Advertising giant WPP has agreed to buy an 80 per cent majority stake in the WVI Group, a joint venture holding company for a number of WPP brands in Russia.The deal is subject to regulatory approval. An agreement has also been made to purchase the remaining 20% stake in 2016. "This investment continues WPP's strategy of developing its services in fast-growing and important markets and sectors," WPP said in a statement. "WPP companies (including associates) in Russia have revenues of over $300m and employ over 2,000 people."The WPP brands that WVI Group holds in Russia include media investment management businesses Maxus, MEC, MediaCom, Mindshare, GroupM and marketing communications company JWT.Shares rose 0.15% to 1,366p at 10:39 on Monday.RD