IndiGo to file prospectus for $400 mln float next week - sources

SINGAPORE/MUMBAI (Reuters) - India's biggest airline IndiGo is set to file the prospectus next week for a domestic stock market listing, expected to raise as much as $400 million, three sources with knowledge of the matter said. IndiGo, owned by hospitality and travel company InterGlobe Enterprises, is aiming to get approval from India's market regulator in August, before hitting the market later in the year, one of the sources said. IndiGo, founded in 2006, has used its low-cost model