The plan would see the watchdog attach unique identifiers to traders that aren't registered market makers or broker-dealers, according to anonymous sources cited by the Wall Street Journal.

The agency is undertaking a cost-benefit analysis of the process, and is expected to move forward with a proposal in the near future, says the paper, citing "several people familiar with the process".

The tagged trading data, released a day after transactions were executed, would be available only to regulators, say the sources.

The initiative is the latest move in a global effort to re-write the rule book for a new era of high-speed automated trading.

Last week, the Committee of European Securities Regulators (CESR) kicked off a review of "technology driven" developments in European trading as part of the EU's revision of the Markets in Financial Services Directive (MiFID).