Berkshire Hathaway sees profit jump in 2015 amid BNSF revival

Warren Buffett
Adam Jeffery | CNBC

Berkshire Hathaway saw significant gains across its portfolio, the conglomerate said on Saturday in its annual letter to shareholders, a dispatch widely followed by the investing community.

The company owned and operated by Warren Buffett for more than five decades saw a jump in net worth during 2015 by $15.4 billion, Berkshire said, despite the conglomerate's share price having lagged the broad market recently.

Those gains boosted its per-share book value of both its Class A and Class B stock by 6.4 percent. For the full year, Berkshire earned $17.36 billion in operating profit, and $4.67 billion in the fourth quarter. Overall, Berkshire's profit increased to $24.08 billion over the year.

The Oracle of Omaha was also dismissive of the idea that the current state of the U.S. economy boded ill for the future. Buffett blasted what he called "a terrible mistake to bet against America," and stated that the current generation was "the luckiest in history."

Read MoreBuffett: Today's generation 'luckiest in history'

In its letter—a yearly ritual widely scrutinized by Wall Street for insight into Buffett's thinking and investment philosophy—Berskshire also said the performance of its railroad, BNSF, had improved "dramatically" after a troubled 2014.

"To attain that result, we invested about $5.8 billion during the year in capital expenditures, a sum far and away the record for any American railroad and nearly three times our annual depreciation charge," Berkshire wrote in its letter. "It was money well spent."

The railroad is part of Berkshire's "Powerhouse Five", a portfolio of the conglomerate's most profitable non-insurance companies. The five collectively earned $13.1 billion last year, a rise of $650 million from the comparable year-ago, Berkshire said. This year, the group will become the "Powerhouse Six", with the addition of Precision Castparts, which Berkshire recently bought for more than $32 billion.

Berkshire's "Big Four" stock investments include shares of American Express, IBM, Wells Fargo and Coca-Cola. The conglomerate increased its interest in all four during 2015. Some of those investments under-performed during the year, which were a drag on Berkshire's stock price.