Berkshire Hathaway’s latest 13F regulatory filing reveals quite a sizeable stake in Exxon Mobil Corporation (NYSE:XOM) taken during the September quarter. Warren Buffett’s firm also increased its position in DaVita HealthCare Partners Inc (NYSE:DVA) and sold millions of shares of ConocoPhillips (NYSE:COP).

Berkshire Hathaway

During the third quarter, Berkshire Hathaway reduced its position in four companies, bought just one new stock and added to its position in five companies. Wells Fargo & Co. (NYSE:WFC) makes up 20% of the firm’s portfolio and is its biggest holding. The bank is followed by The Coca-Cola Company (NYSE:KO), which makes up more than 16% of Berkshire’s portfolio. The other companies in the firm’s top five holdings are International Business Machines Corp. (NYSE:IBM), American Express Company (NYSE:AXP) and The Procter & Gamble Company (NYSE:PG).

Berkshire Hathaway’s new stake in Exxon Mobil

The firm snapped up almost 40.1 million shares of Exxon Mobil Corporation (NYSE:XOM) during the September quarter. CNBC estimates that the purchase makes Warren Buffett’s firm the sixth largest shareholder of the energy company. At today’s closing share prices, the firm’s stake was worth $3.74 billion.

According to CNBC, Berkshire hasn’t held any shares of Exxon Mobile Corporation (NYSE:XOM) since late 2011 when the firm sold its fairly small stake of around 420,000 shares. Because of how big this new position in the energy company is, CNBC reports that it means Warren Buffett himself made the decision to do it rather than one of its two portfolio managers.

Position increases

The firm also added almost 1.5 million shares of DaVita HealthCare Partners Inc (NYSE:DVA) during the quarter. Other position increases from Berkshire Hathaway during the September quarter include Suncor Energy Inc. (NYSE:SU), U.S. Bancorp (NYSE:USB), Verisign, Inc. (NASDAQ:VRSN) and The Bank of New York Mellon Corporation (NYSE:BK).

Berkshire Hathaway’s exits and position reductions

During the September quarter, Berkshire Hathaway did not exit any positions, but it did slash some of its current ones. The firm sold more than 1.1 million shares of GlaxoSmithKline plc (ADR) (NYSE:GSK) and almost 10.6 million shares of ConocoPhillips (NYSE:COP).

Berkshire Hathaway also cut its positions in DIRECTV (NASDAQ:DTV) and Sanofi SA (ADR) (NYSE:SNY).