Warren Buffett's Berkshire Hathaway Inc has bought another 5.9 million shares of Occidental Petroleum Corp, boosting its stake in the oil company to about 15.2%.

The purchases were made on Monday and Tuesday and cost about $336 million, Berkshire said in a regulatory filing on Wednesday night.

Following the purchases, Berkshire owned about 142.3 million Occidental shares worth approximately $8.8 billion, plus $10 billion of preferred stock it acquired in 2019 to help finance Occidental's purchase of Anadarko Petroleum Corp.

Berkshire also has warrants to buy an additional $5 billion of Occidental shares at a slight discount to their Wednesday closing price of $61.57.

Occidental's share price has more than doubled this year, benefiting from Berkshire's purchases and rising oil prices, which got a further boost after Russia's invasion of Ukraine.

Berkshire has been on a spending spree in 2022.

It spent $51.1 billion on equities in the first quarter, including by increasing its stake in oil company Chevron Corp to $25.9 billion.

Berkshire has also this year announced large investments in video game maker Activision Blizzard Inc and computer and printer maker HP Inc, and a planned $11.6 billion purchase of insurance company Alleghany Corp.

(Reporting by Jonathan Stempel in New York; Additional reporting by Shubham Kalia in Bengaluru; Editing by Kim Coghill)