The number of people charged with insider trading on Wall Street reached 20 Thursday.

U.S. Attorney Preet Bharara said eight people were arrested on securities fraud charges. Another five, who have already pleaded guilty, are co-operating, while a 14th person is still at large, he said.

The Securities and Exchange Commission has alleged the participants made $53 million in illegal profits.

According to papers filed in a Manhattan court, one of those arrested Thursday Zvi Goffer played a central role in the network. Prosecutors suggest Goffer paid others to obtain information about intended takeovers ahead of public disclosure and that he traded shares on that knowledge.

The FBI said Goffer worked at Shottenfeld Group LLC in Manhattan in 2007 and at Galleon Group in the following year before starting his own trading firm.

Police arrested billionaire hedge fund manager Raj Rajaratnam, manager of the Galleon Group, and five others on Oct. 16.

Rajaratnam has denied taking part in a scheme to use inside information to trade stocks at a profit ahead of public announcements.

He has been charged with insider trading in the stock of several companies, including Hilton, Clearwire and Google.