AdWatch, which has gross assets of EUR9.5 million, has a client roster that includes Microsoft, VTB Bank and Canon. Its 76 staff will become part of Isobar's 3,200-strong global digital network.
The acquisition takes place as Russian adspend is predicted to grow by 20 per cent in both 2008 and 2009. The current figure of 25 million online users is growing at more than 25 per cent a year.
Robert Lerwill, the Aegis chief executive, said: "AdWatch brings us a significant competitive advantage."