The practice was intended, in fact, to protect institutional traders against the occasional daily losses that result from restless trading.

Right now more problems for Wall Street are being caused by institutional traders who use very active computer-driven strategies.

"We believe in making a market for all investors, not just large institutional traders."

Hedge funds, as well as institutional traders, arbitragers and individual investors, were said to have been big buyers.

But institutional traders have complained that they were unable to execute large orders efficiently in the pits.

"We find that institutional traders react to news, like rumors or changes in analysts' direction," he said.

Individual investors can participate in the first session, while the second is intended for large institutional traders engaged in program trading.

Program Trading is a strategy normally used by large institutional traders.

Program trades, which are almost exclusively practiced by large institutional traders, can create rapid market fluctuations.

These institutional traders, who sometimes move hundreds of millions of dollars around the markets almost instantly, have introduced a new element to the system.