Warren Buffett says he'll never invest in Microsoft because of his billionaire bromance with Bill Gates

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Bill Gates and Warren Buffett

• Warren Buffett says that his decades-long relationship with Bill Gates is why Berkshire Hathaway will never buy Microsoft stock - it might create the illusion that Gates is leaking insider info.
• Gates and Buffett have been friends since 1991.
• While Buffett won't buy Microsoft, he just took a huge stake in Apple. But Gates was hugely supportive in an interview on CNBC, saying that Buffett made a smart choice.

Microsoft is on a roll: Thanks to the ongoing success of its cloud computing business, the tech titan's stock price has soared over 40% in the last year, making it a $733 billion company.

Yet, Warren Buffett, the legendary investor and "Oracle of Omaha," just said that not only does his firm Berkshire Hathaway not own any stake in Microsoft ... it never will.

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And it's all because of the 27-year billionaire bromance between Buffett and Microsoft cofounder Bill Gates.

"I try to stay away from a few things just totally because the inference would be drawn," said Buffett at the annual Berkshire Hathaway shareholders meeting, as reported by The Wall Street Journal.

In other words, Buffett won't let his firm buy up any Microsoft stock because it could create the illusion of wrongdoing. If Buffett's firm bought a huge stake in Microsoft - as it just did with Apple - and the stock pops on earnings or an acquisition, it might look like Gates had leaked some insider information to his old friend.

Still, Buffett and Gates weren't always close. Buffett chalked up the fact that he didn't buy any Microsoft before the two hit it off because of simple "stupidity," according to The Wall Street Journal.

Meanwhile, Gates seems hugely supportive of Buffett's big bet on Apple. Gates went on CNBC on Monday morning, and expressed his admiration of Apple.

"The top tech companies do have a very strong profit position right now but Apple has the most of all," Gates told CNBC.

This bizarre love triangle got weirder later on Monday, when Microsoft CEO Satya Nadella kicked off his keynote at the annual Microsoft Build conference. Nadella remarked that Monday marked the first time in 30 years he had ever heard Gates talk about the stock market - and it was in support of Apple.

"Today must be a new day for sure, when you hear Bill talk about Apple stock. That's the new Microsoft for you," joked Nadella.

Get the latest Microsoft stock price here.