Buffett's Berkshire, hurt by Kraft Heinz, posts massive quarterly loss

Troubles at Kraft Heinz also cut deeply into the investing giant's bottom line. In his annual letter to investors posted Saturday, Buffett said the company took a $3 billion write down last year "arising almost entirely from our equity interest in Kraft Hein."

Overall, the investing giant was $4 billion in the black last year. And Buffett, who is famous for championing the importance of long-term performance, urged investors not to forget the forest for the trees.

"Investors who evaluate Berkshire sometimes obsess on the details of our many and diverse businesses -- our economic 'trees', so to speak."

Its overall portfolio was valued at $173 billion at the end of 2018.

Buffett said Berkshire does not see any potential takeover targets in the coming year — but the firm is hungry to make an "elephant-sized acquisition."

"Just writing about the possibility of a huge purchase has caused my pulse rate to soar," Buffett said.

Buffett also reiterated his criticism of accounting rules that he says over exaggerate Berkshire's performance by requiring the company to account for short-term stock fluctuations. Wild stock swings in December, the letter notes, had Berkshire recording "several days with a 'profit' or 'loss' of more than $4 billion.