The SEC wants to know if stock and option markets should honor an intermarket system of price and time priority.
Under this system, a participant coming to market first with the best price receives priority execution. Time priority between stock markets does not exist, and options marts have no linkages.
Regarding stock trading, the SEC in February (Release No. 34-42450) asked for comment on the old idea of a central limit order book. This concept has taken on a new luster with the Internet's promise of electronic linkage. But it has also sparked debate about who--if anyone--would run the book.
Another February release (No. 34-42456) asks for comment on linkage proposals submitted by five options markets.