Why the downsizing

Recently Morgan Stanley said that they would ahve to cut jobs, about 1,000 brokers to be exact. The firm says that they will see those who are not up to the standards of the company and then let them go. Why the reason for the sudden downsizing? Did they have a surplus of investment bankers? Are citizens not needing the help of investment bankers to invest their money as much as they used to? Perhaps the stock market is down, but from what I have heard, investment banking is extremely difficult and it takes a lot of intelligence to be one, so the ones that are not "up to standard" aren't by any means underqualified.