For Bank of America Corp, the largest U.S. lender, it's not a matter of what or who, but how much.   Of course, we're referring to claims for losses and refunds on soured mortgage loans and failed investments.  Take, for example, claims from Fannie Mae and Freddie Mac - the bank now says they may cost more than previously forecast.  As a result, its shares fell nearly 8% on Thursday, and some 15% over two sessions. 

New demands for refunds on soured loans from the 2 U.S.-owned mortgage firms are coming " in numbers that were not expected based on historical experience," the company said in its report for the 2nd quarter.  What this means is that the $30 billion of expenses booked by the bank since Brian Moynihan became CEO still may not be enough to clean up the faulty mortgages inherited from former CEO Kenneth Lewis.   Back in June, BofA told investors that actions taken during the second quarter probably would cover any further buybacks - unless Fannie Mae and Freddie changed their stance.

According to UNC professor Tony Plath, based in BofA's hometown of Charlotte, NC: "  I don't think it's anything nefarious, it's just that they don't know what the magnitude of losses in that portfolio will be - and until they do, none of their numbers have credibility."

In Monday morning trading, BAC shares traded as low as $7.39, reflecting an intra-day fall of about 9%.  Needless to say, it's by far the biggest loser in the financial sector.   

And then there are reports that Delaware is challenging the $8.5 billion settlement deal that Bank of America recently signed, as well as the entry of New York state Attorney General into the fray.  But that's another story - among others.   [Bloomberg,   8/5/11]

Note:  Also, see C-I's related stories about Bank of America - being sued by AIG - posted 8/8 in our Who's News pages.