For its part, Buffett said Berkshire is sitting on $116 billion of low-yielding cash and government bonds - whose average maturity was 88 days as of year-end 2017.
The rest was a gift from the new US tax code.
"Upon the enactment of the [Tax Cuts and Jobs Act of 2017], we recorded a reduction in our deferred income tax liabilities of approximately $35.6 billion for the effect of the aforementioned change in the USA statutory income tax rate.
Over time, however, Ben Graham's oft-quoted maxim proves true: 'In the short run the market is a voting machine; in the long run, however, it becomes a weighing machine, '" Buffett wrote in his newest annual shareholder letter.
The billionaire and CEO of Berkshire Hathaway highlighted a $29 billion tax gain for his company, bemoaned a lack of good deals and reminded his readers that owning stocks through low-priced index funds was the best way to build wealth over time.
"Prices for decent, but far from spectacular, businesses hit an all-time high", he said.
In January, Buffett, 87, narrowed down the list of people who could replace him to two veteran Berkshire executives, Greg Abel and Ajit Jain. The compounded annual return over the last 53 years is 19.1%.
Book value per Class A share, which reflects assets minus liabilities and which Buffett considers a good yardstick for Berkshire's intrinsic worth, also benefited from the tax cut, rising 13 percent in the fourth quarter to $211,750.
Treasury yields have been rising since the start of the year, stemming from brewing inflationary pressures and massive bond supply to help fund US President Donald Trump's tax overhaul.
"We expect Buffett's annual letter to reassure investors that his health remains remarkable and he intends to be around for awhile", said Cathy Seifert, equity analyst at CFRA Research in NY.
Buffett urged investors to stick with stocks even though they can be riskier in the short-term.
Buffett says using borrowed cash to buy stocks, or "buying on margin", is a no-no for individual investors. That ended a year ago, and Buffett - who bet slow, steady gains by the S^and^P 500 would beat out hedge funds over the decade - won with flying colors.