"If you look at Apple, I think it earns almost twice as much as the second most profitable company in the United States."
Buffett also criticised analysts and investors who have zeroed in on Apple's sales of the iPhone X.
Months earlier, many grew increasingly concerned that Apple's top-of-the-line phone has been a dud among consumers, due to its hefty US$1,000 price tag.
"The idea that you're going to spend loads of time trying to guess how many iPhone Xs are going to be sold in a given 3 month period totally misses the point," Buffett said.
"It's like worrying about the number of Blackberrys ten years ago."
Apple's stock price was also helped by the firm's better-than-expected results for the March quarter.
The firm said it sold 52.2 million iPhones in the last three months, which was in line with analysts' expectations.
Apple said that customers chose the US$999 iPhone X "more than any other iPhone each week" during the March quarter like they did in the December quarter.
The results propelled shares of Apple to experience six straight days of gains.
Apple is now just US$16 per share short of reaching the much-anticipated US$1t mark.
If it crosses the trillion-dollar threshold, it will become the first US company to do so - a title that fellow tech giants Amazon, Google and Microsoft have also been vying to achieve.
However, Apple currently remains far ahead of its rivals in terms of market cap, with Amazon trailing it at a valuation of US$773b.
Apple's market cap briefly rose above US$925b in March, before settling lower due to recent iPhone X concerns.
That's in contrast to last November, when there was talk that Apple could cross the US$1t threshold due to optimism around the 10th anniversary iPhone.
Now, many have begun looking ahead to upcoming iPhone releases in September as additional propellants for the stock.
Speculation has been building that Apple is slated to release a 6.1-inch iPhone next year that serves as a follow up to the 10th anniversary iPhone X.
The second-generation iPhone X would feature an even bigger screen, yet it may have a cheaper price point at just US$550 vs. the US$999 iPhone X.
A 6.1-inch screen would be the firm's largest iPhone yet.
Wall Street analysts expect Apple's stock price to surge 11 per cent and reach US$195 within the next 12 months, propelling its market cap to US$989b, according to Thomson Reuters data.
