According to Reuters, citing an SEC filing by Warren Buffett’s investment company, Berkshire Hathaway has added 4.3 million shares of Occidental Petroleum, boosting its total holding in the business to 19.2%.

The stock purchase is the most recent in a string of actions that have seen Berkshire Hathaway’s stake in Oxy rise from around 14% to about 20%. This has sparked speculation that the investment company may be preparing to acquire the major oil company. $10 billion in equity from Berkshire Hathaway was used to finance Oxy’s acquisition of Anadarko three years ago and the investment firm acquired the stock purchase warrants that would have allowed it to acquire 20% or more of Occidental as part of this agreement.

The purchase of Anadarko by Occidental for $55 billion in 2019 was one of the largest M&A transactions in the energy sector. It outbid Chevron, which had previously declared a bid for the oil company. Due to the imbalanced supply and demand in the oil markets and Russia’s war with Ukraine, which worsened the already dire supply situation, Occidental has seen its stock price double since the beginning of the year.

Buffett, though, is placing bets on multiple oil and gas horses. The wealthy investor started selling up his financial services interests earlier this year in favour of oil and gas companies like Oxy and Chevron.

In 2022, the energy sector has performed better than every other sector. Investors have started to show interest in companies that were formerly seen as pariahs due to their involvement in the oil and gas industry.