He also expressed his optimism for Berkshire. The company bought back a record of nearly $25 billion of its stock last year - signaling that investors have undervalued the conglomerate.

His businesses include auto insurer GEICO and the railroad BNSF, whose strong results helped lift quarterly operating income 14%. Gains in stocks like Apple drove the bottom line up 23%.

Curiously, Buffett did not specifically mention the pandemic in his letter even though it led to a loss of more than 31,000 jobs in Berkshire's workforce.

The health crisis also drained aerospace industry demand for parts, driving his company, Precision Castparts to cut more than 40% of its workers last year. Buffett admitted in the letter that he had overpaid when he shelled out $32 billion to buy it in 2016. He called that mistake "a big one."

He also disclosed that Berkshire will hold its annual shareholders meeting this year in Los Angeles - not in Omaha, where tens of thousands of people gather every year for what the "Oracle of Omaha" calls the "Woodstock for Capitalists."