(Reuters) -Alphabet's shares rose 5.5% in premarket trading on Monday after Berkshire Hathaway ( BRK/A ) disclosed a stake in the tech giant, marking what could be one of the final major moves by the conglomerate under the leadership of Warren Buffett.

A filing on Friday showed that Berkshire owned 17.85 million shares in Google's parent as of September 30. As of the stock's last close, the stake would be worth $4.93 billion, according to Reuters' calculations.

Berkshire's move comes amid growing concerns over Big Tech's heavy AI spending that intensified after Michael Burry, known for "The Big Short", deregistered his hedge fund last week following his recent criticism of leading AI companies.

Buffett is ending his 60-year run as chief executive officer of Berkshire Hathaway ( BRK/A ) at the end of 2025. He will be succeeded by Greg Abel.

It was unclear whether Buffett, his portfolio managers Todd Combs and Ted Weschler or Abel made the specific purchase, though Buffett typically oversees the larger investments.

At Berkshire's annual shareholder meeting in 2019, Buffett and late Vice Chairman Charlie Munger lamented not investing in Google sooner.

"We screwed up," Munger said.

Berkshire has traditionally steered clear of tech stocks, with Buffett arguing that Apple ( AAPL ), its largest stock holding, is a consumer-products company rather than a technology bet.

(Reporting by Niket Nishant in Bengaluru; Editing by Saumyadeb Chakrabarty)