U.S. prosecutors charged seven people, described as a circle of friends who formed a criminal club, with running a $62 million insider trading scheme - the latest salvo in a years-long probe of suspicious trading at hedge funds.

The FBI in New York arrested four people on Wednesday and authorities announced previously secret charges against three others, making it one of the largest sweeps in the government's investigation.

The seven charged worked for five different hedge funds and investment firms and reaped nearly $62 million in illegal profits on trades in Dell Inc, the prosecutors said. That is similar in magnitude to insider trading gains made by Raj Rajaratnam, the convicted founder of the Galleon Group hedge fund.

The charging document told by now, a sadly familiar story, Manhattan U.S. Attorney Preet Bharara said at a news conference.

It describes a circle of friends who essentially formed a criminal club, whose purpose was profit and whose members regularly bartered lucrative inside information, Bharara said.

Dubbed Operation Perfect Hedge by the FBI, the probe has examined suspected sharing of confidential business information with hedge fund managers and analysts. Rajaratnam was arrested as part of the investigation and is now serving an 11-year prison term following his conviction by jury trial last year.

The defendants arrested on Wednesday include Anthony Chiasson, who co-founded the Level Global Investors hedge fund. He turned himself in to the FBI in New York, an agency spokesman said. A U.S. magistrate judge released him on $5 million bail during a brief appearance in Manhattan federal court. Chiasson was not asked to enter a plea, but his lawyer, Gregory Morvillo, said his client denied the charges.

Todd Newman, who headed technology trading for hedge fund Diamondback Capital Management from Boston, was also arrested. Diamondback said in a letter to investors on Wednesday that it had been proactively assisting criminal prosecutors and the U.S. Securities and Exchange Commission in the case against Newman and another former employee, Jesse Tortora.

Chiasson and Newman are accused of illegally trading ahead of computer maker Dell's earnings announcements for the first and second quarters of 2008, netting them profits, respectively, of $57 million and $3.8 million. Another defendant, Jon Horvath, is accused of making an illegal $1 million trade in Dell. Horvath was released on $750,000 bail after a court appearance in New York.

In a parallel civil action, the SEC said investment analyst Sandeep Sandy Goyal of Princeton, New Jersey, obtained Dell quarterly earnings information and other performance data from an insider at Dell in advance of earnings announcements in 2008.

Goyal tipped then Diamondback analyst Tortora of Pembroke Pines, Florida, with the inside information, and Tortora in turn tipped several others, leading to insider trades on behalf of Diamondback and Level Global hedge funds.

The fourth man arrested was California-based hedge fund manager Danny Kuo, officials said.

A Dell representative said the company had cooperated with authorities.

The SEC charged Diamondback Capital and Level Global as well as the individuals.

SEC: SYSTEMIC DISHONESTY

At Wednesday's news conference, SEC Enforcement Division chief Robert Khuzami said the cases, along with Galleon and prosecutions of some so-called expert network firms, reflect systemic dishonesty and exposes a deeply-embedded level of corruption.

Newman had been placed on leave of absence from Diamondback in 2010 and subsequently was let go by that firm. Reuters in November reported the government's interest in Newman.

Chiasson, Newman, Horvath and Kuo were charged in U.S. District Court in Manhattan with one count each of conspiracy to commit securities fraud and securities fraud, according to court documents.

Horvath, who was also arrested on Wednesday, is currently employed at Sigma Capital management, a unit of Steven Cohen's $14 billion hedge fund SAC Capital, said a person familiar with the case who is not authorized to speak publicly. A spokesman for SAC Capital could not immediately be reached for comment.

Criminal charges also were made public against Goyal, Tortora and Spyridon Adondakis, a former junior analyst at Level Global who all previously pleaded guilty and are cooperating.

Lawyers for the three men could not be reached to comment.

Lawyers for Newman and Kuo also could not be reached to comment.

FBI Assistant Director-in-Charge Janice Fedarcyk said in a statement that the agency has arrested more than 60 people in the crackdown.

This initiative is far from over, she said. If you are engaged in insider trading, what distinguishes you from the dozens who have been charged is not that you haven't been caught; it's that you haven't been caught yet.

The criminal complaint - signed by FBI agent David Makol, who was assigned to the Galleon investigation - accused Newman and Chiasson of using information obtained by the three cooperators and their network of sources at companies to make illegal trades.

MORE HEADACHES FOR SAC

Horvath's arrest creates more headaches for fund industry titan Cohen, who has not been accused of wrongdoing.

Federal investigators have been looking into allegations of wrongful trading at SAC for more than four years, Reuters has previously reported, and Horvath's arrest comes after criminal cases of others who have been tied to SAC.

Donald Longueuil, a one-time SAC portfolio manager, last year was sentenced to 2-1/2 years in prison for insider trading while Noah Freeman, another former SAC portfolio manager, cooperated with the government and pleaded guilty.

The investigations of insider trading began at least eight years ago and were first made public in October 2009. Most of the dozens of defendants charged have pleaded guilty or been convicted.

Many of the cases have been based at least in part on the use of government wiretaps authorized by federal judges. Four hedge fund firms - Level Global, Diamondback, Loch Capital Management and Barai Capital Management - were raided by the FBI in late 2010. Level Global, Loch and Barai have since folded.

Rajaratnam remains the best-known investor implicated in the probe. Rajat Gupta, a former chief of the consulting firm McKinsey & Co and director of both Goldman Sachs Group Inc and Procter & Gamble Co, has been charged with providing illegal tips to Rajaratnam. He is fighting those charges.

The case is U.S.A v. Todd Newman et al, U.S. District Court for the Southern District of New York, No. 12-0124.

(Additional reporting by Matthew Goldstein and Jonathan Stempel in New York, Svea Herbst-Bayliss in Boston and Poornima Gupta in San Francisco; Editing by Gunna Dickson, Gary Hill and Tim Dobbyn)