Warren Buffett Sells Exxon, Buys Iron Mountain

Warren Buffett did some fine-tuning on his investment portfolio in the fourth quarter and changed direction on one of his oil investments, on a portfolio which rose about 2.4% in value during the quarter, to about $57.9 billion at Dec. 31.

Following investment moves he had begun in earlier quarters, Mr. Buffett continued reducing his stake in ConocoPhillips Co., an investment he has called a mistake. This time he shaved almost 20 million shares, to 37.7 million shares at the end of December from the end of the third quarter.

Mr. Buffett's investment vehicle, Berkshire Hathaway Inc., reported its investments in common stock in a regulatory filing Tuesday.

Mr. Buffett also reversed direction on his holdings of Exxon Mobil Corp., cutting his stake to 421,800 shares at December 31 from the 1.23 million he reported at the end of September. Mr. Buffett reported that he had first owned shares of Exxon Mobil as of June 30. Click here