Bollore had raised his stake to 21.05% early on Friday, having taken it to 20.8% last week, as WPP Group and Hellman & Friedman were given until November 25 to make an offer for Aegis by the Takeover Panel.
The panel made the ruling following a request by Aegis for a deadline to be drawn up for the long-winded process. Robert Lerwill, chief executive of Aegis, has also said in the press that he wants WPP to make a decision "sooner and not later".
WPP has made no indication as to how much it is willing to pay to win Aegis. If it does buy the company, the UK media buyer will likely be broken up, with Sir Martin Sorrell's firm taking control of market research firm Synovate and the rest going to Hellman & Friedman.
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