US-based Omnicom Group Inc and France's Publicis Groupe SA announced on Sunday they had signed a definitive agreement for a merger of equals, which will create the world's biggest company in communications, advertising, marketing and digital services.

The new company will have combined 2012 revenue of $22.7 billion. Based on its closing price on July 26, Publicis Omnicom Group will have a combined equity market capitalization of approximately $35.1 billion.

The merged group will have more than 130,000 employees, who will be jointly led by Omnicom CEO John Wren and Publicis Groupe CEO Maurice Levy.