Berkshire Hathaway increases stake in Occidental Petroleum.

Berkshire Hathaway, owned by Warren Buffett, has increased its ownership stake in Occidental Petroleum to 23.6% by purchasing nearly 3.7 million additional shares for about $216 million. Berkshire has spent over $1 billion on the stock this month and now owns about 211.7 million Occidental shares worth $12.6 billion. Berkshire is Occidental's largest shareholder, and some analysts and investors have speculated that it might eventually buy the Houston-based company.