(Reuters) -A U.S. regulator has authorized Berkshire Hathaway Inc, the company controlled by billionaire Warren Buffett, to buy up to 50% of the common stock of oil company Occidental Petroleum Corp.

In an order made public on Friday, the Federal Energy Regulatory Commission (FERC) said that authorization was “consistent with the public interest.”

Occidental shares were up 6.6% at $69.16 in afternoon trading.

Neither Berkshire nor Occidental immediately responded to requests for comment.

Occidental’s share price has more than doubled this year, benefiting from rising oil prices following Russia’s Feb. 24 invasion of Ukraine.

Berkshire began buying Occidental shares around the time the invasion began, and by Aug. 8 had accumulated a 20.2% stake.

It sought FERC authorization for a maximum 50% stake on July 11, saying it would not hurt competition, undermine regulators’ authority, or cause consumers to pay more.

Berkshire also owns $10 billion of Occidental preferred stock, which helped finance the 2019 purchase of Anadarko Petroleum Corp, and has warrants to buy another 83.9 million common shares for $5 billion.

(Reporting by Jonathan Stempel in New York; Editing by Chris Reese and Jonathan Oatis)