BOSTON ( TheStreet) -- Warren Buffett's Berkshire Hathaway ( BRK.B) is increasingly liking the prospects of MasterCard ( MA), as it doubled a stake in the credit card processor in the second quarter after first buying shares three months earlier.Berkshire Hathaway's 27-stock investment portfolio was valued at $52.4 billion June 30, down $1.2 billion, or 2.2%, in three months and about where it was at the start of the year, according to a filing Monday. The benchmark S&P 500 Index, in contrast, is down 5% this year.
Buffett initiated a small stake in the discount retail chain Dollar General ( DG), and now has a $51 million position. Dollar General would appear to be a bet that consumers will continue to pinch pennies -- or in this case dollars -- as the economy drags along as its goods appeal to low-income consumers. Dollar General's shares are up 3% this year and 9% over the past 12 months.