Berkshire Hathaway overpaid for part of venerable food giant Kraft Heinz and failed to realize the potential of Amazon.com, snapping up stock in the internet retailer only after it had already risen by thousands of percent.

That was the assessment by Warren Buffett and Charles Munger of two recent bets, leaving them in an unusual position this past weekend: Answering shareholder questions about whether changes are needed to an approach that has made them investing legends.

At Berkshire’s annual meeting in Omaha, Neb., holders filtered past the Kraft Heinz Co. booth featuring an inflatable ketchup bottle and a giant hot dog. The displays served as a reminder of a rough bet by Buffett, 88, and of questions about whether traditional consumer brands still carry weight in the age of internet stocks including Amazon, Berkshire’s latest investment.

Investors wanted to know how Berkshire’s businesses are working to stave off the risk that the world is changing faster than the conglomerate can react. For some, the questions about strategy reminded them of the days before the dot-com bubble burst or the financial crisis occurred.

“They’ve stayed relevant through lots of upheaval in their careers,” said Richard Cook, who oversees $335 million including Berkshire shares at Cook & Bynum Capital Management. “He’s nimble enough and now understands that a lot of those brands have been overstretched and now are no longer as durable as they were.”

Buffett has long searched for businesses with “moats,” or a long-term competitive advantage. Facing questions on new technology and Amazon, the billionaire investor acknowledged the shifting trends and said his managers were tasked with making sure they’re staying ahead.

“The world is going to change in dramatic ways,” said Buffett, Berkshire’s chairman and chief executive. “Just think how much it changed in the 54 years that we’ve had Berkshire — and some of those changes hurt us,” he quesZsaid, citing the namesake textile business and some shoe operations.

“But we do adjust and we’ve got a group, overall, of very good businesses,” Buffett said. “We’ve got some that will be actually destroyed by what happens in this world, but I still am a card-carrying capitalist and I believe that that’s a good thing.”

Kraft Heinz has been a headache for Berkshire. The food maker in February reported a $15.4 billion write-down and disclosed a subpoena from the Securities and Exchange Commission. Berkshire, which reported first-quarter results Saturday, couldn’t include results from Kraft Heinz, which is late publishing certain filings. Kraft Heinz on Monday announced it would restate some earnings and found evidence of employee misconduct in procurement.

An investment in Jeff Bezos’ online retailer was announced days ago by Buffett, who said it was the idea of one of his investing deputies, Todd Combs or Ted Weschler. Shareholders on Saturday asked about buying tech shares that had already exploded in price years ago, and whether that marks a change in Buffett’s well-known preference for value investing.

Buffett said technology firms can be evaluated on a basis similar to other stocks.