Obviously, price discovery on the mainstream market, without dark pools information, becomes inefficient.

FORBES: Dark Pools: The Menace Of Rising Opacity In Financial Markets

All dark pools do not disclose the identities, but after that there is a wide range of ways dark pools handle order information.

FORBES: Don't Be Afraid Of The Dark Pools

The SEC staff is looking at requiring disclosure of post-trade information to show which dark-pool operator is executing which trades, according to people familiar with the matter.

WSJ: Ban on Flash Orders Is Considered by SEC