Bank of America held a pitch, which was contested by Lippincott and Interbrand, for the project, which will be serviced globally, with delivery from both 's London and New York offices.
The Brand Union already had an existing relationship with Bank of America and created its original identity in 1998.
Crispin Jameson, worldwide chief strategy officer at The Brand Union and team leader for Bank of America, said: "Brands of this stature and complexity require careful handling.
"We are delighted to have been asked to support them in creating a new entity that is greater than the sum of its parts."