Janus said Tuesday it has been subpoenaed in the federal investigation into insider trading by “executive networks,” hedge funds and mutual funds. A day earlier, the FBI raided the offices of three hedge funds in Connecticut and Massachusetts.

Those familiar with the probe, three years in the making, say federal regulators are concerned about the speed at which information is traded today, as well as high-frequency trading that can potentially mask insider deals. This investigation, which regulators have threatened could eclipse any insider-trading investigation to date, might redefine insider trading, insiders say.

The U.S. Attorney in Manhattan, Preet Bharara, who is spearheading the investigation, has said it is difficult to detect insider trading through traditional investigative means, so wiretaps are necessary.