Warren Buffett's Berkshire Hathaway has actually been aggressively expanding its stake in Occidental Petroleum, making big buys over the past nine trading days.

R ecently a regulatory filing showed that its share of the oil and gas company has risen to near 29 percent, making it the biggest institutional investor in the company. Omaha-based conglomerate Berkshire Hathaway, through a series of almost daily purchases, began buying the shares on June 5 at nearly $60. It has purchased 7.3 million extra shares up to this point to drive its total holding above 255 million shares or as high as 28.8% of the company. The investment has thrust Occidental into the sixth-largest holding among Berkshire's enormous investment portfolio.

Berkshire has far more than just a common stock investment in Occidental. It also owns $10 billion of preferred stock, which makes for a rather rich financial tie between the two companies. It also has warrants for another 83.9 million common shares at the price of $59.62 per share issued as part of a deal in 2019, which helped finance Occidental's acquisition of Anadarko Petroleum.

With Occidental's shares having lately sold for $60.20, Berkshire can gain from these warrants by exercising them. If it exercised those warrants and the company thereafter cancelled all its preferred stock in Occidental, it could end up owning more than 40% of the firm.

All this notwithstanding, Buffett has nonetheless clarified that he does not intend to pursue full control of Occidental. Actually, despite Berkshire receiving regulatory approval to acquire up to 50% of the company's share capital and amid speculations as to the possibility of a takeover, Buffett seems focused on a long-term investment strategy rather than on trying to gain control of the company.