanding services such as Apple Music, Apple TV, Apple Pay and iCloud. Apple’s services eventually became a business generating more than $100 billion annually.

The company also shifted Macs to Apple-designed processors, giving Apple greater control over the technology underlying its computers. Its worldwide installed base grew to more than 2.5 billion active devices. When Cook took control, there were questions about whether anyone could successfully follow Jobs, whose personality and product vision had become nearly synonymous with Apple.

Cook ultimately built a different kind of legacy, emphasizing operational efficiency, supply-chain management, global expansion and the creation of an interconnected ecosystem of hardware and services. Apple’s market capitalization was roughly $350 billion when Cook became CEO.

By the time his departure was announced, Apple said its value had reached approximately $4 trillion, while Reuters reported the company was worth about $4.5 trillion by the end of his tenure. Annual revenue climbed from approximately $108 billion in fiscal 2011 to more than $416 billion in fiscal 2025.

Mr. Cook left behind challenges as well. Apple has faced criticism for moving more slowly than rivals such as Google, Microsoft and OpenAI in artificial intelligence. The canceled Apple automobile project and relatively limited adoption of the Vision Pro headset also raised questions about whether Apple could continue creating entirely new product categories.

Those challenges now belong to Apple’s new CEO, John Ternus. Ternus joined Apple’s product-design organization in 2001 and became vice president of Hardware Engineering in 2013 before joining Apple’s executive team as senior vice president of Hardware Engineering in 2021.

A mechanical-engineering graduate of the University of Pennsylvania, he helped oversee development of products including the iPad, AirPods, iPhone, Mac and Apple Watch and played an important role in Apple’s transition to its own silicon processors.

Ternus is expected to preserve Apple’s traditional emphasis on carefully engineered hardware while accelerating the company’s efforts in artificial intelligence. One of his central challenges will be making AI a deeper part of the iPhone, Mac and Apple services ecosystem while managing a complicated global supply chain and reducing Apple’s dependence on Chinese manufacturing.

Cook transformed Apple from an enormously successful technology company into a global economic giant. Ternus inherits that strength, but his success will depend on whether Apple can again demonstrate that it can lead the transition to AI.