According to online reports, the latest documents show that Buffett's Berkshire Hathaway Company added US$28.55 million to purchase 143424 shares of Internet Infrastructure services company VeriSign in the three trading days ending on the 24th. Coupled with the stocks it has previously purchased, Berkshire currently holds a total of 13.7% of Verisign's issued shares, worth nearly $2.7 billion. Reported that one reason why Buffett is interested in Verisign may be that it ranks high in various profit margin indicators among companies in the Standard & Poor's 500 Index.