The BRK-B stock split occurred in 2010, according to the Wall Street Journal. BRK-B entered the S&P 500 immediately after the split. Warren Buffett used the proceeds of the BRK-B split to help fund the purchase of Burlington Northern Santa Fe Corporation, a railroad that cost Berkshire Hathaway $27 billion.
BRKB shares are Class B shares of Warren Buffett's financial services company, Berkshire Hathaway, says CNN. When BRK-B underwent a stock split, the stock's market capitalization remained stable both prior and following the split, says Stock Split History. One reason stock splits are executed to spur greater interest on the part of investors with smaller budgets.