In late 2016, Warren Buffett started what would become the most profitable investment in his legendary career. Through his company, Berkshire Hathaway Corp. (BRK.A), he began accumulating shares in Apple Inc.

At Berkshire Hathaway’s annual meeting earlier this year, Warren Buffett showed just how much of a fan he is of Apple’s CEO, Tim Cook. “Tim Cook has made Berkshire a lot more than I have made Berkshire,” Buffett said to laughter in the room. It was funny, but considering that Apple is Berkshire’s largest holding, I don’t think it was hyperbole.

Warren Buffett is the world’s most famous investor and is renowned for his sober, long-term approach to the substantial equity stakes he takes in companies. One of his best-known sayings about Berkshire Hathaway is,

Warren Buffett's $66 billion stake in Apple just got a boost from their $100 billion U.S. investment. He's laughing at hedge funds and winning geopolitics.

Also notice that although these are six brand-new positions, they add up to about $4 billion, significantly less than the proceeds from the Apple, Bank of America, and T-Mobile sales, which is how Berkshire was still a net seller of stocks for the quarter.

Warren Buffett's Berkshire Hathaway built a $1.6 billion stake in UnitedHealth last quarter, marking one of its last wagers with the investor as CEO.

Billionaire investor Warren Buffett is known for his emphasis on long-term investments. He focuses on businesses that he believes will maintain a competitive edge for decades to come. What Happened: Buffett’s “buy and hold” strategy is the key to his advice for Apple investors to not get caught up in short-term metrics.