Companies in the Marsh & McLennan group will move to a new Melbourne office in 2013, centralising the group’s presence in the city.

About 2000 employees of Marsh, Mercer, Guy Carpenter and Oliver Wyman will relocate from separate existing offices to Collins Square in the Docklands precinct, where the group has signed a 15-year lease worth about $260 million on a new development.

Australian Country Head Peter Promnitz says by sharing resources and leveraging the group’s combined scale “our operating companies will become more efficient, creating greater value for our people, clients and, ultimately, our shareholders”.

The move will make Melbourne the group’s third-largest office after New York and London, and Mr Promnitz says it confirms the strength of the companies in Australia and the region.