1. Occidental Petroleum Corp's (OXY) stock fell on Wednesday.
2. Berkshire Hathaway increased its stake in Occidental Petroleum to 24.9%.
3. Berkshire Hathaway purchased around $275 million of Occidental Petroleum stock recently.
4. The firm now owns 222 million shares worth $13 billion of Occidental Petroleum.
5. Berkshire Hathaway's stake increased following Russia's invasion of Ukraine which caused oil prices to surge.
6. Over $300 million of Occidental stock was purchased by Berkshire earlier in May.
7. On Tuesday, Berkshire accounted for over 15% of Occidental's stock volume by buying 2.2 million shares.
8. Warren Buffett previously denied reports of Berkshire taking control of Occidental.
9. OXY shares traded lower by 0.65% at $58.21 in premarket trading on Wednesday.