Feb. 15 (Bloomberg) -- Billionaire Warren Buffett's Berkshire Hathaway Inc. became the largest shareholder in Kraft Foods Inc., the world's second-biggest foodmaker.

Berkshire owned 132.4 million shares, or about 8.6 percent of Northfield, Illinois-based Kraft, according to a regulatory filing yesterday that updated the company's holdings as of Dec. 31. Kraft, the purveyor of Nabisco crackers and Maxwell House coffee, has been independent since March, when Altria Group Inc. spun off its majority interest.

``Kraft's a portfolio of iconic brands in a company that was undermanaged for quite a long time,'' said Tom Russo, who helps manage $3 billion, including shares of Berkshire and Kraft, at Gardner Russo & Gardner in Lancaster, Pennsylvania. ``The brands have the ability to carry the returns, once they're properly managed, which you're seeing under way now.''

Buffett, the second-richest man in the U.S., is often mimicked by investors who follow his stock picks. Using that strategy for the past 31 years would have delivered annual returns of about 25 percent, double the return of the Standard & Poor's 500 Index, according to an academic study. The index declined 3.8 percent in the fourth quarter.

Berkshire, based in Omaha, Nebraska, also disclosed a stake in drugmaker GlaxoSmithKline Plc, with 1.51 million American depositary receipts. The company increased holdings in Wells Fargo & Co., the nation's