In 2012, Buffett disclosed that he had been diagnosed with prostate cancer. He began undergoing radiation treatment in July, and successfully completed his treatment in November. The health scare did little to slow the octogenarian, who annually ranks near the top of the Forbes world billionaires list. In February 2013, Buffett purchased H. J. Heinz with private equity group 3G Capital for $28 billion. Later additions to the Berkshire Hathaway stable included battery maker Duracell and Kraft Foods Group, which merged with Heinz in 2015 to form the third-largest food and beverage company in North America.