http://online.wsj.com/article/SB100...2188934674.html?mod=WSJ_Markets_section_Heard Betting On Berkshire's Index Bounce Trading in Berkshire Hathaway shares has become the subject of more intrigue this week than Warren Buffett's top-secret succession plan, which he reportedly keeps in an envelope in his office. Since Mr. Buffett's holding company split its Class B shares last month, adjusting their price down from more than $3,000 to $70, there has been a flurry of buying. A varied crowd has snapped up the stock, ranging from small investors following the Oracle of Omaha to professional traders hoping to game the stock's coming addition to the Standard & Poor's 500-stock index. In the B shares, trading volume surged from roughly an adjusted 30,000 shares a day in 2009 to 20 million on Jan. 27, the day after the S&P news was issued. It was 14 million Wednesday. Adding to the mix: Berkshire's purchase of railroad company Burlington Northern Santa Fe. As part of the deal, Burlington shareholders can choose between cash, Berkshire stock or a combination of both, creating further uncertainty around the flow of Berkshire trading. So, just minutes before the close of trading Tuesday, when someone sold a block of 4,000 Berkshire Class A shares, a deal valued at nearly $450 million, chatter went into overdrive. Did the sale of supervoting shares signify that a large holder was looking to off-load even more shares in the coming days? And if that happened, would the downward pressure of a big seller offset the gains Berkshire holders were betting on for Friday, the day dozens of S&P index-fund managers would need to buy shares? Goldman Sachs Group was rumored to have handled the trade; did that mean the firm also was the buyer? Perhaps the buyer was a large fund manager, like Fidelity Investments, that would need shares to put in to its index funds. All of this jockeying for position might mean that interested parties largely have squared their books ahead of Berkshire's inclusion in the S&P 500 and it will pass with barely a ripple. But plenty of hedge funds are betting on a bout of volatility.