Mergers can be difficult because of cultural differences between firms. In 2008, Bank of America bought Merrill Lynch, a stockbroker. Their cultures and pay packages were starkly different. After the merger, in 2009, leading brokers of Merrill began departing for friendlier waters. Some went to Morgan Stanley, and some became independent brokers. The rating agency, Standard & Poor's, called the departures a "cause for concern," adding that "if brokerage attrition picks up, the acquisition becomes less valuable." Divided cultures in one firm can be O a competitive advantage. a competitive disadvantage. O an opportunity to change the culture