Under a new SEC proposal, large traders would be issued a unique identification number so that their broker-dealers could maintain transaction records in an effort to stop illegal trading activity.

The SEC voted April 14 to create a large trader reporting system that would enhance its ability to identify large market participants, collect information on their trades, and analyze their trading activity. They would be required to identify themselves to the commission, which would then assign each trader an identification number. Large traders would provide this number to their broker-dealers, who would be required to maintain transaction records and report that information to the SEC upon request.

A large trader would be generally defined as a firm or individual whose transactions in exchange-listed securities equal or exceed two million shares or $20 million during any calendar day, or 20 million shares or $200 million during any calendar month, according to the SEC.