Wealthy hedge fund operator Rajaratnam and a co-defendant pleaded not guilty on 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 defence attorneys 100 hours of intercepted phone calls made over eight months that they say implicate the defendants.

Mr. Rajaratnam and Danielle Chiesi entered their pleas before US 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 US 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.

Mr. Holwell declined to set a trial date but said he may eventually agree with prosecutors and schedule a summer trial.

Mr. Klein also said evidence against the defendants includes post-arrest statements.

The Sri Lankan-born Rajaratnam, 52, of Manhattan, with an estimated $ 1.3 billion in net worth, and Chiesi, 43, of New York City, were indicted on conspiracy and securities-fraud charges after their October arrest. Both free on bail, they were friendly to one another in court.

US Attorney Preet Bharara said at the time of the arrests the case marked the first time prosecutors had made extensive use of wiretaps in a hedge fund insider trading case.

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