"What he has done with Apple could not be done by anybody I've known.""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," he added.Apple is Berkshire Hathaway's largest shareholding.Ben Bajarin, CEO at Creative StrategiesBen Bajarin, CEO at consumer tech research firm Creative Strategies, said Cook will get a lot of credit for helping Apple scale, but that "an equally important part of his legacy is cultural.""His job was not only to grow Apple after Steve Jobs," he wrote on X. "It was to preserve as much of Apple's core identity, values, and operating culture as possible while leading it through a vastly different era."Palmer Luckey, cofounder of Anduril and Oculus VRPalmer Luckey.Bloomberg/Getty ImagesPalmer Luckey posted on X: "RIP Tim Apple."The nickname refers to a 2019 incident when President Donald Trump mistakenly called Cook "Tim Apple."

Then, on Twitter, Cook temporarily changed his last name to the Apple logo, and the sobriquet has become a lasting lighthearted reference.Dan Ives, managing director at Wedbush Securities"These will be big shoes to fill and the timing of Cook exiting stage left as CEO could make sense but also creates questions," the tech analyst said in an X post."Apple is making a major transition on its AI strategy and longtime CEO and legendary Cook leaving now is a surprise," he added. "We agree with Ternus as the pick."Patrick Moorhead, CEO of Moor Insights & StrategyMoorhead said Ternus is a continuity candidate.Errich Petersen/SXSW Conference & Festivals via Getty ImagesPatrick Moorhead, the CEO of Texas-based analytics firm Moor Insights & Strategy, said in an interview with CNBC that Ternus is a "continuity candidate" and not a "risk-taking visionary.""What I'm expecting and what the streets should expect is tight operational execution, margin management, and incremental product iteration," Moorhead said.He added, "I think that's what the institutional side of the house really wants, as opposed to swinging around the room AI features, which up to this point, the company hasn't needed at all."Andrés Avila Páez, cofounder of Arturito AIAndrés Avila Páez, cofounder of Arturito AI, said in a post on X, translated from Spanish, that Cook's legacy was one of "pure operational engineering.""Steve Jobs had the idea and created the iPhone. Tim Cook imagined and designed something even more difficult: the machine that manufactures it 200 million times a year without failing," he said.Robert Reich, former US Secretary of LaborRobert Reich was more critical of Cook.Win McNamee/Getty ImagesRobert Reich, professor at UC Berkeley and former US Secretary of Labor, took a more critical view of the resignation, urging people to remember Cook's $1 million contribution to Trump's inauguration."He fawned over Trump and gifted him a 24-karat gold plaque (as Apple lobbied for tariff exemptions)," Reich wrote on X of Cook.Joseph Carlson, founder of QualtrimJoseph Carlson, founder of Qualtrim and host of The Joseph Carlson Show on YouTube, defended Cook against critics who proclaim "Tim Cook didn't innovate!"In a post on X, he listed products created at Apple while Cook was CEO, including the Apple Watch, AirPods, Apple TV, Apple Pay, Face ID, and more."Don't come at me with this idiotic take that Tim Cook's Apple didn't innovate," he wrote.Anthony Pompliano, CEO of Professional Capital ManagementAnthony Pompliano.Bloomberg