The group, which is struggling to find where to invest these gains, also announced Saturday to have purchased a stock of $ 928 million (815 million euros) over the period July-September.
Operating profit doubled to $ 6.88 billion from $ 3.44 billion a year earlier, exceeding analysts' expectations of an average of $ 6.11 billion, according to I / B / E data / S of Refinitiv.
Insurance sales revenue was $ 441 million in the third quarter, compared with a loss of $ 1.4 billion a year ago.
"This is absolutely one of the biggest quarterly profits ever made by an American company," said Bill Smead, managing director of Berkshire shareholder Smead Capital Management.
Net income in the third quarter increased by more than 355% to $ 18.5 billion, due to a new accounting rule requiring the group to incorporate its unrealized capital gains.
Warren Buffett believes that this rule can mislead investors, which he urges to focus on operating income.
These results also reflect an effective Bershire tax rate of 19.2%, compared to 25.3% a year earlier, as a result of the tax reform passed in December by the US Congress.
Berkshire, based in Omaha, Nebraska, controls over 90 companies in insurance, chemicals, energy, agribusiness and retail, industry, rail and more.
The group is run on a day-to-day basis by Greg Abel and Ajit Jain, both considered potential successors to Warren Buffett as General Manager. Warren Buffett, 88, and his vice-president Charlie Munger, 94, decide together on large capital allocations.
Profits increased in each of its major divisions.
The book value of Class A, Warren Buffett's preferred performance indicator, was $ 228,712 in the third quarter, up from $ 217,677 in the second.
The Class A share ended Friday at 308,411.01 dollars on Wall Street, almost stable.
(Trevor Hunnicutt, Catherine Mallebay-Vacator for French Service)