Berkshire Hathaway owns nearly 21% of Occidental Petroleum after a series of new stock purchases by chairman Warren Buffett.
According to a regulatory filing on Thursday, Buffett purchased additional 5.99 million shares in multiple transactions between Sept. 26 - 29. The stock was purchased at prices ranging from as low as $57.91 per share to as high as $61.37 per share.
Berkshire owns a total of 194.4 million Occidental shares for a stake worth of $11.9 billion.
Occidental saw its shares double this year as the company benefited from a rise in oil prices after Russia invaded Ukraine in February.
Berkshire Hathaway first bought into the Houston-based oil giant three years ago. The latest purchases came after Berkshire received regulatory approval to buy up to 50% of Occidental's common stock in August.
Berkshire holds warrants to buy additional 83.9 million Occidental shares at $59.62 apiece and owns $10 billion worth of preferred Occidental shares that pay an annual dividend of $800 million. It acquired both of them in 2019 when it helped finance Occidental's acquisition of Anadarko Petroleum.
The Occidental shares closed at $62.11 apiece at the end of Thursday's trading session. Shares have doubled year-to-date.
Buffett has also increased Berkshire's stake in Chevron, in addition to Occidental.
Berkshire owns more than 90 companies, including the BNSF railroad, Geico insurance, several major utilities and an eclectic assortment of other companies, including Dairy Queen, NetJets and Precision Castparts, in addition to its investments.