Bank of America 10bn$ capital raise

How on earth a bank that spends 50bn$ to buy Merrill Lynch would after a month need to raise 10bn$ at a discount of some 20/30% versus market price, diluting existing shareholders, in a market that is extremely tight on cash? It seems to me that some people might not have understood how serious the situation is, if they think they can go shopping and later easily present the bill to shareholders.