U.S. prosecutors will announce the indictment of nine individuals on Tuesday on charges they were part of an insider trading ring based on cyberhacking of disseminators of news releases, according to a person familiar with the matter.

The case centers on a ring of cyber criminals from Ukraine who hacked into disseminators of news releases and stole press releases about corporate news before it was made public, the source said.

The group then passed the information to a group of traders, who were mostly based in the United States and reaped at least $30 million in illicit profits by trading in hundreds of companies, including Fortune 500 firms, using the non-public information, the source said.