“Dark pools” is the romantic – or sinister, depending on your viewpoint – name given to networks that allow traders to buy or sell large orders without running the risk other traders will work out what is going on and put the price up, or down, to take advantage of the order. They have been criticised for their lack of transparency and because the inevitable fragmentation of trading could lead to less efficient pricing in traditional open stock exchanges. [1]

A type of trading platform that allows large blocks of shares to be traded without the prices being revealed publicly until after trades are completed. [2]

Pre-trade prices - the price at which shares are offered for sale - are not visible to anyone, even the participants in them, and the price at which shares change hands is only revealed after the trade is done. [3]