It sounds as though they have created an institution which is 'too big to fail'.
Perhaps this is of a size whereby if it gets into trouble an attempt by the US government to guarantee it would bankrupt them?
How would a bail-out if it became necessary compare in size to the F & F bail-out?
EDIT:
Why the heck is BOA paying over the odds for Merril Lynch?
Something smells very, very fishy to me, and my guess would be that taxpayers money and/or guarantees are being funnelled surruptitiously:

Without this buyout announcement Merrill Lynch (MER) would have gotten absolutely crushed Monday. That is absolutely certain. The closing price of Merrill Lynch was $17.05 on Friday. Mother Merrill's market cap was roughly $26 billion.

Thus... Bank of America (BAC) agreed to pay $44 billion for a company that would have been worth $18 billion on Monday's open, assuming a $5 markdown on Monday to $12. Why?

No one had any cash to buy Merrill other than BAC - so what's the rush?

http://seekingalpha.com/article/95414-bank-of-america-merrill-shotgun-ma...