Morgan Stanley (NYSE: MS) Chief Executive Officer John Mack will step down and be replaced by Co-President James Gorman, who has been running the company’s brokerage and overseeing its merger with Citigroup Inc.’s (NYSE: C) Smith Barney unit.

The 64-year-old Mack will remain as Morgan’s Chairman when Gorman, 51, takes over the CEO post on January 1, the company said.

Mack came under criticism as he scaled back Morgan’s risk profile even as rivals like Goldman Sachs Group Inc. (NYSE: GS) regained momentum as the worst economic downturn since World War II began to wane, according to the Associated Press.

“Gorman has really earned his stripes,” Anton Schutz, president of Mendon Capital Advisors Corp., which owns Morgan Stanley shares, toldReuters. “He did a great job at Merrill, he’s doing a good job at Morgan Stanley, and the timing for a change seems to be good, because we’ve made it through the worst of the crisis.”

Before joining Morgan in 2006, Gorman had held a series of positions atMerrill Lynch & Co. Inc., including leading its global private client business from 2001 to 2005.

Morgan received $25 billion in federal funds under the Troubled Asset Relief Program (TARP) last year, and has since repaid the entire amount to the U.S. government.

Source: Morgan Stanley CEO Steps Down, Will Remain As Chairman