A combined Publicis & Omnicom would have revenues of $35bn and 130,000 employees

"Publicis and Omnicom have confirmed that they are to merge to form a partnership of equals to create Publicis Omnicom Group, which will initially be led by John Wren and Maurice Levy as joint CEO’s, with Levy set to step back to a non-executive role following a 30 month period.
The new entity will merge revenue of $22.7bn and €17.7bn (Publicis) and $35.1bn / €26.5bn (Omnicom) and see it overtake WPP as the world’s largest advertising network group, although the overlap is still uncertain, however Wren revealed a figure of $6bn in Omnicom billings from shared clients during the press conference.
The resulting entity will move forward with a combined revenue of around $35.1 billion / €26.5 billion.
Shared clients include Procter & Gamble, L'oreal and McDonalds, while potential conflicts may transpire between Coca-Cola and Pepsi, Microsoft and Google and Verizon and AT&T. The deal was unanimously approved by the board of directors with shareholders from each company holding exactly 50 per cent each.
The new entity will employ around 130,000 people and will include agencies such as BBDO, Saatchi & Saatchi, DDB, Leo Burnett, TBWA, Razorfish, Publicis Worldwide, Fleishman-Hillard, DigitasLBi, Ketchum, StarcomMediaVest, OMD, BBH, Interbrand, MSLGROUP, RAPP, Publicis Healthcare Communications Group (PHCG), Proximity, Rosetta, CDM, ZenithOptimedia and Goodby, Silverstein & Partners, with no mergers between these having yet been announced."

Source:  The Drum, 28th July 2013