Following the outperformance of some of Berkshire Hathaway’s biggest holdings, Warren Buffett gobbled up 18 million more shares of Occidental Petroleum, in a deal worth almost $1 billion, reports an article in Forbes. That brings his total Occidental holdings to 136 million shares and a stake of almost 15% in the company, whose stock has soared over 80% in the wake of skyrocketing energy prices resulting from the war in Ukraine.

While Buffett’s biggest holding, Apple, which accounts for more than 40% of his portfolio in a stake worth $144 billion, is down roughly 10% and his biggest financial stock, Bank of America, is down about 3% this year, many of his other top holdings are outperforming. American Express shares are up 10%, and Kraft-Heinz is up 5%.

Buffett told CNBC in an interview quoted in the article that he was impressed with Occidental’s most recent earnings call and believes that its CEO Vicki Hollub is “running the company the right way.” Berkshire began purchasing shares late last month. Occidental isn’t the only energy company in Buffett’s holdings; he has a 2% stake in Chevron, which has also seen its shares shoot up 35% this year due to oil price spikes.

Berkshire Hathaway’s own shares are up 13% so far this year to near record highs. The company is valued at more than $750 billion and, the article contends, could well be on its way to becoming the next trillion-dollar company.