It won't surprise many that Warren Buffett's Berkshire Hathaway has been active in the takeover arena. Berkshire made investments in Goldman Sachs (GS - Get Report), General Electric (GE - Get Report) and Bank of America (BAC - Get Report) as they faced crisis -- and announced a $10.7 billion holding of IBM (IBM) on Monday.Berkshire Hathaway has been the biggest investor buying $48.4 billion worth of companies over $250 million in size since the crisis erupted in September 2008, according to Bloomberg data. Its biggest purchase, railroad Burlington Northern Santa Fe, has added over $15 billion in sales to Berkshire's overall revenue of $136.2 billion and is, as of 2010, the most profitable wholly owned company within the investments behemoth. Berkshire's also made big acquisitions in a chemicals company Lubrizol for $ 9 billion and in an aircraft lease company Wesco Financial. Not all Buffett bids have been so clean. In December 2008, Constellation Energy (CEG) cancelled a $9 billion Berkshire buyout in favor of a deal with Electricite de France. After that deal fell through, Constellation was later bought by Exelon (EXC) for $7.9 billion in April of this year, however the deal has come under regulatory scrutiny and isn't complete. This fall, re-insurer Transatlantic Re also rebuffed a $3.25 billion bid by Berkshire. Overall, deal making propelled Berkshire to record one of its best years in profits and revenue in 2010, however shares are down nearly 6% year-to-date and are well below pre-crisis highs.