Apple CEO Tim Cook holds an iPhone 17 Pro and an iPhone Air as Apple holds an event at the Steve Jobs Theater on its campus in Cupertino, California, United States, on September 9, 2025.

Manuel Orbegozo | Reuters

Apple announced Monday that CEO Tim Cook will be replaced by John Ternus. Executives across the tech industry and beyond began reacting to the transition shortly after the news broke.

Cook served as CEO of the iPhone maker for nearly 15 years after late founder Steve Jobs stepped down in 2011.

President Donald Trump praised Cook’s tenure in a Truth Social post early Tuesday, saying, “It started with a phone call from Tim at the start of my first term.”

“Tim Cook has had an AMAZING career, almost unparalleled, and he will continue to do great work for Apple and whatever else he works on. Quite simply, Tim Cook is an incredible guy!!!” Trump wrote.

Trump continued to praise Cook’s work on CNBC’s “Squawk Box” Tuesday morning.

“I got to know him very well,” Trump said. “He’s a fantastic person, he did an incredible job.”

“Tim Cook is a legend,” OpenAI CEO Sam Altman wrote on X. “I am very grateful for everything he has done, and I am very grateful for Apple.”

Apple and OpenAI first partnered in 2024, integrating ChatGPT into Siri and Apple’s writing tools.

Oculus VR founder Palmer Luckey also posted on X and wrote, “RIP Tim Apple,” referencing the famous Trump White House incident in 2019.

During his first term, Trump incorrectly addressed Cook as “Tim Apple.” Cook made light of the comment and replaced his last name with the Apple logo on his Twitter profile.

Luckey left Facebook in 2017 and founded defense company Anduril later that year.

Berkshire Hathaway Chairman Warren Buffett told CNBC’s Becky Quick, “Without Tim Cook, Apple wouldn’t be the Apple it is today.”

“What he did with Apple was something no one I know could do,” Buffett said. Apple is Berkshire Hathaway’s largest holding.

“He covers the world, deals with countries with diverse histories and acts well towards the customer, the people who have worked for him, most importantly the shareholders that we were fortunate to be one of…he is one of a kind,” Buffett said.

Ternus, currently senior vice president of hardware engineering, will become CEO effective September 1. Cook will then assume the role of Executive Chairman.

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