SpiceJet's shares tanked 11% on Monday after a report claimed that Indian-American billionaire Rakesh Gangwal doesn't have the "remotest" interest in the airline and isn't seeking to buy a stake in it. Gangwal wants SEBI to investigate the root of "baseless" rumour about him seeking to buy a stake in cash-strapped SpiceJet, the report added. Gangwal is Co-founder of IndiGo.