Private electronic exchanges.
Then they place orders on the electronic exchanges, hoping to make a small amount per share.
Electronic exchanges, by contrast, can see liquidity dry up at times of stress.
The missteps also raise concerns about how electronic exchanges have handled recent initial offerings.
The investigation exposed electronic exchanges between traders discussing the fixing of Libor.
Their electronic exchanges soon ranged over jazz, dogs and other mutual interests.
Eventually, he predicts, most financial products will be traded on competing electronic exchanges, or alliances of exchanges.
(Whether the electronic exchanges should then compensate the brokers is an issue that could also be explored).
As stock trading has shifted to high-speed computers and electronic exchanges, trading costs have dropped sharply.
"Electronic exchanges in most other countries only accept limit orders," said Professor Harris, a former S.E.C. chief economist.
Their electronic exchanges had begun abruptly in February or March, when she was out with stomach flu.
