the "external crossing" seems becoming a retail side tool

funny when seeing something learned in the books which I thought not very practical becoem true. Wondering what will be the cost external crossing for retail side clients. news: BANKS IN LINK TO LET EACH OTHER’S CLIENTS DIP INTO LIQUIDITY POOLS By Anuj Gangahar in New York Wednesday, May 21, 2008 Goldman Sachs, Morgan Stanley and UBS are to link their private stock trading operations to improve liquidity and better compete with the increasing number of alternative exchanges. The move, to be announced on the 20 May, will give clients of each bank access to the others’ so-called dark liquidity pools – the private interbank or intra-bank platforms widely used to trade stocks away from exchanges. The pools are used by clients such as hedge funds to buy and sell large blocks of shares in complete anonymity and without the danger of moving the public price of a stock on an exchange. The development of dark pools is considered a potential threat to established exchanges. Some analysts suggest the various dark pool providers could eventually join together, combining their individual dark pools and then applying for exchange status. Today’s move stops short of combining the banks’ respective dark pools. “These are access arrangements,” said Will Sterling, managing director, UBS Electronic Trading. “These agreements should offer clients access to additional high-quality liquidity without making their trading process more complex.” The arrangements, which apply at present only to the US, will allow algorithmic trading orders received by each firm to interact with the US equity liquidity found in three of the largest broker-dealer-operated dark liquidity pools in the US – the Goldman Sachs Sigma X, the Morgan Stanley MS Pool and the UBS PIN Automated Trading System. “We’re confident that providing our respective clients access to each other’s liquidity will achieve even better crossing results for our clients in an increasingly fragmented market,” said Greg Tusar, managing director, Goldman Sachs electronic trading. Several other brokers in the US operate dark pools. Mr Tusar said the agreement between the three banks was reached after discussions revealed a similar vision for how their trading businesses should develop. ”This is a natural evolution,” Andrew Silverman, managing director of Morgan Stanley electronic trading, said. “These arrangements will enable us to work with trusted industry participants to deliver the same level of confidentiality our clients have come to expect.”