Continuing a string of acquisitions of originators by Wall Street firms, Merrill Lynch this week announced it is set to acquire First Franklin Financial from National City Corp. for $1.3 billion. And in a separate transaction, Merrill Lynch also expects to buy about $5.6 billion of First Franklin’s loans from National City. The moves come on the heels of Morgan Stanley’s acquisition of Saxon Capital. Deutsche Bank and Barclays also recently acquired originators to feed their mortgage-backed securities business...