The stock of Fonebox made an impressive debut, listing at a 185.7 percent premium over the IPO price, on February 2 and opened at Rs 200 against the issue price of Rs 70 on the NSE SME platform. Ahead of the listing, Fonebox shares were trading at a 185 percent premium in the grey market, which is an unofficial ecosystem where shares start trading before the allotment in the IPO.