Apple has named John Ternus as its new chief executive officer, effective September 1, while Tim Cook will transition to the role of executive chairman. The move ends Cook’s 15 year tenure leading the technology giant, a period marked by significant growth and product expansion.

Ternus, who joined Apple in 2001, has played a key role in the development of major products including the iPhone and AirPods. He said he is grateful for the opportunity to lead the company forward and continue its mission of creating innovative products and services.

During Cook’s leadership, Apple’s shares rose more than 1,700 percent, reflecting one of the most successful runs in modern corporate history. The leadership change marks the first transition at the top since Cook succeeded Steve Jobs in 2011, following years of updates to core products and ongoing efforts to strengthen the company’s position in emerging technologies such as artificial intelligence.