In its simplest form a dark pool is just an off market understanding and trade between two parties. Which is perfectly legitimate and happens in all kinds of markets. But of course, the term is coined to accommodate HFT, which is a completely different ball game. I am sure as our market mature, we will need something like this because there is no other way to execute large volume trade efficiently.

@zord189 did that banner for me! Damn! That's years back. He is still active and a great animation artist, solid steemian.