As the name implies, Gray Market or gray market sells goods legally, but without going through the official distribution process set by the manufacturer or brand holder.
It is said to be gray because this market is between the legal or official market (white) and the illegal market (black), so that the goods sold do not violate the law, but also do not fully comply with existing distribution regulations.
In securities, the gray market itself is a market where stocks and other financial instruments are traded informally, before they are officially listed and traded on the stock exchange.