The Securities and Exchange Commission is conducting a cost-benefit analysis of tracking transactions of high-frequency trading firms. The agency is expected to move forward with the effort, sources said. The idea is to give each firm a unique identifier that would allow the SEC to monitor traders not registered as a broker-dealer or a market maker. "The SEC can get any data they want, period, but right now it's kind of cumbersome because they have to go through the clearing firm," said a securities lawyer. "This would make it more automated."