After a year of unrelenting criticism, shareholder litigation, regulatory bullying, hostility from lawmakers and an embarrassing reliance on taxpayer funds, Ken Lewis, Bank of America chief executive, still has one trump card he can play in the debate about whether BofA should ever have acquired Merrill Lynch: the deal makes profound strategic sense.

It is apparent that after a frenetic weekend of negotiations, BofA’s $29 per share all-stock offer for Merrill Lynch, a year ago on Monday, was far too rich given the quantity of toxic assets buried deep within Merrill’s balance sheet and the worsening condition of global financial markets.