John Mack will step down at year's end as Chairman of Morgan Stanley, clearing the way for CEO James Gorman to assume that role.   The decision to have Mr. Gorman succeed Mr. Mack as chairman was widely expected. Mr. Mack, who's only 66, has served as chairman since 2010.  Among his numerous options, he's likely to take a senior advisory role with the firm.  He's working on a book about leaders and his years on Wall Street, that's scheduled to be published September 2012.  Mr. Mack can join other corporate boards;  he already sits on a number of not-for-profit boards and is chairman of the panel of economic advisers for the Republican presidential candidate Jon M. Huntsman Jr. Finally, John Mack was named on a short list of possible candidates to replace Brian Moynihan as CEO of Bank of America - some on Wall Street are already burying Mr. Moynihan.  However, it was believed that Mr. Mack would pass on such an opportunity - preferring to step into semi-retirement. Recent Wall Street Career. Mr. Mack, 66, is one of Wall Street’s best-known figures. He worked at Morgan Stanley for years, rising from bond salesman to become the firm’s president.  After a long-running dispute with Morgan Stanley CEO Philip Purcell, he left the firm in 2001.  He soon resurfaced at Credit Suisse, however, where he became CEO of the CS First Boston investment bank, and later co-CEO of the parent company, the Credit Suisse Group. At Credit Suisse he lived up to his nickname "Mack the Knife," drastically reducing jobs and cutting costs.  But the relationship, in the end, was ill fated.  At one point he proposed merging CSFB with another investment bank.  The Swiss bank’s board disagreed and his contract lapsed in 2004. In 2005, after an uprising at the bank against Mr. Purcell, the Morgan Stanley board asked Mr. Mack to return as CEO.  On his first day, upon arriving onto the trading floor, Mr. Mack received a standing ovation.  Since that point, however, his record at Morgan Stanley has been mixed.  He ramped up risk after returning to the firm, giving it some of its former swagger, but he was unable to pull it back in time in 2007 and 2008 as the New York bank sustained significant losses. Morgan Stanley in Recent Times. During the financial crisis, Morgan Stanley required billions in emergency support from the federal government, and a large investment from Japanese bank Mitsubishi UFJ Financial Group in order to survive. Mr. Mack received credit for negotiating the Mitsubishi deal, convincing the Japanese bank to move ahead with the partnership despite the difficult environment. Mr. Gorman has been running the day-to-day operations of Morgan Stanley since 2010 - working to turn around the firm’s fortunes, reducing risk and rebuilding units that were injured during the credit crisis.  He's received credit from analysts for his efforts, although MS's stock, like that of other financial firms, continues to languish. Morgan Stanley will be combining the role of CEO and Chairman.  Wall Street is now split on this issue - with Citigroup and Bank of America splitting the roles, while Goldman Sachs and JPMorgan Chase - and soon Morgan Stanley - have combined it.   [Dealbook, 9/15/11]