Darren Poynton, group chief financial officer, and Mark Connolly, managing director of investment and solutions, are among those who are expected to exit. Both were recruited in 2015.
Yvonne O’Brien, group chief insight and data officer, who also arrived in 2015, and Darren Minshall, chief talent officer, who joined last year, are also poised to leave.
Havas veteran John McLoughlin, chief operating officer of FullSix, is another expected to depart.
There are a number of reasons for the departures, with some people said to be leaving because of a duplication of roles following the merger of Havas’ creative and media divisions into a new office, Havas Village, in London’s King’s Cross. A source dismissed suggestions that Havas is keen to cut costs.
The exodus comes just as Vivendi, which is chaired by Vincent Bolloré, completed its €2.3bn acquisition of Bolloré Group’s 59% stake in Havas on Monday.
A Havas spokesman said: "The move to King’s Cross has transformed our business as evidenced in our new-business performance. These changes are consistent with our Together strategy as we continue to streamline and move towards a single P&L business."
Havas reported a 0.5% rise in UK revenues in the first quarter of 2017.