[mcphilip]

A recent WSJ article uses the same terminology [1]. Also, it's common to refer to things as shadowy in financial markets. Shadow banking system, dark pools of liquidity, etc. Calling something a shadow market is a way to describe a market characterized by asymmetric information, basically.

[1] http://online.wsj.com/article/SB1000142405274870389970457620...

[waterlesscloud]

Fair point, though I do think there's a notable difference in implications of "shadow market" and "shadowy market", more than the one extra letter would indicate.