The offline media account is worth $218 million, according to COMvergence, while the financial services giant handles its $200 million digital account media in-house.
Pharmaceuticals giant spends estimated €900m a year.
Former AB InBev CMO Miguel Patricio joined the food marketer as chief exec last summer.
Process takes place as Unilever considers selling off tea business.
Food giant will also increase working media spend by 30%, with even bigger boost for key brands.
The review includes work around sustainability, according to people with knowledge of the matter.
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