The plan, called "the G5 pilot", would enable automatic information exchanges.

BBC: Deputy Peter Harwood

Stocks trade on dozens of exchanges, automatic trading systems, dark pools and crossing networks these days, and trading in futures and options markets affects trading in the cash markets.

FORBES: SEC Wants Real Time Trading Data

An ECN can provide automatic transactions and quotations for securities, including those listed on the exchanges.

FORBES: Electronics Communications Networks (ECNs)