Publicis and Omnicom have announced a merger to create the world's biggest advertising company worth $US35.1 billion.
Omnicom chief executive John Wren and Publicis Groupe boss Maurice Levy are to become joint CEOs.
Each firm's shareholders will hold about 50% of the new Publicis Omnicom Group.
The company will be listed in Paris and New York and will employ more than 130,000 people.
Among industry names in the combined company are BBDO, Saatchi & Saatchi and Leo Burnett.
"John and I have conceived this merger to benefit our clients by bringing together the most comprehensive offering of analogue and digital services," said Mr Levy.
The companies see savings of $US500 million from the merger and the BBC reports the deal is expected to be finalised by the end of the March 2014. The holding company based in the Netherlands.
