The IPO market is set to be bustling next week, with 11 companies like Vishal Mega Mart, TPG Capital-backed Sai Life Sciences and fintech firm One Mobikwik Systems gearing up to launch their initial share sales, collectively aiming to raise nearly Rs 18,500 crore.Other mainboard IPOs to be launched during this period are Inventurus Knowledge Solutions Ltd and Blackstone-owned diamond grading firm International Gemmological Institute (India) Ltd.