gray market

The gray market (sometimes spelled as "grey market") is the collective system of unauthorized sales channels for products. 

Gray market products may be less expensive than those bought through official distribution channels but are sometimes inferior. The products may be counterfeit or have counterfeit parts, for example; they may be second-hand products or contain second-hand components that are represented as new. In some cases, gray market products are authentic but distributed illegally, perhaps to exploit variations in costs and prices in different parts of the world. Warranties, updates or other support are usually not available for gray market products.

The term gray market reflects the somewhat ambiguous middle-ground between the completely legal products sold on the white market and the clearly illegal products sold on the black market. 

In the stock market, the gray market involves the trading of new issues of shares before they're officially available. In this context, the gray market is also sometimes referred to as the parallel market.