What happened 

Occidental Petroleum's (OXY 0.54%) stock price rose 4.8% on Tuesday after Warren Buffett-led Berkshire Hathaway (BRK.A -0.38%) (BRK.B -0.39%) boosted its stake in the oil and gas company. 

So what

Buffett's investment conglomerate bought more than 794,000 shares of Occidental Petroleum for roughly $55 per share on Thursday, according to a regulatory filing posted on Monday. The purchases brought Berkshire's holdings in the energy provider to over 153.5 million shares -- a stake valued at nearly $9.5 billion.

Now what 

Berkshire helped to finance Occidental's acquisition of Anadarko Petroleum back in 2019. In exchange for its $10 billion investment, Berkshire received preferred stock that yields 8% per year in dividend payments. It also received a warrant to buy as many as 80 million shares of Occidental at an exercise price of $62.50 a share.

Buffett began to ramp up Berkshire's position in Occidental in February. During an interview with CNBC, Buffett said he was pleased with what he heard from CEO Vicki Hollub in a transcript of the company's fourth-quarter earnings call. "I read every word and said this is exactly what I would be doing," Buffett said. "She's running the company the right way."

Occidental's shares have more than doubled so far in 2022, making it one of the best-performing stocks in the S&P 500 this year. The energy leader is benefiting from surging oil and gas prices. In turn, Occidental is using its bountiful free cash flow production to pay down the debt it took on to acquire Anadarko. It also intends to reward shareholders with stock buybacks and rising dividend payments.