By Tassilo Hummel and Mathieu Rosemain
PARIS (Reuters) -French media group Vivendi (EPA:VIV) said it has boosted its ownership stake in Lagardere to 55% following its tender offer for the whole of the publishing and retail group's shares and extended its bid until June 9.
The merger, which is being reviewed by EU antitrust authorities, would create a new publishing behemoth via the combination of France's two biggest publishing groups, Hachette and Editis.
The tie-up is contested by several independent publishing companies in France and would make Vivendi the world's third-biggest publisher after Bertelsmann's Penguin Random House and News Corp-owned HarperCollins.
Lagardere's second- and third-biggest investors, Qatar's sovereign fund and Arnaud Lagardere, had already signaled they would not sell their shares. Each owns about 11% of the company.
Bernard Arnault's family said it would sell a 2% stake out of the nearly 10% it owns in Lagardere.
Vivendi, controlled by billionaire Vincent Bollore, raised its offer in February and is ready to spend as much as 2 billion euros ($2.13 billion) to acquire all of Lagardere's listed shares.
The extension of the tender offer until June 9 leaves a window open for Vivendi to raise its stake in Lagardere. It has said it did not intend to take Lagardere out of the stock market.
French markets regulator AMF will publish the final results of the tender offer on June 14, Vivendi said.
As of May 20, Vivendi holds 45.9% of voting rights, Vivendi said, but added that in accordance with the terms of the takeover and antitrust rules, Vivendi will use only 22.50% of its voting rights until the takeover is officially cleared by regulators.
The acquisition means Vivendi, which already owns pay TV group Canal+ and right-leaning news channel CNEWS, would also gain financial control over Lagardere's flagship magazine Paris Match, weekly newspaper Journal du Dimanche and radio station Europe 1.
($1 = 0.9376 euros)