As the world's largest independent media buyer, Aegis is determined to block any attempt by French billionaire Vincent Bollore to gain boardroom representation, according to the Guardian Unlimited (via MediaBuyerPlanner). While Bollore has told Robert Lerwill, chief executive of Aegis, that his growing stake in the company - now up to 25 percent - is purely financial, he is expected to seek influence over the company.

Aegis is likely concerned that Bollore's behavior on the Aegis board would mirror his behavior on the board of Havas: When his stake in the French business reached 22 percent earlier this year, he won four seats on the board and soon ousted chairman and chief executive Alain de Pouzilhac.

Havas controls an estimated 4 percent of the global media buying market, while Aegis controls approximately 9 percent. Aegis is expecting Bollore to take his stake to 29.9 percent, the most that a company can hold without having to launch a bid.