The move, part of a broader executive shuffle that also moved Franck Petitgas from co-head of investment banking to head of Morgan Stanley's international business, was disclosed in an internal memo seen by Reuters on Tuesday.

Pick, 49, started his career at Morgan Stanley in investment banking and later moved to trading. He ran the bank's equities trading business, which became a key money-maker as it struggled in other businesses, and then helped orchestrate a difficult overhaul of its fixed income operation, which had weighed on results for years. (http://reut.rs/2oKRVTo)

Chief Executive Officer James Gorman and President Colm Kelleher, 61, who previously led the institutional securities business, called the promotion "a natural next step" for Pick in the memo. Pick's shift to a role that Kelleher has long overseen is important because it hints at succession planning at Morgan Stanley.

While there is no indication Gorman has plans to retire soon, and though Kelleher is his deputy, the process to find a next long-term CEO can take years to cement. Petitgas has also been mentioned as a potential successor among analysts, former executives and others who closely follow Morgan Stanley.

In addition to Pick's elevation, Susie Huang will become co-head of investment banking alongside Mark Eichorn, according to the memo. Petitgas previously had that role.

Pick and Petitgas will report to Kelleher, while Huang and Eichorn will report to Pick.

In a separate memo, Pick appointed Gokul Laroia, David Russell and Alan Thomas as global co-heads of Institutional Equities.

(Reporting by Lauren Tara LaCapra; Editing by Jeffrey Benkoe, Marguerita Choy and Frances Kerry)

By Lauren Tara LaCapra