More traders swimming in the "Dark pools"

"Dark pools," where orders are anonymously matched so that traders do not alert the wider market to their intentions, have triggered concerns that stock pricing may not be transparent.

But the growth of those run by broker-dealers such as Goldman Sachs and Credit Suisse are squeezing other "dark" electronic trading venues, as well as exchanges, resulting in lower fees..

But regulators, exchanges and others have raised concerns that dark pools do not publicize their quotes, that there is a general lack of comprehensive data on them, and that some provide early messages, or "looks," to specific market players about upcoming orders.

"I am concerned that (undisplayed quotes) may not promote public confidence in the equity markets," James Brigagliano, co-acting director of the U.S. Securities and Exchange Commission's trading and markets division, told a major market structure conference in New York last month.
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