Warren Buffett isn't shy about making big bets. Within Berkshire Hathaway's portfolio of publicly traded stocks, just 10 positions comprise more than 90% of its invested capital.

One of those positions is Occidental Petroleum (OXY 0.88%). Buffett and Berkshire are betting on this company in a far greater way than most investors realize.

Buffett and Berkshire are confident

According to the most recent filings, Berkshire's publicly traded portfolio is worth around $350 billion. It's important to note that this is just a piece of Berkshire's total asset base. It has, for example, complete ownership over dozens of additional businesses whose value is not included in this figure. Still, this $350 billion portfolio is a great way to see what Buffett and his investment team are backing.

Occidental Petroleum is currently the sixth largest position in this portfolio, just behind Chevron, another oil and gas producer. Berkshire owns around 250 million shares of Occidental Petroleum worth around $14 billion in total. Note that Occidental Petroleum has a market cap of around $60 billion, meaning Berkshire owns roughly one-quarter of the entire company.

Berkshire first bought shares in the first quarter of 2022. At the time, Occidental Petroleum shares traded between $20 and $30 per share. Today, the share price is above $60. Still, Berkshire remains heavily invested, with no share sales reported last quarter.

Occidental Petroleum and Chevron are the only oil and gas stocks Buffett owns in this portfolio, but in combination, they represent roughly 10% of the portfolio's total value. It's clear that someone at Berkshire, maybe even Buffett himself, loves Occidental Petroleum stock.