• by Joe Mandese  @mp_joemandese, September 28, 2005

Amid a whirlwind of stock trading activity, French corporate raider Vincent Bolloré has increased his stake in Aegis Group to 8.04 percent from 6.04 percent fueling speculation that he may be mounting a takeover. The move follows Public's Groupe's announcement that it has held preliminary talks with the Aegis board about acquiring the London-based media buying and marketing research holding company. Publicis also continued to buy and sell shares of Aegis stock over the past several days, though it has yet to amass enough of a stake to register among Aegis' major shareholders.

The increase in Bolloré's position, which came as a result of two transactions made on Monday, places him as the second largest shareholder behind Harris Associates, a Chicago-based fund manager that has influenced the outcome of other big ad agencies in the past. According to executives familiar with Harris' holdings, the firm also manages a sizeable stake in Publicis and may be poised to broker a deal.

The stakes are managed by Harris' David Herro, who is known as an "activist" manager who came to fame on Madison Avenue when he influenced the ouster of Maurice and Charles Saatchi from the agency that bears their name in 1994, but which is now part of Publicis.

Amid the Madison Avenue speculation, several research firms also are said to be eyeing Aegis' research assets and could become a factor should the company officially go into play.

Bolloré, meanwhile, has made hundreds of millions since taking his initial stake in Aegis last month, but may be looking for more than a cash return on his investment. He is also the biggest shareholder of Paris-based agency holding company Havas, which is in dire need of a major strategic move such as a big acquisition.