Mainboard IPO GMP vs SME IPO GMP » – What's the Difference? The Grey Market Premium (GMP) plays a key role in IPO analysis, but did you know it differs between Mainboard IPOs and SME IPOs? While Mainboard IPO GMP tends to be more stable due to higher investor participation and stricter regulations, SME IPO GMP can be highly volatile, reflecting lower liquidity and niche demand. Learn how to evaluate GMP trends, subscription data, and allotment status to make smarter IPO investment decisions.