Morgan Stanley has named Jim Rosenthal, the bank's head of technology, as chief operating officer, according to an internal memo sent out Tuesday and confirmed by a spokesperson.

Rosenthal, 57, has been responsible for merging Morgan Stanley and Smith Barney's technology and systems under the joint venture created by the two banks in 2009. (Morgan Stanley holds a 51% stake in the venture.)

The combined advisor force of this joint venture is now includes about 18,100 financial advisor who manage $1.6 trillion in assets.

As COO of Morgan Stanley, Rosenthal succeeds Thomas Nides, who held the post for less than a year. Nides left Morgan Stanley late last year to become a deputy secretary for management and resources at the U.S. State Department.

According to the memo obtained by Reuters, Rosenthal is in charge of human resources, corporate communications, marketing, community affairs and corporate services. He will continue to manage IT for the joint venture.

Rosenthal has served as head of technology and operations since 2008 after joining the firm in March 2008 from Tishman Speyer, a commercial real-estate firm. He worked at Lehman Brothers from 1999 to 2005 and McKinsey from 1986 to 1999, and is a graduate of Yale University and Harvard Law School.

After experiencing client withdrawals of nearly $8 billion in assets during the second quarter, Morgan Stanley’s U.S.-based advisors produced net inflows of $2.4 billion in the third quarter.

The company plans to report its fourth-quarter earnings on Jan. 20.