But some ad execs are questioning if the new partnership will actually hurt staff and clients.
Havas CEO David Jones said in a statement, "I'm not sure this is in the best interests of their clients or their talent. Clients today want us to be faster, more agile, more nimble and more entrepreneurial, not bigger and more bureaucratic and more complex."
And can it be more agile at such a large scale? Particularly "in a world where digital and technology have made scale irrelevant."
Jones continued, "Our business is very simple - it's about clients and talented employees - and as I said, I'm not sure this move is good for either of them."
But Omnicom CEO John Wren said at the press conference today that "anyone who is concerned about any of this should not be."