Warren Buffett’s Berkshire Hathaway added to its already large Occidental Petroleum stake over the past trading sessions, a regulatory filing revealed Tuesday evening.

The Omaha-based conglomerate bought nearly 5.8 million shares of the oil company in a few separate trades on Friday, Monday and Tuesday, paying prices in the range from $59.8 to $61.9, the filing showed.

The latest purchase, totaling more than $350 million, marked the first time the “Oracle of Omaha” hiked his bet since September. Berkshire now owns 200.2 million shares of Occidental, worth $12.2 billion based on Tuesday’s close of $60.85.

Occidental, now among Berkshire’s top 10 holdings, saw its stock retreat about 3% this year following a stellar 2022. The energy name was the best performer last year, more than doubling in price.

On Monday, Occidental CEO Vicki Hollub said in an interview with CNBC’s Brian Sullivan that she met with the 92-year-old investor “just a few days ago.” Hollub said they talked about the oil and gas industry and the technology involved in it.

In August, Berkshire received regulatory approval to purchase up to 50%, spurring speculation that it may eventually buy all of Houston-based Occidental.

Berkshire also owns $10 billion of Occidental preferred stock, and has warrants to buy another 83.9 million common shares for $5 billion, or $59.62 each. The warrants were obtained as part of the company’s 2019 deal that helped finance Occidental’s purchase of Anadarko.