Ken Lewis, chief executive of Bank of America, has grown accustomed to public scrutiny in recent months. Initially lauded as a Wall Street hero for his high-stakes acquisition of Merrill Lynch in September, he was later lambasted for overpaying for the investment bank and for allowing Merrill to pay staff bonuses amid mounting multibillion-dollar losses.

Mr Lewis, 61, who became BofA's chief executive in 2001, has faced criticism for his acquisitions before. When he led BofA's acquisition of Fleet National Bank in 2004, many analysts expressed scepticism over the price of the deal and the bank's ability to wring value out of the combination.