Wealthy hedge fund operator Raj Rajaratnam and a codefendant pleaded not guilty Monday to charges they were major players in a scheme that used inside information to make stock trades that generated millions of dollars in profits.

Prosecutors, who have described the case as a "wake up call for Wall Street," promised to hand over to defense attorneys 100 hours of intercepted phone calls made over eight months that they say implicate the defendants.

Rajaratnam and Danielle Chiesi entered their pleas before U.S. District Judge Richard Holwell in Manhattan to an indictment returned last week in a $52 million insider trading case that has resulted in charges against 21 people.

Assistant U.S. Attorney Josh Klein asked Holwell to set a trial date in June or July but defense lawyers balked, saying it would take months to review the audio tapes of telephone conversations between the defendants.

Holwell declined to set a trial date but said he may eventually agree with prosecutors and schedule a summer trial. Klein also said evidence against the defendants includes post-arrest statements.