This system has an honor code: despite temptation, no broker should trade just for commissions.

Recent discussions center on the concept of dual trading, which allows brokers to trade for their own accounts as well as customer accounts.

These brokers often traded stocks that were speculative in nature.

Instinet is an electronic system that allows brokers and institutional investors to trade stocks.

The tipped off brokers traded on the information.

Daniel Rappaport, the chairman of the exchange, estimated that 100 brokers traded in the electricity market yesterday.

The plan was that brokers could eventually trade over the system, which would be connected by satellite to Merrill's central computers.

The broker traded anyway, setting up a margin account that, by investing with borrowed money, amplified the risks.

And the upheaval in the secondary markets, where dealers, brokers and investors trade bonds after they are issued, is bound to prove more profound.

The broker can also trade in a best effort way and answer to the client the realized price.