US prosecutors and the Securities and Exchange Commission's internal watchdog recently probed the personal financial holdings of some SEC employees in New York, a move that could again shine a spotlight on the agency's internal compliance efforts, people familiar with the situation said.

The SEC more than four years ago overhauled its procedures for monitoring employees for potential trading abuses after drawing criticism as a result of an insider-trading probe. However, the agency hasn't enacted key improvements it initially intended to put in place, including monitoring employee securities trading using brokerage-account data, current and former SEC employees said. Some procedures remain the same as those criticised as an "honor system".