Warren Buffett's Berkshire Hathaway just piled another $350 million into Occidental stock - and now owns nearly 21% of the oil giant

• Warren Buffett's Berkshire Hathaway invested another $350 million in Occidental Petroleum stock.
• Buffett's company bought about 6 million shares, raising its stake to 194 million shares, or 20.8%.

Warren Buffett's Berkshire Hathaway has piled another $350 million into Occidental Petroleum over the past three days, a Securities and Exchange Commission filing on Wednesday showed.

The famed investor's conglomerate scooped up about 6 million shares at prices ranging from $57.67 to $61.60, boosting its total holding to 194 million shares. It now commands a 20.8% stake in the oil-and-gas company, valued at nearly $12 billion as of Wednesday's close.

Buffett and his team, who last added to their Occidental position on August 8, likely resumed buying this week because they saw the energy stock as a bargain once again. It has tumbled over 20% in the past month, from a nearly four-year intraday high of $77 on August 29, to $61 at last check.

Berkshire started buying Occidental shares on February 28, and grew its stake from scratch to 136 million shares, or more than 14% of the company, by March 16. It has built its entire position in the space of 35 trading days this year, a Markets Insider analysis of SEC filings shows.

Occidental CEO Vicki Hollub has said Buffett likes the fact her company is strong in the US, and that it is slashing its debts, reinstating its dividend, and buying back shares.

"We have multiple ways to return value to shareholders, and that's the kind of company that he likes," she recently told Fortune.

Buffett's clear interest in Occidental stock, and the fact he recently won regulatory approval to own up to 50% of the company, has stoked rumors that Berkshire might buy the company outright.

However, the investor famously spurns hostile takeovers, and he hasn't discussed a buyout with Occidental's bosses — making a takeover seem unlikely for the time being.

Berkshire has invested roughly $10 billion in Occidental this year, meaning it's made about $2 billion on paper to date. It also holds $10 billion of Occidental preferred stock, as well as warrants it can exercise to buy 83.9 million common shares at a fixed cost of $5 billion, which it received in exchange for financing the oil group's takeover of Anadarko Petroleum in 2019.