The Vodafone Group, the world's leading mobile operator by revenue, has bought 10 per cent stake in the Bharti Group for $1.5 billion. The deal represents a return to the fast-growing Indian market for Vodafone, which owns networks in 27 countries and has partners in another 14, after it sold a minority stake in a regional Indian firm two years ago. Bharti chairman Sunil Mittal said the 10 per cent included the entire 5.65 per cent stake of New York private equity firm Warburg Pincus. The other 4.4 per cent will be held through a Vodafone purchase of part of Bharti Enterprises Private Limited.