Shares of Berkshire Hathaway Inc. Cl B sank 0.33% to $405.77 Wednesday, on what proved to be an all-around mixed trading session for the stock market, with the S&P 500 Index rising 0.51% to 5,537.02 and the Dow Jones Industrial Average falling 0.

Few stocks have performed as well as Berkshire Hathaway ( BRK.A -0.29%) ( BRK.B -0.40%). Since 1965, shares have increased in value by nearly 4,000,000%! A $10,000 investment would now be worth more than $350 million.

Warren Buffett's Berkshire Hathaway BRK owns 50 million shares of Kroger KR stock, which is roughly 6.9% of the company. And while it's a large percentage of Kroger, it only represents approximately 0.6% of Berkshire's portfolio.