Buffett says Sokol investigation ongoing: report

Buffett also said Sokol had not been his designated successor. In an investor letter on Saturday, Buffett said Berkshire's board had identified the person who would succeed him as CEO; he said Monday that person had been the same for years now.

Sokol, one of Buffett's star lieutenants and long presumed to be his successor, left Berkshire last year amid questions of improper stock trading.

The episode prompted inquiries from securities regulators and was a black mark on Buffett's track record, but there was no mention at all in his summation of the year.

Buffett's comments on Saturday about the hunt for his successor helped to ease some shareholder concern about the future of the company once the famed 81-year-old investor steps down as chief executive.

While Buffett is in his 80s, he is known to be in good health and has made clear he does not plan to step down from running the company any time soon.

Buffett has been at the helm of Berkshire for 47 years. He controls a conglomerate that employs more than 270,000 people worldwide in dozens of businesses ranging from railroads and electric utilities to ice cream and underwear.

(Reporting By Ben Berkowitz, writing by Chris Kaufman)