Morgan Stanley invited Leo Burnett to compete in the pitch, but in a statement the agency said: "In light of recent changes at Morgan Stanley, Leo Burnett has decided to resign as its advertising agency of record."
The review follows the departure of the Morgan Stanley chief executive, Philip Purcell, and the chief marketing officer, Phil Raskin, earlier this year. Raskin was a former Burnett employee.
Burnett has held the business since 1988, when it won the Dean Witter account. Morgan Stanley took over Dean Witter in 1997.