Warren Buffett's Berkshire Hathaway (NYSE: BRK-A) used the recent weaknesses in oil stocks, related to President Biden's attacks on the sector and recession worries, to add more Occidental Petroleum (NYSE: OXY) stock.

In an SEC Wednesday evening, Berkshire disclosed it bought another 9.55 million shares at prices from $54.96-$56.42 per share.

The value of the latest purchase was over $500 million.

The latest purchase brings the firm's stake to 152,713,846 shares. Berkshire also owns warrants that cover another 83,858,848 shares, with an exercise price of $59.62, and 100,000 preferred shares.

Shares of Occidental are down 21% since the start of June.