Leo Burnett USA's president and chief marketing officer Mary Bishop is leaving the network next month after continued speculation about her retirement date.
It is reported that Bishop approached executives at the network and at parent company B|Com3 last year expressing her wish to leave.
Senior management are said to have delayed an announcement to keep her resignation separate from the recent redundancies of 200 of its US staff.
Bishop was at the network for 20 years, during which she led its global Procter & Gamble account and developed subsidiaries such as its LeoHealth healthcare agency