IndiGo co-promoter Rakesh Gangwal is set to pare his stake in IndiGo by a further 4 per cent via block deals on Thursday, sources said. This would be the Gangwal family's second such share sale in six months. Last September, Rakesh Gangwal and his wife Rekha sold 2.74 per cent in InterGlobe Aviation, mopping up Rs 2,005 crore.About 15.6 million shares (4.05 per cent) stake in aviation firm InterGlobe Aviation (IndiGo) are set to be offloaded via block deals on Thursday. According to the sources, the stake put on the block belongs to the Gangwal family, which currently holds nearly 34 per cent in the airline. The base price for the share sale has been set at Rs 1,875, about 5.6 per cent discount to last close. At the base price, the sellers will be able to mop up over Rs 2,900 crore ($350 million). Shares of IndiGo finished