Morgan Stanley's (MS) Brian Zakutansky is taking over some of the bank's mortgage-bond trading, according to three people familiar with the move. 

Zakutansky is replacing James Nimberg, who left last week to join a hedge fund. 

Zakutansky will oversee trading over agency mortgage-backed securities.

Before coming to Morgan Stanley, Zakutansky spent a year working at the U.S. Treasury Department where he participated in the department's work on housing policy.