Merrill Lynch has decided to buy nonprime lender First Franklin from National City for $1.3 billion. The acquisition fills out the Wall Street firm’s mortgage platform since it already owns a prime and jumbo lender. Buying First Franklin “accelerates our vertical integration into mortgages,” said Dow Kim, president of Merrill's global markets and investment-banking group, in a statement. Having the nonprime lender’s healthy origination volume is just what Merrill Lynch thinks it needs to ensure that its securitization...