In a statement, Buffett said the 96-year-old Murphy phoned him on Monday and said his recovery "convinced him that he would feel more comfortable ending his activities at Berkshire. I accepted his wish. He will continue as a major shareholder and friend."

Murphy had been a Berkshire director since 2003.

His departure followed the 2020 exit from the board of Bill Gates, another friend of Buffett's and co-founder of Microsoft Corp, after 16 years of service. Another director, Walter Scott, died in September.

Gates was replaced by Ken Chenault, the former chief executive of American Express Co, a large Berkshire investment.

In 2021, Berkshire added Buffett's daughter Susan Buffett and fund manager Christopher Davis, the chairman of Davis Select Advisors, to its board.

Berkshire did not immediately name a replacement for Murphy. Three other Berkshire directors are in their 90s: Buffett, Berkshire vice chairman Charlie Munger, and businessman David "Sandy" Gottesman.

"Tom Murphy has taught me more about running a business than any other person," Buffett said. "We have been friends and mental partners for more than 50 years. My only regret is that I didn't meet him earlier."

(Reporting by Jonathan Stempel in New York; Editing by Chris Reese)