Merrill Lynch & Co. Chief Executive John Thain is making a pitch to Wall Street: Buy the brokerage's shares while they're still cheap. But investors don't seem ready to listen. In this Oct. 24, 2007 file photo, a man walks into a Merrill Lynch office in Menlo Park, Calif.. Merrill Lynch & Co., the world's largest brokerage, is expected to report quarterly earnings Thursday, July 17, 2008.