Reuters: Bank-run dark pools swelling in U.S. stock markets

Big banks are executing an increasing percentage of U.S. stock trades within their own walls, capitalizing on the credit crisis and enticing the most active traders away from the traditional exchanges.
"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.
The bank-run dark pools have only recently gained some traction in Europe, while other countries, such as Canada, are watching closely for signs of success or failure as U.S. equity markets fragment into some 40 venues.