(Reuters) -Shares of Canal+ fell on their London debut on Monday while fellow Vivendi spinoffs Havas and Louis Hachette rose in Amsterdam and Paris, after shareholders of the French media conglomerate voted overwhelmingly in favour of the high-stakes split project on Dec. 9.

Shares of broadcaster Canal+ opened at 290 pence, giving it a market value of 2.9 billion pounds ($3.66 billion), but fell more than 12% from that price to 253.5 pence by 0848 GMT.

Canal+'s decision to list in London, announced in July, was a much-needed boost for Britain's stock exchange which has seen a series of departures and few high-profile joiners in recent years. British finance minister Rachel Reeves on Friday hailed it as a "vote of confidence" in the country's market.

Advertising company Havas rose around 6% to 1.91 euros per share by 0905 GMT compared to their opening price on Euronext Amsterdam. Publisher Louis Hachette's shares were trading at 1.41 euros on Euronext Growth Paris, up 17.5% on the opening price.

J.P.Morgan analysts had estimated Canal+ to be worth about 6 billion euros, Havas 2.5 billion euros and Louis Hachette around 2.2 billion euros.

Vivendi, backed by the Bollore family, resumed trading on Euronext Paris without the spinoffs and remains a part of the blue-chip CAC40 index for now, though it may exit it at a later date, supervisory board chairman Yannick Bollore said.

Lagardere, majority owned by Louis Hachette following the split, also stays listed on Euronext Paris.

($1 = 0.9514 euros)

($1 = 0.7916 pounds)

(Reporting by Gianluca Lo Nostro and Leo Marchandon in Gdansk, Florence Loève in Paris;Editing by Milla Nissi)