What does grey market premium meaning?

GMP is a premium amount paid at which initial public offering (IPO) shares trade before they are listed on the exchanges.

The GMP can be positive or negative. A positive GMP indicates that an IPO may perform well after listing, while a negative GMP reflects the poor performance of the IPO. A stock with a higher GMP may list at a good premium, while a stock with a lower or negative GMP may list at a discount.