CFTC investigators are reviewing over one million e-mails and instant messages as part of an investigation into possible price manipulation of ISDAfix interest-rate swaps. The electronic communication search comes just a few months after the records were collected under subpoena for evidence that the world’s largest banks rigged the ISDAFIX swaps rate.

According to Bloomberg.com, the CFTC investigators are investigating whether brokers are colluding with dealers who stand to profit from inaccurate quotes.

This is the second investigation into the manipulation of benchmark rates within the past year. In 2012, regulators fined three banks over $2.5 billion for rigging the London interbank offered rate (LIBOR), which is tied to over $300 trillion of securities worldwide.

As part of the CFTC’s probe, investigators are preparing to interview bankers and brokers in the coming weeks.