Morgan Stanley just gave its senior leadership bigger roles

Morgan Stanley

Morgan Stanley President Colm Kelleher.

Morgan Stanley is giving its senior executives broader responsibilities when COO James Rosenthal steps down at the end of the year.

President Colm Kelleher will take over as chairman and CEO of Morgan Stanley Bank, N.A., a national bank subsidiary of Morgan Stanley, according to an internal memo signed by CEO James Gorman.

Kelleher took over as sole president of the firm in January when his copresident, Greg Fleming, left.

CFO Jon Pruzan will oversee strategy execution, going forward, while Vice Chairman Tom Nides will take over operations and corporate services, according to the memo.

The technology division, meanwhile, will report to Robert Rooney, who is the chief executive of Morgan Stanley International.

Rosenthal has been with the firm since 2008 and announced in October he would retire at the end of the year. He will continue to serve as a senior adviser.