Berkshire Hathaway (BRK.B 0.86%) (BRK.A 0.84%) Chairman and CEO Warren Buffett is arguably one of the best-known investors in the world. The so-called Oracle of Omaha held court this weekend as investors flocked to the company's annual shareholder meeting in Nebraska, one of the biggest events of its kind.

In advance of the Saturday event, Buffett turned heads late last week when he revealed in an interview that Berkshire Hathaway had purchased (AMZN -0.14%) shares for the first time, saying, "One of the fellows in the office that manages money ... bought some Amazon, so it will show up" in regulatory filings later this month. 

This announcement led to the inevitable questions on Saturday about whether Berkshire was abandoning its value-investing roots with its purchase of Amazon.

A closeup of Warren Buffett in a crowd.

Image source: The Motley Fool.

How does Amazon fit into value investing?

As he suggested, Buffett didn't initiate the purchase. It came from one of his top lieutenants, Todd Combs or Ted Weschler, who handle independent portfolios with Buffett's blessing. When asked about the departure from Berkshire's value-investing foundation, Buffett dismissed the notion. "The people making the decision on Amazon are absolutely [as] much value investors as I was when I was looking around for all these things selling below working capital years ago," Buffett said. "That has not changed."  

He went on to compare the purchasing decision to buying any "cheap" stock. "The considerations are identical when you buy Amazon versus ... say, a bank stock that looks cheap against book value or earnings of some sort," he said. 

He pointed out that a host of financial metrics undergo review before Berkshire invests in any company, including sales, margin, and tangible assets, as well as the company's cash and debt positions.

"All those things go into making a calculation as to whether they should buy A versus B versus C, and they are absolutely following the principle," Buffett said of his lieutenants. He also pointed out that he didn't need to look over the shoulders of his money managers. "I don't second-guess them," he said. 

This isn't the first time Buffett has answered questions about Amazon. Back in 2017, when asked about why he hadn't understood Amazon's potential, Buffett said it was "stupidity." Here's more of what he had to say at the time:

I was impressed by Jeff Bezos early. I never thought he'd pull off what he did, on the scale of what's happened. It's changed your behavior, everybody's behaviors. The remarkable thing is he's done it in [e-commerce and cloud computing] at the same time that really don't have that much connection. 

Better late than never?

Both Buffett and Berkshire Vice Chairman Charlie Munger have admitted to missing the boat on some of the world's most successful tech companies, an area the Oracle of Omaha has long said was out of his area of expertise.

Munger on Saturday said he didn't feel he missed out on Amazon, noting that it would have been hard to predict that Bezos would be a "miracle worker." He did say, however, that he felt silly for not seeing the massive potential of search giant Google, a subsidiary of Alphabet (GOOGL -0.03%) (GOOG 0.04%).

"We screwed up," he said. 

Munger pointed out that both he and Buffett saw the results that the top-notch search engine optimization produced for Berkshire-owned Geico, and rather than taking the plunge, "we just sat there sucking our thumbs," he admitted. "We're ashamed." 

A rose by any other name

While Buffett didn't come right out and call Amazon a "value stock," the intention was clear. One of Buffett's top money managers ran the numbers and, based on his analysis, determined that Amazon was inexpensive compared with the criteria being used to measure the stock.

Buffett also pointed out that investing itself is inherently a value-focused activity because shareholders are "putting out money now to get more later on." 

I guess that makes Amazon a value stock after all.