Tim Cook reactions: Trump, Altman, Buffett and more on the Apple CEO move

Apple announced on 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 has served as the iPhone maker's CEO for nearly 15 years, after late founder Steve Jobs resigned in 2011.

President Donald Trump praised Cook's tenure in a Truth Social post early Tuesday, saying "it began with a phone call from Tim at the beginning of my First Term."

"Tim Cook had an AMAZING career, almost incomparable, and will go on and continue to do great work for Apple, and whatever else he chooses to work on. Quite simply, Tim Cook is an incredible guy!!!" Trump wrote.

Trump continued to praise Cook's work Tuesday morning on CNBC's "Squawk Box."

"I got to know him very well," Trump said. "He's a fantastic person, did an unbelievable job."

"Tim Cook is a legend," OpenAI CEO Sam Altman posted on X. "I am very thankful for everything he has done and I am very thankful for Apple."

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

Palmer Luckey, founder of Oculus VR, also posted on X, writing "RIP Tim Apple," referring to the famous White House incident with Trump in 2019.

Trump mistakenly addressed Cook as "Tim Apple" during his first term. Cook made light of the remark, replacing his last name with the Apple logo on his Twitter profile.

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

Warren Buffett, chairman of Berkshire Hathaway, told CNBC's Becky Quick that "Apple would not be the Apple of today without Tim Cook."

"What he has done with Apple could not be done by anybody I've known," Buffett said. Apple is Berkshire Hathaway's largest shareholding.

"Covering the world and getting along with countries with all kinds of histories and doing right by the customer, people who worked for him, certainly the shareholders, which we were lucky enough to be one of... he's one of a kind," Buffett said.

Ternus, currently a senior vice president of hardware engineering, will become CEO effective Sept. 1. Cook will then assume the role of executive chairman.