More recently, high-frequency traders took some of the blame for the so-called flash crash last May, in which the Dow Jones industrial average plunged nearly 900 points in 15 minutes.
Regulators should spend more time looking at the dangers arising from these newfangled funds, said Marshall Auerback, who works at Madison Street Partners, a hedge fund in Denver.
"You are always responding to the last crisis, not anticipating the next one," Auerback said. "Is this the really big problem [prosecutors] should be focusing on right now? Probably not."
The investigations have given the hedge fund industry a black eye and led investors to withdraw money from firms that received subpoenas — even those that have not faced any charges of wrongdoing.