BOSTON, Mass: World number four advertising conglomerate Publicis Groupe on Wednesday signed a $1.3 billion (€986.1m; £661.6m) "definitive merger agreement" with leading US new media and direct marketing agency Digitas.

With 2,050 staff based in nine US-based offices and one in London, Nasdaq-listed Digitas is a prime catch for the French-owned group, as chairman/ceo Maurice Lévy admitted to the Financial Times.

Not only will Publicis benefit from Digitas's "cutting-edge expertise" in measuring the efficiency of online advertising, the creation from scratch of a comparable digital operation "is something that would have required years to build".

Concedes Lévy: "It is not something that we could have created instantaneously. What we can see is a huge migration of investment from traditional media to online media."

He also revealed that Digitas's two largest clients - General Motors and American Express - are comfortable with the planned acquisition.

Data sourced from Financial Times Online; additional content by WARC staff