Advertising and public relations giant WPP said it has acquired a majority stake in out-of-home advertising specialist Financiere Postiere.The FTSE 100 group did not offer any financial details on the transaction, although it said the deal will be carried out by Kinetic and GroupM, two of its fully owned subsidiaries.France-based Financiere Postiere, which manages media planning and buying for agencies and direct clients, will continue to be led by its current chief executive, WPP said in a statement on Thursday.The group reported consolidated revenue of €9.8m (£7m) last year with gross assets worth €8.5m."This investment continues WPP's strategy of investing in important markets such as France, where WPP companies, including associates, collectively generate revenues of around USD800 million and employ approximately 5,000 people," the company said.WPP shares were down 0.13% to 1,582.00p at 12:38 on Thursday.