Warren Buffett did not have the best year in 2015. Berkshire Hathaway Inc. (NYSE: BRK.B) stock ended up down around 15% for the year. Buffett and his second in command, Charlie Munger, celebrated an important milestone in 2015, which marked 50 years since Buffett had taken over Berkshire. He grew it from a struggling textile mill to one of the largest companies in the world.

Many people in the financial community track the performance of Warren Buffett and his holdings. It makes sense that people want to see how one of the most successful investors of all time is performing. Still, as Buffett is a long-term investor, it makes more sense to judge Buffett on a long-term basis as opposed to just annually. Buffett made some substantial changes to the Berkshire Hathaway portfolio in 2015.

Wal-Mart Position Reduced

One change Buffett made to his portfolio was a reduction in the amount of stock owned in Wal-Mart Stores Inc. (NYSE: WMT). According to the 13F from the second quarter, Berkshire owned 60 million shares with a market value of $4.2 billion. This represented a 1.87% ownership interest in the company.

Berkshire sold 4.2 million shares, according to its 13F for the third quarter of 2015. The position had a market value of $3.63 billion. Wal-Mart’s stock dropped substantially in 2015. The retailer announced it was increasing the minimum wage it was paying its workers. Wal-Mart has a market cap of $203 billion with a dividend yield of 3.07% as of January 2016.

Phillips 66 Position Increase

Buffett increased his position in Phillips 66 (NYSE: PSX) substantially in 2015. Berkshire bought around 22.1 million shares in the second quarter of 2015. This position was increased further in the third quarter of 2015 to 61.4 million shares with a market value of $4.7 billion. This represents 3.71% of the total Berkshire portfolio. The shares comprise an 11.5% ownership interest in the company.

Buffett has been known to generally avoid stocks that have exposure to commodity prices, which makes the investment in Phillips 66 unusual. Buffett has been turning over some investment decisions to newly hired portfolio managers. These new managers could be behind the position.

Phillips 66 was a spin-off from ConocoPhillips in 2012. The company operates as an energy manufacturing and logistics company. It has less exposure to the retail price of crude oil than other energy companies. Crude oil prices continued to drop in the later part of 2015.

After sustaining a substantial rally up to $94 a share in November 2015, the stock was off the highs of 19% to around $76 a share. Phillips 66 has a market cap of $40 billion with a dividend yield of 2.94%. The entire energy sector continues to be weighed down by low crude oil and natural gas prices. Those prices need to rally substantially to see Berkshire’s investment in the company grow.

Increased Position in GM

Buffett also increased his position in General Motors Co. (NYSE: GM). Berkshire bought 9 million shares for a total of 50 million shares with a market value of $1.5 billion. The auto manufacturer has a market cap of $45.95 billion with a dividend yield of 4.7% as of January 2016.

GM has been the focus of a campaign by activist investor Harry Wilson. Wilson worked with the government to restructure GM after the 2009 bankruptcy. He has said GM should buy back its stock to the tune of around $8 billion. He also demanded a position on the board. Wilson said the company needs to maintain greater focus on its cash balance and operating performance. GM’s stock was volatile during 2015. It started the year around $35 a share, and then dropped to as low as $25 in late August before ending the year around $34.

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