Just weeks after the sale of Merrill Lynch to Bank of America, the architects of the transaction are coming under fire.

John Thain, the Wall Street whizz who took over as Merrill's chief executive just more than a year ago, was lauded for saving Merrill on a dramatic September weekend that saw the collapse of Lehman Brothers. Kenneth Lewis, the long-serving chief of Bank of America, was seen as engineering a deal that capped a career of savvy deal making.