Banks lose top brokers all the time, and so far the exits have not affected the wealth management and investment management unit's bottom line. That group, which includes the U.S. Trust unit in addition to Merrill's retail brokerage, posted record revenue and profit in the third quarter. The bank's wealth management arm has long been a high-performing business. For years, Merrill Lynch brokers, known as the "thundering herd" because of their bull logo and their large numbers, have been among the most productive on Wall Street, in terms of revenue generated. When Bank of America executives announced that the bank was buying Merrill Lynch in September 2008, they made special note of how attractive the wealth management business was to them. The latest moves come around six months after Thiel reshuffled the top ranks in an attempt to boost productivity.